Suits and Atmospheres for Space

Update 1-10-17:  There is one additional limit to consider.  Below about 3 psi pressure of pure oxygen, the absolute humidity is so low,  it causes the lungs to dry out, crack,  and bleed,  if exposure is long-term.  For a pure oxygen suit, the exposure time is actually fairly short,  and the pressures proposed in this article (2.67 to 3.81 psia) are pretty close to the limit anyway,  so they should not present a problem.  The two-gas habitation atmospheres,  where exposure is long-term,  are proposed to be much higher (6.8 to 10.6 psia at 30% oxygen by volume),  thus avoiding the problem completely. 

Update  2-16-16:  Had the wrong plots for Figures 10 & 11;  now corrected.

This article updates and supersedes earlier articles on this subject.  Those are:

Date           title             

1-15-16       Astronaut Facing Drowning Points Out Need for Better Space Suit

11-17-14    Space Suit and Habitat Atmospheres

2-11-14      On-Orbit Repair and Assembly Facility

1-21-11     Fundamental Design Criteria for Alternative Space Suit Approaches

Background

Up to now,  space suits have been designed with 100% oxygen atmospheres inside at suit pressures equaling or even exceeding the partial pressure of oxygen in Earthly air near sea level.  That is probably “overkill”,  which makes the design of more supple space suits difficult,  whether they are conventional “full pressure” suits or the alternative mechanical counterpressure (MCP) suits.  Space station atmospheres have usually been two-gas:  oxygen with nitrogen for dilution,  similar to Earthly air. 

Criteria

There are four things of importance to consider when running numbers for suit and habitation atmosphere design:  (1) the displacement of dry breathing gas pressure by water vapor pressure inside the moist lungs,  reducing the effective partial pressure of oxygen driving diffusion of oxygen across the lung tissues into the blood,  (2) how much or how little oxygen is really needed to stay functional,  (3) reducing the fire danger posed by oxygen enrichment,  and (4) reducing or eliminating the “pre-breathe time” necessary to blow off dissolved nitrogen (or other dilution gases) from the blood when transitioning from a multiple-gas atmosphere to a pure oxygen suit.  These are independent of suit type.

Water Vapor Displacement Effect

The movement of oxygen,  nitrogen,  other dilution gases (if any),  and carbon dioxide across lung membranes is a diffusion process,  driven by the differences of partial pressures,  including those of the dissolved gases in the blood.  Unlike those,  the water vapor in the lungs is dominated by simple evaporation of the liquid phase at body temperature,  attempting to reach the equilibrium value.  This approach to equilibrium (a number straight from the steam tables) is not perfect,  but it’s not a bad estimate either,  and it is easy to compute,  when non-equilibrium is not. 

Having non-equilibrium water vapor pressure reduces the actual water vapor pressure,  and thus reduces dry gas displacement.  This leads to slightly-higher oxygen content inside the wet lung than one would calculate for equilibrium.  Thus equilibrium design is a lower bound on oxygenation:  you actually do slightly better than that in real life.  It’s easy and it’s slightly conservative:  a good tool.

Human body temperature is 98.6 F (37.0 C),  at which the equilibrium vapor pressure of water is 0.061921 atm.  That is the value you subtract from the supplied dry breathing gas pressure to determine the partial pressure of that dry breathing gas inside the wet lungs.  The volume percentage of oxygen in that breathing gas,  applied to the in-lung partial pressure of dry breathing gas,  is then the partial pressure of oxygen in the air inhaled into the wet lungs.  It will be less than the partial pressure of oxygen in the dry breathing gas.  But,  this wet in-lung oxygen is your real design criterion.

How Much or How Little Oxygen is Needed?

This depends upon whom you ask.  The USAF says pilots must use supplemental oxygen when flying in an unpressurized cockpit above 10,000 feet.  The USN is worried more than USAF about loss of night vision,  something well known to be sensitive to hypoxia.  So USN says to use supplemental oxygen above 5000 feet.  The FAA says that pilots flying above 10,000 feet for more than 30 minutes,  and that pilots flying above 14,000 feet for any time at all,  must use supplemental oxygen.  These FAA requirements apply to all civil aircraft,  commercial or private. 

Most of humanity lives within several hundred feet of sea level:  call them “flatlanders” for convenience.  There are lots of people living in cities near 5000 feet elevation.  Flatlanders visiting these elevated places have essentially zero problems acclimatizing almost immediately.  There are also quite a few cities around the world at 10,000 feet.  Flatlanders visiting these elevated places require nothing to a few days to acclimatize,  leading to few if any problems.  Max airliner cabin altitude is also 10,000 feet. 

There are a very few cities in this world located near 15,000 feet above sea level.  The people who live there are well-acclimatized,  but visitors might require significant time to acclimatize,  and will experience some mild problems until they do.  But they eventually do acclimatize,  on a time scale of days to weeks,  usually.  Designing to a 15,000 foot equivalency is certainly feasible,  therefore.  

There are no cities,  but there are a very few rural herders,  and some mountain climbers,  at 20,000 feet who use no supplemental oxygen.  Not very many flatlanders can acclimatize to this,  and it takes months or years to do so for permanent residency.  Yet almost no one dies from this exposure,  especially if it is not prolonged.  So that’s too high for practical design equivalency,  but it is survivable. 

What that suggests is that space suits and habitat atmospheres should be easily feasible and quite acceptable anywhere between sea level and 10,000-to-perhaps-15,000 feet elevation-equivalent oxygenation.  Based on the water vapor displacement discussion above,  the criteria by which to measure this is the wet in-lung oxygen partial pressure,  not the oxygen partial pressure in the dry ambient air at whatever equivalent altitude that we are considering. 

Fire Danger

This is a judgmental factor,  governed by simple human experience.  Most supplemental oxygen systems range from 50% to 100% oxygen,  with well-known fire dangers.  Most hospital oxygen is 60%,  also with well-known fire dangers.  NASA’s rough rule-of-thumb is that nothing over 30% oxygen is safe enough.  For this article,  I will use the 30% max oxygen criterion. 

Pre-Breathe Time

Both oxygen and nitrogen dissolve in the blood.  If you move to another atmosphere at lowered oxygen and nitrogen partial pressures,  what’s in your blood must come out of solution,  a process that requires time.  The bigger the differences in partial pressures driving the solution and un-solution rates,  the faster the process.  Except,  if you try to do this too fast,  the gases form bubbles in your blood before they can diffuse into your exhalation.  This is “the bends”,  which can be quite damaging,  even fatal. 

A person in a space habitation with a multiple-gas atmosphere must generally put on a suit with a pure oxygen atmosphere.  The nitrogen (and any other dilution gases) in his blood must come out of his blood,  but without forming bubbles.  This takes time spent breathing pure oxygen at near-habitation pressures,  before reducing the pressure to the suit design point and going outside.  This time is called the “nitrogen blow-off” or “pre-breathe” time. 

There is a rough rule of thumb derived from deep sea diving experiences,  used by NASA,  that says that if the ratio of nitrogen partial pressure to suit atmosphere pressure is 1.2 or less,  then the required pre-breathe time is zero (decompression may safely be immediate).  Whether this applies separately to all dilution gases,  or collectively to the sum of their partial pressures,  is perhaps still unclear,  but a conservative design approach says apply it to the collective sum.  So that is what I do here. 

What is Required Not to Asphyxiate at High Altitude or in Space

You must have sufficient oxygen pressure in your lungs to oxygenate the blood.  When that oxygen pressure is larger than the local ambient atmospheric pressure at altitude,  a vented oxygen mask cannot work:  you must then breathe oxygen at pressure-above-ambient.  This is called “pressure breathing”,  and it makes you subject to two classes of serious,  even fatal,  problems. 

The immediate effect is from trying to breathe at about 2 psi or more above ambient pressure.  This ruptures the lung tissues,  and is called “pneumothorax”.  It is irreversible and fatal:  you literally drown in your own blood.  This risk is well known among divers;  it is why you never,  ever hold your breath while diving with a breathing rig.  Rising as little as 4 feet while holding your breath can kill you.

One of the longer-term effects is something called “edema”,  which is body parts painfully swelling up with gases and fluids driven out of the blood.  These go into the spaces between cells in the other tissues,  which is what causes the swelling.  For small exposed body parts,  this takes a while:  something like 30 minutes for a hand or foot exposed to vacuum,  when the rest of the body is not.  It can happen quicker with whole-body exposure:  something like 10 minutes. 

The other longer-term effect is simple blood pooling in uncompressed extremities,  like the arms,  and especially the legs,  driven there by the pressure differences.  You faint pretty quickly from this,  something like 10 minutes’ exposure at most,  5-10 seconds at minimum.  It’s quite similar to high gee-exposure in flight:  blood pools in the legs,  leaving your brain starved,  and you faint. 

So you must have pressure-breathing of oxygen,  but your body must also be compressed by the same pressure,  and this has to be fairly-evenly distributed.  This body compression is called “counterpressure”.  Many people were hurt,  disabled,  even killed,  learning these rules.

History of High-Altitude Suits and Space Suits

There are two known ways to achieve the counterpressure:  (1) put yourself inside a gas-tight balloon so that the gas pressure you breathe is also the counterpressure applied to your body,  or (2) use a breathing gas helmet and use very tight garments to mechanically apply the counterpressure all over your body.  The first approach is called a “full pressure suit”,  and the second approach has been implemented as something called a “partial pressure suit”,  or more generically,  a “mechanical counterpressure” suit (MCP suit).  The body simply does not care how the counterpressure is applied. 

The first successful means of pressure-breathing at unsurvivable altitudes was a full pressure suit literally adapted from a deep-sea diver’s hard-hat diving dress,  in the mid 1930’s.  This was literally a rubber balloon with cloth inside to ease friction donning the suit,  and protective canvas on the outside to prevent ruptures to the rubber balloon layer.  Unlike the deep sea application,  this suit is inflated above ambient pressures,  which stiffens the garment immensely.  You’re sealed inside,  so moisture builds up from breath and sweat.  And you are well-insulated and so cannot get rid of body heat.  Movement was extremely restricted in such suits,  and they were extremely uncomfortable,  even debilitating.  A person wearing one could actually do very little in the way of useful activity.

These difficulties were side-stepped with the partial pressure suit of the late 1940’s.  Tubes called capstans were inflated,  drawing the garment very tight about the torso,  arms and legs.  This provided mechanical counterpressure for the breathing oxygen at pressure in the helmet.  That counterpressure was barely adequate and quite uneven.  Hands and feet were left uncompressed.  This was adequate for about 10 minutes maximum,  which was good enough for very high-altitude depressurization accidents and bailouts.  It served well into the 1960’s and beyond,  for those applications.

 Figure 1 – Partial Pressure Suit,  Left;  Early Full Pressure Suit,  Right,  note bellows easing joints

Starting in the late 1950’s,  the advent of high-altitude spy planes and the beginnings of human spaceflight required something better than the partial pressure suit with its short protection interval.  The full pressure suit was updated with better joints that flexed easier,  and by the Apollo program,  water-cooled underwear was added to help keep the astronaut cooler as he worked in the suit.  

The suits and life support backpacks got very large and heavy,  because of these heat and moisture control requirements.  Mobility,  while better,  was still quite restricted.  Particularly difficult is doing anything but rather gross tasks with the clumsy,  bulky pressure gloves.  The higher the suit pressure,  the worse this problem is.  Such suit designs went from 200 pounds of suit and equipment on the moon with Apollo,  to nearly 400 pounds in the shuttle,  and on the space station today.  

 Figure 2 – A Modern Full Pressure Suit as Used on the Space Shuttle (also has maneuvering thrusters)

Suits like this are designed as little “personal spaceships” surrounding the astronaut.  The one garment must protect against any and all conceivable hazards.  Requirements can be contradictory. 

This kind of thing simply will not work very well for astronauts visiting the surfaces of other worlds (moon,  Mars,  etc.).  Movement and joint flexion are still too restricted.  The suits are heavy enough and clumsy enough to limit the ability of an astronaut who has fallen to get back up without help.  If the suit pressure is lowered,  these restrictions ease slightly,  but there are limits to how much change can be made.  But,  this is where we have been since about 1960. 

Except,  for some extremely interesting experiments in MCP,  that were never seriously developed. 

Experiments in MCP

In the mid to late 1960’s,  Dr. Paul Webb,  an expert in high-altitude crew survival,  conducted experiments with an improved MCP suit approach.  He substituted elastic compression garments for the clothing drawn tight by inflated air capstans.  At that time,  the elastic materials used in pantyhose were brand new,  and he used them.  This suit design approach was intended for Apollo on the moon,  but he could not get the design fully developed in time.  It’s been mostly forgotten ever since. 

These materials are not gas-tight;  they are quite porous.  You sweat right through them to cool,  just as with Earthly clothing.  There is no gas pressure in your clothing,  your skin is really actually exposed to vacuum,  but your clothing squeezes you,  thus countering your breathing gas pressure.  That’s all that is really required.  See Figure 3.  The backpack contained liquid makeup oxygen in a Dewar,  plus controls.

No water-cooled underwear is needed,  which eliminates the risk of drowning when your underwear springs a leak (something seen at least twice now with full pressure suits). 

Puncture a full pressure suit,  and you will die if it deflates before you can get inside.  Puncture an elastic leotard (or even the old partial pressure suit),  and there is no leak:  there is no gas in the clothing to leak out.  If the hole is under about 0.1 inch in size,  you may safely ignore it.  Simply sew it up later,  once inside.  If it is bigger,  it still won’t kill you.  You can avoid local vacuum injury to the exposed skin by a simple tight wrap of something like duct tape.  Fix it later when you go inside,  by sewing it up. 

These elastic leotards are easily launderable;  full pressure suits are not.  That is a crucial advantage in dirty,  dusty places like the moon and Mars,  and for repeated long-term use anywhere. 

And Webb changed the design philosophy:  think of this as a pressure-breathing helmet and vacuum-protective underwear,  over which you don whatever protective outerwear fits the task at hand.  

 Figure 3 – Paul Webb’s “Elastic Leotard” MCP Suit of about 1968

Figure 4 – The MCP “Elastic Leotard” Provides Very Excellent Mobility

Dr. Webb’s experiments clearly demonstrated the suppleness and mobility achievable in this MCP elastic approach.  The fact that his test subject was not wearing the insulated coveralls and hiking boots needed for the moon or Mars makes no difference.  Those apparel items are something bought at Walmart or its equivalent.  They do not need to be incorporated into the vacuum-protective underwear.  Nor would they have added any significant impediment to the test subject wearing the elastic leotard. 

The back bend maneuver shown in Figure 4 is completely impossible in today’s full pressure suits.  Yet this test subject in an MCP suit could do the maneuver.  Plus,  the much smaller and lighter backpack evident in Figure 3 would not have compromised this ability. 

Likewise,  the ladder-climbing exercise in Figure 5 would also be virtually impossible in today’s full pressure suits.  It was barely possible in the much-lighter (but still cumbersome) Apollo moonsuit.  And again,  the smaller MCP backpack would not have impeded this activity. 

Early difficulties with breathing while wearing a tight garment were solved by incorporating a tidal-volume breathing bag connected to the helmet,  located on the chest,  and contained within a non-elastic restraint jacket.  The remaining difficulty is only don/doff time,  because of the tightness.

Figure 5 – MCP Suppleness Allows Performance of Tasks Impossible in Full Pressure Suits

In Dr. Webb’s design,  there are elastic compression gloves and booties,  so no body parts are left uncompressed.  If you compare these gloves to the full pressure suit gloves in either Figure 2 or Figure 1 above,  you can see at a glance these are far thinner and far more supple. 

The elastic leotard MCP suit is not a single one-piece garment.  You put it on in many separate pieces and layers.  In particular,  you can don and doff the gloves without disturbing the suit compression on the rest of the body.  There is no risk of losing breathing gas pressure,  as there is none anywhere in the suit,  except the helmet and breathing bag. 

Given the 30 minute interval before swelling starts in a vacuum-exposed hand,  this presents the possibility of doing very fine tasks completely bare-handed in space,  on a short-term basis.  The only other requirement to do this is workpiece temperatures that will not cause thermal injury to the bare hand,  and that has nothing to do with the suit design.   

Webb’s final demonstration test is shown in Figure 6,  where the same test subject is pedaling a bicycle ergonometer in a vacuum chamber for about half an hour.  The simulated altitude was 87,000 feet,  far above the known “vacuum deathpoint” without some kind of pressure suit.  If there were a problem with this design,  it would have shown up in that test.  The subject was breathing via a “hookah” rig as in the mobility tests,  but was wearing the backpack as a check on mobility while working hard.  Suit plus helmet plus backpack was 85 pounds.  Adding hiking boots,  heavy leather or insulated gloves,  and insulated white coveralls might add 5-15 more pounds.  That’s a very supple 90-100-pound spacesuit!!

 Figure 6 – Final Test of “Elastic Leotard” ca. 1968 in Vacuum Chamber at 87,000 feet for Half an Hour

This work by Dr. Webb on the elastic leotard MCP suit was partly funded by NASA,  so they knew by 1968-1970 that this kind of suit would work,  and that it offered some very attractive characteristics.  But NASA has never seriously followed up on this development,  not back then,  nor ever since.  And yet,  this is the kind of suit we really need for long term activities on the surfaces of other worlds,  such as the moon or Mars.  Dr. Webb tried over the years to get private funding without success,  and has now died. 

NASA has in recent years provided grant monies to Dr. Dava Newman at MIT to continue work on a variation of the elastic leotard MCP suit.  This is academic research at relatively small funding levels,  not a major engineering development effort.  Dr. Newman’s variant looks at fewer layers of more-tailored elastic properties,  something not available in Dr. Webb’s day.  Her version is still quite a supple-looking “skinsuit”,  shown in Figure 7. 

Dr. Newman has since been hired to work directly at NASA.  Yet,  there is still no major development effort going on for MCP spacesuits.  Insiders tell me the astronaut office is afraid of MCP because they have been erroneously told that skin exposure to vacuum is fatal.  There’s simply no excuse for that,  given Dr. Webb’s experimental success almost 5 decades ago. 

Running the Numbers on Suit Pressures

I looked at a sea level-equivalent design,  and a design equivalent to 10-15,000 feet,  as bounds on what we might really do for spacesuits.  This applies to either type (full pressure or MCP).  There has to be a little leakage margin for the suit or the breathing system.  You want the leaked-down pressures to still be adequate enough to get back inside without help. 

I based my calculations on wet in-lung partial pressure of oxygen as the criterion,  as discussed above.  I used a spreadsheet to calculate the dry air pressures,  and the displaced in-lung wet pressures for air as a function of altitude on a US 1962 standard day.  Then I looked at pure oxygen at atmospheric pressures as a function of altitude,  and did the wet in-lung displacement on those.  The image of that spreadsheet is given as Figure 8.  At the bottom of the image,  I have converted the design point data into a variety of units of measure for the reader’s convenience. 

For the low-pressure suit design,  I looked at 10 to 14,000 feet air,  highlighted green in the spreadsheet.  There’s a yellow highlight on the 15,000 feet conditions that I used for the leaked-down condition.  I settled on a 12,000 foot design.  It’s pure oxygen counterpart is also highlighted green,  at about 40,500 feet.  The corresponding leakdown is about 42,000 feet.  The wet in-lung oxygen partial pressures for this design are 0.120 atm nominal and 0.107 atm leaked-down,  for a 12% margin. 

For the sea level design,  the corresponding oxygen altitude is 33,000 feet,  with 35,000 feet for its leak-down point.  The corresponding wet in-lung oxygen partial pressures are 0.197 atm nominal and 0.174 atm leaked-down,  for a 13% margin.

 Figure 8 – Spreadsheet Image of Pressures vs Altitude for Suit Designs

Looked at the more usual way,  the “low pressure” suit has a nominal suit pressure of 0.182 atm (2.67 psia),  and can safely leak down to 0.169 atm (2.48 psia).  The “sea level oxygen” suit has a suit pressure of 0.259 atm (3.81 psia),  and can safely leak down to 0.236 atm (3.47 psia).  They are both pure oxygen suits,  requiring dessicant,  carbon dioxide absorbent,  and makeup oxygen.  The margins look different using those numbers,  at 7.7% low-P and 9.7% high-P.  But,  comparing wet in-lung partial pressure of oxygen is the more proper measure,  and the more proper basis for calculating leak-down margins.  So that is the way I did it,  not the usual way. 

Running the Numbers on Habitation Atmospheres

The minimum habitation air pressure obtains when you set its wet in-lung oxygen partial pressure equal to that in the suit.  In other words,  you let the suit drive the habitation atmosphere selection.  You can always set it higher,  but you should not set it lower than suit oxygenation.  Doing this calculation as a function of design suit pressures,  across a range of them,  allows you to see the trends in what is important and what is not.  You also do it for a range of oxygen concentrations (volume percentages) in the habitation,  as the parameter on a parametric plot with multiple curves. 

There are two questions to investigate:  what effects (if any) suit pressure selection might have upon habitat pressure,  and also upon the pre-breathe time requirements.    Again,  I did this in a spreadsheet,  images from which are given in Figure 9.     

The illustrated sequence of calculations is simple and straightforward.  Start with the suit pressure,  which is pure dry oxygen.  Do the water vapor displacement subtraction to determine the suit wet in-lung oxygen partial pressure.  Make that value the habitation wet in-lung partial pressure of oxygen.  Use the volume percentage oxygen to figure the wet in-lung partial pressure of nitrogen,  then sum the gases to obtain the wet in-lung partial pressure of dry air.  Then add back in the partial pressure of water vapor to determine the habitation atmosphere total pressure before any vapor displacement occurs.  

 Figure 9 – Spreadsheet Images for Habitation Atmospheres Driven to Match Suit Design Pressure

I did this for the normal Earthly air oxygen percentage of 20.94%,  for the max allowable percentage acceptable from a fire risk standpoint (30%),  and finally an even higher oxygen percentage that meets the “no pre-breathe time” rule of thumb.  That last value is just about 41%.  This data can also be plotted in the same basic format to visualize the true nature of the pre-breathe trends. 

I plotted habitation atmosphere pressures versus suit pressures in Figure 10,  parametric on oxygen percentages.  For the highest suit pressure and lowest oxygen percentage,  the minimum required atmosphere pressure can be right at sea level standard pressure,  the rest are reduced-pressure. 

I plotted the ratio of habitation nitrogen partial pressure to suit pressure (the pre-breathe factor) versus suit pressure in Figure 11,  again parametric on oxygen percentages.  Those are relatively less sensitive to suit pressure,  but more sensitive to habitation oxygen percentage:  richer oxygen is closer to feasibility for no pre-breathe time,  and the stronger effect of the two. 

You can eliminate pre-breathe time (at any feasible suit pressure) by using just about 41% oxygen,  unacceptable from a fire hazard standpoint.  Otherwise,  use the greatest oxygen percentage (30%) that you safely can,  and also use the lowest credible suit pressure (a weaker effect,  but still significant) to achieve the minimum required pre-breathe time. 

Figure 10 – Effects of Suit Design Pressure on Habitation Pressure

 Figure 11 – Effects of Suit Design Pressure on Pre-Breathe Time Requirements

Figured at the nominal suit pressures for the “sea level oxygen” and low pressure designs discussed above,  the corresponding habitat atmospheres are described (and converted to a variety of units of measure) in the data of Figure 12.  Again,  this is a spreadsheet image.  

Figure 12 – Results for Preferred Suit Designs and Oxygen Percentages

I do not have a way to calculate the actual pre-breathe time requirement from the pre-breathe factor,  something needed when that factor exceeds about 1.2.  But,  the larger the factor,  the longer the time,  that much is certain.  So there really is some benefit in terms of pre-breathe time to using the lowest credible suit pressures. 

Checking the Upper Limit

There is one final thing to check during pre-breathe activities:  upper limits on the pressure of the pure oxygen.  With no more than 1 atm of habitation pressure,  this is not a problem.  The upper limit for pure oxygen exposure is known to be 1 atm from deep-sea diving.  Pure oxygen exposure becomes fatal at 2 atm,  although this does take several minutes to occur.  The usual first symptom is convulsions. 

Conclusions

#1. Habitations should probably use a two-gas atmosphere that is oxygen-enriched (to the fire safety limit),  basically an oxygen-enriched synthetic air:  30% by volume oxygen and 70% nitrogen.  That is a simple and easy thing to do. 

#2.  The minimum habitation atmospheric pressure depends upon the selected suit design pressure,  ranging from near 0.462 atm (6.8 psia) for the low-pressure designs,  to 0.720 atm (10.6 psia) for the higher-pressure designs,  all when using the 30% oxygen composition.

#3. The range of credible suit pressures extends from 0.182 atm (2.67 psia) to 0.259 atm (3.81 psia). 

#4. Using the lower suit pressure design decreases required pre-breathe time,  but not to zero. 

#5. The suit pressure designs and habitation atmospheres recommended here apply to either full-pressure suits or MCP suits. 

#6.  Far better mobility in a much lighter and more versatile suit design can be achieved using MCP;  so these suits need to developed into a routinely-reliable form as soon as possible! 

#7.  Raising the habitation pressure above minimum increases pre-breathe time required somewhat.  

Wimpy Gets His (no comment needed)

Astronaut Facing Drowning Points Out Need for Better Space Suit

Note updates 1-29-16 in red below.

Astronauts Tim Peake and Tim Kopra were forced to cut short an EVA due to water leaking into Kopra’s helmet.  This is the very same suit worn by astronaut Parmitano in 2013,  who nearly drowned from a water leak into the helmet.  That suit was extensively refurbished after the 2013 incident,  but clearly there is still a risk associated with its water cooling system.

So,  do all spacesuits need water cooling systems?  No.  The fundamental job is providing a way for you to breathe,  and surprisingly enough,  that does not necessarily mean protecting you from exposure to vacuum.

As long as your heart is beating and your blood pressure hasn’t zeroed,  exposure to vacuum is not fatal and your blood does not boil.  Nothing “explodes” either.  Nor do you instantly freeze or fry,  something that takes longer than anoxia death in vacuum.  The various science fiction shows have lied to you. 

You will start to die within about 2 minutes or so of whole-body exposure to vacuum,  because of nothing more than anoxia,  since oxygen at zero pressure will not diffuse across your lung membranes into your blood. 

In point of fact,  the reverse diffusion of oxygen from your blood to the environment in vacuum is quite enhanced over what we normally experience down here on the surface of the Earth.  So anoxia sets-in quicker upon exposure to vacuum “out there”,  than it does by gross strangulation down here (usually about 4 minutes,  but it can take twice that long,  depending upon your initial blood oxygen levels). 

In experiments and accidents,  people and animals have survived whole-body exposure to vacuum for up to about 2 minutes.  And that’s a fact,  Jack!  This has been known since the 1960’s. 

What’s minimally required to survive in space is an oxygen supply at sufficient pressure to cause adequate diffusion of oxygen across the lung membranes into the blood.  Nothing more than that.  For most folks,  this is in the neighborhood of 2-3 psi pressure of pure oxygen,  or 2-3 psi “partial pressure” of oxygen in a more complicated atmosphere. 

Sea level air has just about 3 psi partial pressure of oxygen,  while air at 10,000 feet elevations has about 2.1 psi.  Some folks are adapted to 15,000,  even 20,000 foot elevations.   That last is about 1.4 psi partial pressure of oxygen.  That’s about the utter minimum for survivable breathing gas pressure,  even if pure oxygen.  But it is based on actual people living active lives at such conditions.

The most immediate idea that comes to mind is just to breathe oxygen at 2 to 3 psi pressure,  with a mask sealed tightly to your face.  This is called "pressure breathing".  
  

There is an immediate danger with "pressure breathing":  if oxygen pressure in the lungs exceeds about 2 psi without counterbalancing pressure within the body,  the lung tissues rupture in an event called "pneumo-thorax".  This is fatal and irreversible and immediate,  you drown in your own blood.  It is a well known risk among scuba divers.

There is a another complication that requires time:  counter-pressure must be exerted upon the body that is more-or-less equal to the breathing gas pressure,  or else those breathing gases will diffuse out of the blood into the spaces between cells in the body,  causing swelling,  disability,  even death.  We have known that since the late 1940’s.

It takes about 30 minutes for significant swelling to happen to a vacuum-exposed small body part like a hand or foot.  It happens much quicker (5-10 minutes) if the whole body is uncompressed while breathing oxygen at pressure.  We learned these figures by hard experience,  since the late 1940’s.  They are accurate. 

There is also a mitigating factor:  the body “does not care one whit” how this counterbalancing pressure is applied!  It can be the pressure of the gas within the current modern space pressure suit,  or it can be a mechanical “squeeze” exerted by other means,  as long as it is applied whole-body.  Pressure is pressure,  no matter how it is applied! 

Our cells are essentially little water balloons:  the pressure in them,  and between them,  goes up whether we put them inside a container at some gas pressure,  or if we simply grab them and physically squeeze them (like a water balloon) in our hands.  Doesn’t matter,  as long as it gets done.

Modern space suits are what we call “full pressure suits”,  which means they are literally gas-tight balloons whose internal gas pressure is the compression the body needs to counterbalance the breathing gas pressure.  These suits isolate you chemically and thermally from your environment;  one layer is quite literally a gas-impermeable rubber balloon.  

It is difficult at best to expel from such a suit the heat your body produces,  especially if you are active.  Your breath and your sweat fill your suit (and your helmet) with moisture,  thus fogging your visor.  There is also carbon dioxide to absorb.  We have fully understood this since the 1950’s at the very latest.  Our first efforts date to the 1930’s. 

The heat problem requires water-cooled underwear to carry your body heat to your backpack,  where some sort of “air conditioner” equipment expels that heat to space.  Likewise,  your breathing gas requires considerable regeneratable dessicant to get rid of the moisture load from your breath,  and more especially,  your body sweat (the larger of the two sources).    The carbon dioxide absorbent also needs to be regeneratable. 

Your makeup oxygen supply is not lightweight,  all by itself,  although makeup from a flask of liquid oxygen is the most efficient.  The combination of all this plus adequate insulation against hot and cold makes your suit,  and your life support backpack,  quite heavy.  It’s been like that since the 200+ pound Apollo moonsuit,  all through the space shuttle program (300+ pounds),  and is still like that on the international space station (ISS) today (close to 400 pounds). 

But,  what if you relied on mechanical-physical compression by a tight garment instead?  This was exactly how the early “partial pressure” suits worked,  and they worked quite well,  actually,  for 10-minute bailouts,  beginning in the late 1940’s.  Hands and feet were uncompressed,  and compression over the limbs and body was rather uneven,  but it worked for 10 minutes anyway. 

Such a compression garment need not hold gas pressure at all,  it can be entirely porous!  You can sweat right through it into vacuum,  which is actually more efficient cooling than here on Earth,  because of inherent moisture vaporization into vacuum.  So you need no mechanical cooling system at all,  and your moisture load is only breath,  not breath-plus-sweat.  Your life support backpack reduces to just the makeup oxygen,  plus minimal dessicant,  and the same carbon dioxide absorbent. 

You still need protection against hot and cold,  but this can be an over-garment.  It simply need not be part of your compression garment!  Think vacuum-protective underwear,  overlain by whatever insulation,  at whatever level you need,  for the job at hand. 

That gives you the freedom to dress in layers,  just like down here on Earth!  In point of fact,  you can use ordinary Earth garments for this insulation function.  Coveralls,  aprons,  coats,  pants,  shoes,  and gloves,  all exactly the same as we wear down here. 

Believe it or not,  this notion of vacuum-protective underwear (known as “mechanical counter-pressure” or “MCP”) was tested and somewhat-developed in the late 1960’s,  quite successfully,  by Dr. Paul Webb.  The compression garment,  breathing helmet,  and oxygen backpack that he tested totaled 85 pounds. In its final form,  the difficulty of breathing while wearing a very tight garment was eased by incorporating a breathing tidal-volume bag on the chest within a non-elastic restraining jacket,  instead of garment compression.

Add 5-15 lb of insulating garments,  gloves,  and boots,  and you are talking about a spacesuit that weighs around 100 pounds,  not the 300-400 pounds currently in use!  Plus,  it is a whole lot more dexterous:  you can bend sharply over,  climb ladders,  and crawl into small spaces,  something not at all possible with a “normal” modern spacesuit. If you fall over in a 400 pound full pressure suit,  it is likely you cannot get up on your feet again very effectively.  If there is no one close by,  you may lay there till you die.  That doesn't happen in a supple,  100-pound MCP suit.

This stuff worked long ago:  I have seen the 1968-vintage video of Dr. Webb’s test subject in a vacuum tank,  pedaling a bicycle ergonometer for half an hour,  and wearing nothing but 6-7 layers of tight pantyhose material and a breathing helmet.  The simulated altitude was 87,000 feet,  where even a pure oxygen atmosphere would still only be 0.293 psia.  If there were a problem with this approach,  it would have shown up in that half an hour:  no problems showed up! 

This test effort was partially-funded by NASA:  they have known that this alternative works for almost half a century.  Irrational attitudes and monied interests,  not actual facts,  prevent its application today.  Small amounts of grant money to Dr. Dava Newman at MIT have supported some work on this “MCP” suit concept,  but nothing at any of NASA’s favored spacesuit contractors.  Dr. Newman has since been hired by NASA,  but there is still no development effort for an MCP suit.  

Here's one more advantage of MCP over a standard full pressure suit.  If you puncture a full pressure suit,  and you cannot get inside before it deflates,  you are dead.  If you puncture an MCP suit,  nothing happens,  because the garment does not contain any gas under pressure at all.  If the hole is smaller than about 0.1 inch in size,  you may ignore it completely,  and just sew it up later.  If it's a bigger tear,  a tight wrap of duct tape will protect the exposed skin from localized vacuum damage until you can go inside and make repairs.  

This MCP suit is the dexterous,  easily-launderable spacesuit we have always dreamed of!  There is simply no excuse not to do this!  So what if it takes some time and effort to don such tight layers?  Further,  if you figure out some scheme to relax and apply the fabric tension “at will”,  even that objection goes away. 

And,  with MCP,  there is zero risk of drowning an astronaut,  because there is no water-cooled underwear!  Astronaut Kopra on the ISS is just the latest to face this lethal risk.  

Related articles on this site:

Date           title

2-15-16    Suits and Atmospheres for Space (the latest!!)

1-15-16   Astronaut Facing Drowning Points Out Need for Better Suit

11-17-14    Space Suit and Habitat Atmospheres

2-11-14      On-Orbit Repair and Assembly Facility

                  

1-21-11     Fundamental Design Criteria for Alternative Space Suit Approaches

Edits/updates:

1-16-16 two new lead-in paragraphs,  plus rewording of final paragraph,  plus new paragraph 9 about pneumo-thorax.

1-29-16  added information in multiple locations,  red text.

Facts Must Trump Politics

Update 8-4-16:

There are some related articles elsewhere on this site,  one of which seems to be modestly popular with readers (the 7-29-16 article).  Another one is just a funny (the 4-24-16 article).  All share the search keyword “idiocy in politics”.  Here’s the list:

8-4-16….Evaluation of Choices for 2016

7-29-16…..Stuff You Normally Do Not Think About

6-5-16…….Trump?  NO!!

4-24-16….Better Choices in November

12-21-15..Facts Must Trump Politics  (this one)

Update 7-27-16:  Today Trump publicly appealed to (state-supported) Russian hackers to uncover the missing Clinton state department emails.  Considering the bad state of affairs between the US and Russia,  due largely to Putin's ambitions for a new Russian empire,  this is borderline treason on Trump's part.  

"Aid and comfort to the enemy" with 6+ witnesses,  per the definition.  Putin wants Trump to win and hates Clinton.  He is trying to sway our election for his own purposes by releasing hacked Clinton files.  I really do not like that.  And I really hate the prospect of a president the Russians can influence so easily to their own ends.  

Update 6-12-16:  It's Clinton vs Trump for sure.  I absolutely do not want loose-cannon Trump!  

The real question now is whether Clinton can overcome her trust issues well enough to pull in Sanders voters and beat Trump,  come November.  And,  there is the Elizabeth Warren factor.  I submit that both Warren and Sanders be made part of Clinton's proposed government for the Nov '16 ticket.  

I would recommend that Sanders be Clinton's VP,  and Warren be made some high cabinet post.  That would re-energize all the Sanders voters,  so that they would turn out and help greatly to defeat Trump.  Plus,  having Sanders in the White House as VP would put the brakes on Clinton's "shyster lawyer" attitude problem,  that causes all the negative trust issues she brings.  Plus,  having Warren in the cabinet helps pull in more yet of the newly-rising "left" in the Democratic party.  It's not about being totally-centrist anymore.  

I think it more important that Sanders be VP and Warren a Cabinet member,  than the other way around.  I think this would re-unify the Democrats better,  and contribute far more toward defeating Trump in November.  The shirt-tail effect says that Democrats could regain control of the Senate and perhaps the House,  in November,  if this is a convincing-enough win of the White House.  

As for "shyster lawyer" attitude problems with Clinton,  these summarize succinctly as (1) "rules are for other people",  and (2) "I'm only sorry I got caught".  She really needs somebody to offset these liabilities.  Sanders could do that better than Warren.

The matter of fact or fiction should be an objective decision.  Politics (or any other predilection) has nothing to do with whether something is factual or not.  This is something far too often ignored by politicians and appointed officials.   It is ignored by too many voters,  as well. 

Finger on the Nuclear Button

Anybody with their finger on the nuclear trigger button needs to base their decisions on real,  verifiable facts.  If they have a predilection for fictions instead of fact,  they are not qualified to hold that position.  Too much is stake to allow “convenient lies”,  or election-campaign “sound bites”,  or party agenda to substitute for rational and informed thought. 

Immigration

Anybody with decision-making authority about immigration needs to base their decisions on real,  verifiable facts.   It is simply too easy to discriminate arbitrarily if these decisions are made based on political fictions.   This evil usually takes the form of a scapegoat group to be blamed for all ills,  which is really how you recognize when you are being lied to.   The last notable example was Adolf Hitler,  who blamed Jews for everything wrong in Germany after World War 1.  And then he tried to kill them all.   And we all know how well that episode turned out. 

Safety Net Programs

Anybody making decisions about the social safety nets we choose to employ (such as Social Security and Medicare) needs to make those decisions upon verifiable facts.  To do otherwise is egregious discrimination against those who happen not to be so very wealthy.   Such discrimination is wrong,  no matter what form it takes.

Regulations on the Economy

Anyone making decisions about the regulations upon our economy needs to base their decisions upon verifiable fact,  including the historically-demonstrated fact that completely-unregulated capitalism has always degenerated into piracy and economic slavery.  It’s simply not a fair market if there are no rules to ensure fair play. 

Regulated to avoid these abuses,  capitalism then takes its rightful place as the most powerful engine of creation ever devised by man.  These are the “two-sides-of-the-same-coin” facts that should never be “trumped” by political ideologies.  From any party,  or any sub-group.

Climate Change

Anybody making decisions about what to do in response to climate change needs to base their decisions upon verifiable facts,  including the demonstrated reality of climate change,  regardless of who or what might be causing it.  Much more than just this year’s bottom lines for some giant corporations is involved with this issue. 

In General

Similar considerations apply to any issue one cares to raise.   Facts are key,  and what is fact is not a political decision. 

My message is this:  pay attention to fact-checking when political campaigns go on.  You will have to take off your political blinders and propaganda lenses to do this effectively.  Ditch the political belief systems.  Do not believe the propaganda.  Look only at what actually “is”.  Candidates who play fast and loose with facts are simply not qualified to make decisions about your lives.   Do not vote for them.

So few elected (or appointed) officials qualify today as people who deal in real facts.  That is why I have generally not voted “for” anyone in decades.  I generally vote instead only for the lesser of the evils available,  and evil they usually are,  because of the money that buys elections.  The common man cannot afford to run for office in our USA.  That has been true for about 200 years now,  and it desperately needs to be changed. 

If in doubt,  I vote “no” or “against”.  That policy has served me well.  

Update:  Specifics for Election Year 2016

Donald J. Trump – NO!!!!  Here’s why:  complete denial of facts on every issue listed above,  which means he is completely unqualified to be making decisions affecting the entire country.  His shifting and extreme positions are designed to create buzz,  not solutions.  Putin likes the idea of President Trump,  because it would be easy to push a publicity-hound clown around,  and with him,  the entire country.   Trump is unstable and extremist enough that I absolutely do not want his finger on the nuclear button!

Update 2-25-16:  nothing but a power-hungry demagogue who tells lies about others,  provides a group to blame for our troubles,  provides platitudes-not-plans when he speaks;  as a result,  he reminds me of no one so much as Adolf Hitler running for office in early 1930's Germany.   We do NOT meed to repeat that history!  

Update 3-16-16:  the violence of Trump supporters suppressing opposition at his rallies is chillingly reminiscent of Hitler and his SA "brown shirts" at rallies in Germany in the late 1920's and early 1930's,  and also of Mussolini's fascisti "black shirts" in the 1920's.  

Ted Cruz – NO!!!!  Here’s why:  the not-Trump choice for the GOP is really just a Trump “mini-me”.  He has exactly the same problems with denial of facts and with extremist nonsense to create buzz,  not solutions.  Therefore,  he is similarly not qualified to be making decisions for the entire country.  He’s a tea party favorite (infamous for their “my way or the highway” approach to things that prevents effective governance),  and would govern for party advantage at the expense of the people (a real evil bordering upon treason during wartime).   He has already demonstrated this by orchestrating the government shutdown.  He is far too extremist to have his finger on the nuclear button. 

Update 2-25-16:  nothing but a power-hungry demagogue who tells lies about others,  provides a group to blame for our troubles,  provides platitudes-not-plans when he speaks;  otherwise identical to Trump in every other way,  which is why I call him a Trump "mini-me".  The same comparison to 1930-vintage Hitler applies.  Just as with Trump,  we do NOT need to repeat that history!

Marco Rubio – He might be acceptable as long he does not have a party majority in both houses of Congress to support him.  His approaches to many issues seem reasoned and reasonable.  But he’s awfully young:  I’d like to see him serve another term in the Senate before attempting the Presidency.   That is the problem we already just had with Obama (who also should have gained more experience in the Senate before becoming President).   I don’t know enough about him to trust that he will govern for the benefit of all,  and not just govern for party advantage at the expense of the people,  which is why I don’t want his party in control of both houses if he were President. 

Update 3-16-16:  it would appear that other folks noticed the same young/inexperienced factor that I called out in the preceding paragraph.  He did not win his home state,  and pulled out.  

Jeb Bush – Seems to be similar in many ways to Rubio,  plus he has real experience at governing that Rubio does not have.  I know enough about him to think that he would try to govern for the benefit of all,  and not just for party advantage,  but only so long as he surrounds himself with a diversity of advisors.  His brother (Bush 43) already made that mistake:  surrounded by nothing but neocons who wanted to wage war for oil,  that’s what “W” did.  Jeb is not “W”,  but the same risk is still there.  So I’d rather not see him supported by a party majority in both houses of Congress,  should he be elected.  Update 2-25-16:  now out of the running unless drafted at the convention.  

Chris Christie – This one may be the best the Republicans have to offer,  by far.  He has experience governing,  he has the backbone to be forceful in foreign affairs,  and he has the wisdom to set aside party considerations and govern for the benefit of all (demonstrated during Hurricane Sandy).  I suspect he would make an acceptable president regardless of who controls Congress.   He might even be a good one.  I do hope the Republicans avoid the Trump vs “not-Trump” Cruz choice at their convention,  by drafting Christie.  Update 2-25-16:  now out of the running unless drafted at the convention.  Update 2-29-16:  has backed Trump,  which I find disappointing (but not at all surprising,  after how his own party has treated him,  following the Hurricane Sandy ordeal).  

Update 3-16-16:  The only remaining non-extremist candidate among the Republicans is Kasich of Ohio.  I hope his win in Ohio forces the GOP to a brokered convention fight and results in an acceptable candidate in November.  Otherwise,  it doesn't matter who the Democrats run,  whoever it is gets my vote to avoid a Hitleresque extremist takeover of the White House.  We are in danger!

Hillary Clinton – She certainly has the experience in governance,  and she certainly has the backbone to deal with foreign affairs.  But she is demonstrably afflicted with a bad case of “shyster-lawyer” attitude:  (1) a predilection for lying,  and (2) a disregard for the rules.  This shows up as low rating for trust in the polls.  She was the brains and ambition behind Bill,  but does not have Bill’s grasp of doing right by the people (a sort of “noblesse oblige”).  I think she would not go off “half-cocked” on the nuclear button.  She might be acceptable as President,  but the shyster-lawyer effect will cause her to have scandal after scandal,  just as it always has since Bill was President.  So there are very definite and serious pluses and minuses with her. 

Bernie Sanders – I don’t yet know a lot about him.  He seems quite personable and reasonable,  just to hear him talk.  A self-described “democratic socialist”,  I’m not at all sure he is as far-left as he seems to many.  He’s probably only “left-center” for the New England region he comes from.  He does have experience in government,  and is demonstrably independent-of-party enough to trust that he would try to govern for the benefit of all of us.  Might actually be an acceptable President.  I think he would be trustable with the nuclear button. 

Update 2-25-16:  the more I hear him speak,  the better he sounds. I just wish he had not tarred himself with the self-description "socialist democrat".  Nowhere near as crazy as Trump or Cruz.  Does not carry all the scandal baggage that Hillary Clinton brings.  

Republican Agenda – as a broad-brush generalization:  tax breaks that almost exclusively favor the rich,  justified by “trickle-down economics” (something tried since Reagan and it has never,  ever worked).  These tax breaks are a reward for campaign contributions from those same rich entities.  The Republicans talk a lot about reducing the size and expense of government,  but never actually do it.  They do tend to be stronger and more forceful as regards foreign affairs,  although this sometimes gets us into deep trouble (example:  recent neocon wars for oil in the middle east under Bush 43). 

Problem:  the Republican party is tearing itself apart without actually splitting.  The extremist right wing coalition (of tea party political extremists and extremist Christians) has the party hog-tied into a turn to the extreme right,  without actually being a majority within the party.  If the split were actually to happen,  neither group would have the following to be a factor in national politics,  which is precisely why they have not yet split.  Eventually,  they will,  or else the Republicans will eventually fade from national significance.  Most Americans have a distaste for extremism. 

Most of their social agenda (top issues:  overturning abortion and Obamacare) I vehemently disagree with:  I think Roe vs Wade better represents the majority of Americans,  and I have seen no concrete proposals to replace Obamacare.  They do support Second Amendment gun rights,  which I agree with. 

Update 2-25-16:  I can certainly see the influence that the tea party/ extremist fundamentalist Christian base is having:  all the GOP candidates running locally here in central Texas are going out of their way to out-Trump Trump.  All I see in their ad campaigns is "blame the illegal immigrants for everything" nonsense,  coupled with defund Planned Parenthood and repeal Roe vs Wade nonsense.  Sounds almost exactly like 1932 Germany.  

Democrat Agenda – I pretty much agree with their social agenda,  excepting increased gun control,  which I utterly abhor.  The party tends to adopt measures immediately,  with the promise to figure out how to fund it later,  which they never do (neither do the Republicans).  They do tend to believe in a larger,  more-activist government,  and the more left-leaning members are more willing to experiment with social engineering,  something I don’t think wise.  (Actually,  the far-right Republicans also want to experiment with social engineering,  just different in the details,  but just as unwise.) 

Update 2-25-16:  the Democrats are very definitely the lesser of two evils,  pretty much at all levels from local to national.  I hate to say that,  but I will NOT vote for a bunch of Hitler clones.  

My own take on this is mixed:  there are things that only government can do,  and there are things that are better-supplied by our free market business communities.  Wisdom lies in knowing which is which,  a decision that should be objective and not political.  Government exists to provide those necessary things that business either cannot or will not supply.  Both parties have very serious failings regarding this.  The Democrats create more government offices and programs,  but (just like the Republicans) never act to eliminate them,  once they are no longer useful. 

The Democrats are stereotyped as “soft” on foreign affairs,  although FDR,  Harry Truman,  JFK,  LBJ,  and Barack Obama are all “exceptions”,  in my opinion.   (I include Obama because he has killed more people with drone attacks than George W. Bush ever even thought about.)  I really think this is more determined by individual personalities than it is by any sort of party agenda. 

I don’t like the way the Democrats (under LBJ) took the social security trust fund and made it part of the federal government general fund.  This is in large part why the social security program is now perceived as going broke.  This was done for political expedience,  and is only one example (among many) of why I think prioritizing party advantage above the good of all the people is tantamount to treason.

My hopes –

I am not classifiable as either Republican or Democrat.  I am a “dyed-in-the-wool” independent.  I am an American,  first and foremost.  You might as well know that,  if you have not yet guessed. 

I hope the Democrats draft Joe Biden at their convention as the “not-Hillary” candidate who could actually win the election.  He is a decent,  thoughtful man,  with lots of direct relevant experience in government.  He could be a good President,  perhaps even a great one,  occasional “foot-in-mouth disease” notwithstanding.  He can be trusted with the nuclear button.  I think he can be trusted to prioritize serving all the people above party advantage.  Update 3-3-16:  if they drafted Sanders,  I'd be OK with that.  

I hope the Republicans draft Chris Christie at their convention as the (1) not-Trump,  and (2) not Trump‘s “mini-me” (meaning Cruz) candidate.  Christie could actually win the election.  As described above,  I think he could be a good President.  Essentially,  these are the same reasons that underlie my opinion of Biden.  Update 3-3-16:  unfortunately,  he has become a symbol of scorn as "Trump's hostage".  I was disappointed in him for endorsing Trump.  His political credibility has pretty much now zeroed because of that.  

I don’t know anything about any of the other candidates not named above.  Accordingly,  my rule-of-thumb would be vote “against”.  I’m sorry if that offends,  but my policy of voting “no” or “against” when I don’t know,  has served me well for a very long time now. 

Best-case scenario:  the election is Biden versus Christie.  Either could serve well,  regardless of who controls the houses of Congress.  I would hope that both men have the wisdom to include the other man as a major figure in his government,  whichever man wins.  Nothing could be more healing of the division among Americans,  both symbolically,  and in a very real-and-practical sense. 

Worst-case scenario:  the election is Trump versus Hillary.  I’d have to vote for Hillary as the lesser of two considerable evils.  I think I can trust her finger on the nuclear button.  Trump,  I do not trust at all,  with the nuclear button. 

Probable Scenario:  Trump (high) or Cruz (low) versus Hillary Clinton.  Frankly,  I'd vote against either Trump or Cruz no matter who the Democrats run!  We simply cannot afford to have the White House taken over by an extremist,  with his finger on the nuclear button.  I hope that Clinton has the wisdom to include Sanders in her proposed government.  Especially if he was her running mate,  I think the Dems would stomp a GOP-extremist in November,  thus saving us from a clone of the Third Reich right here in America.  

Update 2-9-16:  I see no reason to change any of these evaluations.  

Update 2-25-16:  see dated red text inserted above,  in multiple locations.  

Update 2-29-16:  see dated blue text inserted above,  in one location.

Update 3-3-16:  see purple text inserted two places above.  

Update 3-16-16:  see orange text inserted four places above.

Update 6-8-16:  It will be Clinton vs Trump.  Trump is simply unacceptable,  to almost anyone of  remotely-decent common sense,  including an awful lot of Republicans.  Clinton,  in spite of her historic low approval ratings,  is definitely the lesser of two evils.  

The Democrats could ensure that they win by a landslide in November,  if they run Sanders as Clinton's VP candidate.  He would tend to keep her more honest if he were a major part of her government.  A lot of people have a "gut feel" that would agree.  And he would be there to represent the wishes of those who supported him.  

It's a winning ticket (Clinton + Sanders vs Trump + whoever).  I hope the Democrats are wise enough to recognize that during their convention (Update 8-13-16 -- they were not,  but they were wise enough to include a lot of Sanders' issues as their platform).  

"White Trash Christmas" 2015

This is the Christmas 2015 version of what has become our traditional Christmas yard display at the Johnson household.  We call it "White Trash Christmas".

The tree is something I built for the City of McGregor some years ago,  something I call the "Iron Christmas Tree".   The city doesn't use it anymore,  so we do.  It erects easily,  but knocks down to store in a very small space.  I made it out of rebar and all-thread rod,  plus some odds and ends for fittings.

The Santa-and-reindeer paraody is a cheap plastic Santa with a light inside,  using a wheelbarrow as his sleigh,  and a garbage bag in an old steel trash can as his bag of toys.  The reindeer team is a set of plastic lawn flamingoes with pipe-cleaner "antlers",  all lit up internally,  and all "hitched" to the "sleigh" with yellow caution tape.

You'll notice there are 10 flamingoes,  not eight.  The lone leader is "Rudolph",  followed by four pairs for eight,  all named as in the poem,  and a lone follower named "Bambi".  I haven't figured out yet how to give "Rudolph" a glowing red nose (beak).

This display has been our yard decoration since about 1997 or 1998.  It has taken multiple forms over the years,  but this seems to be the funniest.  I hope you like it as well as we do.

Bounding Analysis: Single Stage to Orbit Spaceplane, Vertical Launch

The question at hand is:  how feasible is a single-stage spaceplane to orbit and back,  that has airliner-like characteristics in order to lower ticket costs for passengers,  or per-pound costs for cargo (or any other effectiveness criterion, including the difficulty and cost of military missions).  The notion behind this question is that until spaceships can be operated like airplanes,  costs of access to orbit will simply be too high to do anything but the most critical tasks there,  the ones for which cost is ignored. 

To answer the question at hand I did a little approximate bounding calculation.  I used the weight statement of a well-proven,  long-serving airliner as the weight statement for my spaceplane.  I assumed a vertical launch,  non-lifting ballistic fast ascent to minimize gravity and drag losses at about 10% of the orbital speed to be achieved.  (If you stay low at very high speed,  the drag losses can easily exceed 100%-300% of orbit speed.)  I also assumed on-orbit,  de-orbit,  and go-around-at-landing propulsion weights to be part of the inert weights on ascent (!!!!). 

Some may argue with my using the high inert weight fraction of the airliner for the spaceplane.  But I would remind them that if you want true airliner characteristics,  then the vehicle must be able serve for about half a century and about 40,000 landing/take-off cycles,  without a single major airframe rebuild.  That’s what airliners do,  and their airframes not subjected to the abusive loads that a spacecraft must endure.  We are talking about an aluminum airframe whose entire exterior must be protected by some sort of reusable heat shield (which must serve just as long without a rebuild).  The 5-10% inert fractions of rocket stages are just entirely inappropriate assumptions to make for a winged spaceplane. 

The analysis uses the rocket equation with a corrected delta-vee requirement.  I used 25,000 ft/sec as the velocity to be achieved (maybe 26,000 is better,  but so what?).  This is for a low Earth orbit eastward at no more than about 23 degrees inclination.  Orbital altitude might be around 100-300 statute miles. 

I used customary US units for this;  metric conversions for mass in lbm (usually the meaning of weights in lb) are 2.205 lbm = 1.0 kg.  Conversions for thrust:  1.0 lb = 4.45 Newtons.  Weight (mass) ratios and Isp,  sec need no conversion.  For lengths,  1.0 meter = 3.2808333 feet.  I did approximate the rocket exhaust velocity as Isp x standard acceleration of gravity.  1 statute mile = 1.609 km. 

The situation and aircraft data that I used are given in Figure 1.  The spaceplane specific impulse (Isp) requirements shown there are to be interpreted as an average for the entire ascent trajectory.  Note that the max cargo weight and max fuel capacity of the Boeing 747-100 airplane cannot both be had,  simultaneously.  The gross weight limitation restricts the sum of these to a fixed amount shown in the figure. 

I went ahead and used these limitations to figure my spaceplane at max payload and at max fuel load.  I solved the rocket equation for a given mass ratio and theoretical delta-vee,  for the exhaust velocity required to accomplish the mission,  and then converted that to a trajectory-averaged specific impulse (Isp) requirement.  At modest acceleration,  you leave the air at about Mach 2 / 130,000 feet conditions,  still near vertical.    The depression to horizontal and acceleration to high speed occurs exoatmospheric. 

There is a thrust greater than weight requirement for vertical takeoff that combines with a diameter limit,  into a frontal thrust density that must be equaled or exceeded in order to lift off.  Later in the trajectory,  because the ascent is still near-vertical,  thrust minus drag and that same diameter combine so that the same frontal net force density must still be exceeded in order to continue climbing.  Those estimates are also given in the figure.  

 Figure 1 – The Data Used for the Bounding Analysis

I did not even try to estimate drag data.  But,  on a frontal cross section area basis (not wing planform area !!!!),  it would be very hard indeed to imagine any shape with a drag coefficient averaging less than 0.4 across the speed range from launch to atmospheric exit at around Mach 2-ish.  Drag is a very significant force,  especially around Mach 0.9 to 1.3 (transonic).  At Mach 1 and 45,000 ft conditions,  that would be 5000-6000 lb of drag at the very least,  even without considering that in the real world very few drag coefficients would be under 1.2 (not 0.4) at Mach 1 speeds.  The drag could easily be 3-4 times larger than those numbers. 

It is very important to understand that there are both specific impulse and frontal thrust density requirements that simultaneously must be met,  in order to achieve results in this scenario.  These have to be met on a trajectory that begins at zero speed,  vertical,  at sea level,  and that leaves the sensible atmosphere at about Mach 2 (2000 ft/sec),  still near-vertical,  at around 130,000 feet or so. 

                Trajectory averaged Isp, sec                       

                >1469/min payload         

                >4002/max payload

                Launch frontal thrust density, psf             

                >3900/min payload         

                >3900/max payload

                M=1 @ 45 kft net force density, psf         

                >3900/min payload         

                >3900/max payload

So,  what are the possible propulsion concepts,  and what are their characteristics,  as expressed in these terms?  For my bounding calculation,  I looked at technologies we actually have,  and at technologies we don’t actually have,  but which we could actually develop.  That excludes “Star Trek” warp and impulse drives,  and other similar things,  for which there exists no science.  The list is:

                Chemical rocket propulsion (as demonstrated,  not theoretical things which proved impossible)

                Nuclear-thermal rocket propulsion (including both solid and gas core concepts)

                Chemical airbreathers (ramjet,  gas turbine,  and scramjet)

                Nuclear airbreathers (nuclear scramjet)

                Nuclear pulse (explosion) propulsion (included with the rocket data as “rocket-like”)

Figure 2 contains the typical characteristics of three common chemical rocket systems,  the projected characteristics of multiple nuclear thermal rocket concepts as best we know them,  and the typical characteristics quoted for nuclear pulse propulsion as it was proposed circa 1959 during Project Orion.  There are all the rocket reaction propulsion concepts that we have,  aside from the extremely low-thrust electric concepts,  which are clearly not candidates for this application. 

The chemical rocket systems have the thrust density to take off vertically and accelerate upward,  but they lack the required specific impulse capability by a very large margin.  The one nuclear thermal rocket for which we have real test data likely cannot meet the thrust density requirement to take off and climb due to its low engine thrust/weight ratio,  plus,  it lacks the specific impulse capability to meet the needs of the low payload fraction case.

The gas core nuclear thermal rocket concepts are exactly that:  concepts.  None has ever been built and tested.  So the data are just best guesses.   These concepts very likely have much better engine thrust/weight ratios,  so that frontal thrust density requirements might be met,  as long as no waste heat radiator is required.   The closed-cycle gas core “nuclear light bulb” engine comes close to meeting specific impulse requirements with a clean exhaust for the low payload fraction case.  The open-cycle gas core engine definitely satisfies the impulse for the low payload fraction case,  but has a radioactive exhaust plume.  None meet requirements for the high payload fraction case,  for which the economics would be more feasible. 

Only nuclear pulse propulsion meets the impulse requirements and the frontal thrust density requirements,  and for both cases:  low and high payload fraction.  There are two very serious downsides:  the vehicle must be very large (over 5000 tons at launch,  preferably over 10,000 tons),  and the “exhaust stream” is quite literally a series of nuclear explosions in the atmosphere,  starting with a surface burst.  Not only is there radiation released,  there is a very destructive EMP.

 Figure 2 – Characteristics of Rocket and Pulse Propulsion Systems

Therefore,  of the rocket and rocket-like concepts,  only the “nuclear lightbulb” engine might possibly serve,  and then only if the weight statement can be adjusted to make 1300 sec Isp feasible.  This will be a difficult design to do,  without a lot of margin,  and with a reduced payload fraction that makes the economics more difficult.  Such a weight statement might be ascent inerts 0.40,  ascent propellant 0.50,  and payload 0.10,  remembering that “ascent inerts” includes on-orbit,  de-orbit,  and landing go-around propulsion that is not the nuclear ascent engine. 

The airbreathers are summarized in Figure 3.  At first glance,  the Isp’s of the ramjet and the gas turbines looks attractive,  but upon further inspection the frontal thrust densities are clearly not feasible.  Further,  the impulses are only attractive in a narrow band of speeds.  Variable inlets do not change this.

The ramjet depicted is a supersonic design with a minimum operating Mach number of 2,  which happens just as the vertically-launched spaceplane is leaving the sensible atmosphere somewhere above 100,000 feet.  A subsonic design that could ignite somewhere around Mach 0.7 and burn to about Mach 2-2.5 usefully,  but would have about half to two-thirds the listed impulse capability,  which renders it infeasible.  At altitude,  the frontal thrust densities are also completely infeasible,  unless these were staged-off strap-ons very much larger than the spaceplane’s fuselage.  It is staging we are trying to get away from here! 

Neither gas turbine design has the frontal thrust density to take off vertically at all,  so this kind of propulsion would also have to be gigantic strap-ons that get staged off.  Not feasible by definition. 

The basic message here seems to be that the airbreathers are very probably not very useful for vertically-launched fast ascent trajectories if no staging is allowable.  They might well be useful for a horizontal-takeoff,  depressed-trajectory design,  at the cost of enormous drag losses.  But that is a different scenario!

Figure 3 – Characteristics of Existing Airbreather Systems (Ramjet and Gas Turbine)

A nuclear ramjet is no better:  although its effective specific impulses are higher (you need to look at air specific impulse instead of fuel specific impulse to compare fairly,  the fuel air ratio embodied in the chemical ramjet data is .074),  the frontal thrust density is no better than the chemical ramjet.  It may well be worse due to the impact of a very heavy core on engine sizing.  Plus,  its exhaust stream is intensely radioactive,  based upon the Project Pluto nuclear ramjet ground tests decades ago. 

The best-guess estimates for scramjet characteristics are given in Figure 4.  These are impulse and frontal thrust densities similar to ramjet,  but achieved only at Mach numbers larger than 4,  the utter-minimum takeover speed.  These Mach numbers are simply incompatible with the vertical launch scenario.  The impulses look marginally-attractive in a narrow range of speeds,  but the frontal thrust densities at stratospheric altitudes are infeasible.  Going nuclear does not help the fundamental incompatibility  of a very high-speed airbreather on this trajectory.  Where the vehicle reaches these speeds,  there is no air!

Figure 4 – Guessed Data for Supersonic-Combustion Ramjet (Scramjet) Systems (Chemical and Nuclear)

So,  there are only two known propulsion concepts that could support a vertically-launched single stage spaceplane with operating characteristics of an airliner.  One is the “nuclear light bulb” version of the gas core nuclear thermal rocket,  which likely could support payload fractions around 5-10%,  if it actually existed,  which it does not.  What that really says is that this “nuclear light bulb” engine ought to be a major development priority.  It is not. 

The other is nuclear pulse propulsion,  which would only work in vehicle sizes far beyond anything ever before constructed,  and at the social cost of uncontained nuclear explosions in the atmosphere.  The EMP is probably actually more dangerous than the radioactivity,  but the radioactivity will be the political killer of this idea. 

So that leaves only the “nuclear light bulb” as a feasible propulsion for this kind of spaceplane.  But for vertically-launched fast ascent,  this looks to be entirely feasible.  Which means that its mythical engine should be a high-priority development.  

The only other approach to a single stage spaceplane to orbit would be a horizontally-launched craft with a depressed trajectory to make airbreathers feasible for a small portion of the ascent,  trading their impulse advantage against the enormous drag losses of flying fast down in the atmosphere.  The last program to attempt that approach was X-30,  which failed.  (It is very difficult to do realistic estimates for that kind of trajectory,  unlike this scenario.)  

PS:  The ramjet data were obtained with my latest version of the high-speed range cycle codes for sizing and performance.