Monday, August 22, 2022

Automotive Work

People who know me personally,  know about my rather-extreme vocalizations while I am working on cars and pickup trucks.  This first started many decades ago,  when I was doing all my own maintenance and repair to various air-cooled VW vehicles. 

It has gotten more vocal since.  The more modern vehicles have just made the effect worse,  because they are so damned hard to work on (too much crap piled into too little space),  and they have proven far less reliable in so many multiple ways. 

I have spent the last 3 years working in a repair shop (after coming out of retirement to do that for two friends) on all sorts of cars and trucks.  Whatever walks in the door.  What I have seen is two-fold.  I have now gone back into retirement in the summer of 2022.  And,  I do not want to come back out!

First:

Of the widely-available vehicles,  I have not seen very many Toyotas or Subarus in the shop.  I have seen a lot of Fords,  Chevys,  Dodges,  and Jeeps.  I have also seen quite a few Nissans,  Hondas,  and Hyundais.  If you are interested in reliability and low maintenance costs,  then Toyotas and Subarus are the cars to look at.  Period.  End of issue.  Volvos,  etc.,  don’t count,  there are so few of them out there. 

Second:

Of the ones I have seen more often in the shop,  generally speaking,  the later models after about 2005 are the ones which are noticeably less reliable.  This takes the form of computer and sensor failures,  not so much mechanical failures like brakes and wheel bearings,  transmissions,  or engine failures!  The late-model sophisticated electronics are just not as reliable as the mechanical components,  and that’s a fact,  Jack! 

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In point of fact,  you can no longer splice wires back together after a rat or squirrel has chewed them,  because the idiot computer cannot accept the change in wire resistance,  after you splice it!  That is totally ridiculous!  But true!  And quite expensive.   You have to replace the wiring harness.

And the manufacturers are making mistakes that they simply should not be making!  One example (of many) is the 2-piece spark plug that Ford introduced for a while in the late 1990’s and early 2000’s.  Why change something which has worked for over a century?  Ridiculous!  And very expensive to repair,  because it breaks apart when you try to remove the plug,  and it takes a special tool to get the broken stub out,  without enough room to work.

The Trend Toward Everything Computerized Is Bad

I am totally against this!  The term “artificial intelligence” (AI) is an oxymoron,  as far as I am concerned!  No computer is yet capable of responding to anything it has not been programmed for!  And the programmers simply do not know all the things the system must cope with.  And that’s another fact,  Jack! 

If the programmer did not anticipate something (and they so often do fail to anticipate common problems),  then people die in the real world,  as Tesla is learning so very reluctantly!  It’s utter bullshit to think otherwise!  Tesla is not alone in this mistake!  But they really have made this mistake!  It’s why they keep getting into trouble with the feds.

Don’t get me wrong:  Teslas are good cars!  Just do NOT use the auto-pilot feature!  It will get you killed,  sooner or later!

It's one thing to have a computer navigate for you.  I personally find that to be a serious driver failing,  but most folks today do not.  I like paper maps, myself.  But so be it.  It is quite another thing to have a computer drive your car for you,  while you dope off or nap.   That is what a computer cannot do,  unless and until it has been programmed for every possible contingencyMy contention is that we are still very,  very far from that!  That much is being proven by the current accident rates. 

There is (and has been for many decades) a garbage-in,  garbage-out law (GIGO law) relating to computers.  Computers quite happily process bad inputs,  and spit out the corresponding bad results data,  without any notation that they are processing bad input data.  That’s a very serious failing. 

You the human must be able to sort out the garbage output from the computer,  from the “good stuff” that is actually correct.  The only way to do that in a car is to drive the car yourself.  The current reliance on computer controls denies that unpleasant little fact of life.  And it is killing people!  So,  do not trust the computer!

I Recommend:

Dare trust nothing!  Learn to drive your car as if there were no automatic functions.  Do not trust any of the automatic functions,  except the automatic navigation functions.  Otherwise,  just do it for yourself.   

As for navigation,  look on the internet before you depart.  You may find the automatic navigation function is in some degree of error.  I usually find it delayed to the point of uselessness in real-time navigation,  myself.  Such as telling you to turn,  after you have already gone through the intersection. 

Warnings of exit and entrance ramps are too often delayed past the point of useful navigation.  You really have to be able to zoom in close on an internet map to see these things,  and once you are driving,  that is too late!

Do not buy a highly-automated car.  It’s just that simple.  Learn how to do it for yourself.  You will live longer.

 


Tuesday, August 9, 2022

FBI Raids Trump’s Mar-A-Lago Estate

see update 8-22-22 below

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Copied from the PBS News Hour website as of Aug 9,  2022:

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4 things to know about the FBI search of Donald Trump’s Mar-a-Lago estate

Politics Aug 9, 2022 4:37 PM EDT

 The FBI’s raid of former President Donald Trump’s estate on Aug. 8, 2022, caught Trump by surprise – and prompted immediate speculation about exactly why and how the law enforcement agency secured a search warrant.

“My beautiful home, Mar-A-Lago in Palm Beach, Florida, is currently under siege, raided, and occupied by a large group of FBI agents. … They even broke into my safe!” Trump said in a statement released through his political action committee, Save America.

Trump brought 15 boxes of classified materials with him to Mar-a-Lago when he left the White House, and delayed returning the materials to National Archives officials for months.

READ MORE: FBI searches Trump’s Mar-a-Lago estate

 The FBI and the Department of Justice have not commented on the raid, but the Justice Department is known to be investigating how Trump possibly mishandled government secrets. Trump is also facing other potential charges from the state of Georgia stemming from his alleged interference with the 2020 elections.

Georgia State University legal scholar Clark D. Cunningham, an expert on search warrants and the criminal investigations of interference in the 2020 election, explains what could have led to the raid and what the raid tells us about the state of the federal investigation into Trump’s activities.

1. There are legal hurdles to getting a search warrant

The U.S. Constitution requires that all search warrants “particularly describe the place to be searched and the … things to be seized.”

This requirement can be traced in part to a famous British case from the 1760s when agents of King George III searched the house of John Wilkes, an opposition member of Parliament, for incriminating papers. The warrant they used was condemned by the courts as a “general warrant” because it did not specifically name Wilkes, his house or the seized papers.

Courts and commentators also criticized the Wilkes warrant because it was based on mere suspicion. The U.S. founders looked to the Wilkes warrant as an example of what the Constitution should prevent and added the Fourth Amendment – requiring that search warrants only be issued “upon probable cause, supported by Oath.”

WATCH: Jan. 6 committee says Donald Trump is to blame for the violence

Criminal procedure laws help enforce these constitutional requirements by requiring search warrants to particularly describe “evidence of a crime … or other items illegally possessed.”

Only judges can issue search warrants, and they must find, based on sworn testimony, that there is probable cause that such evidence or items will be found in the location described in the warrant.

This means that a judge must have found that there was probable cause that either a crime had been committed, or that Trump was illegally possessing items taken from the White House. The FBI’s request for a search warrant might also have indicated concern that these documents would either be destroyed or moved off of the premises.

2. There are also potential policy hurdles

In February 2020, then-Attorney General William Barr announced new restrictions  that require the FBI and other law enforcement agencies to get permission from the Attorney General before investigating presidential candidates or their staff.

Barr’s successor, Attorney General Merrick Garland, has kept this policy in place – keeping in line with general Justice Department guidelines that try to prevent politically charged investigations.

This means that this search would not have taken place without Garland’s approval. Given the generally strong tradition of political independence at the Justice Department, it is not surprising that President Joe Biden and his aides were not informed in advance of the raid and found out on Twitter.

3. The FBI might have found more than it was looking for

The Supreme Court ruled in a 1990 case that police executing a warrant that authorized searching for the proceeds of a robbery could also lawfully seize weapons that were in plain view.

WATCH: Jan. 6 panel probes Donald Trump’s ‘call to arms’ on social media

Assuming that the FBI’s warrant authorized only searching for classified documents taken from the White House, if the FBI found “in plain view” other evidence of crimes related to the 2020 election or Jan. 6, 2021, Capitol insurrection, they likely could have taken that, as well.

4. There may be a connection with Trump’s possible election interference

A federal grand jury, requested by the Justice Department, has been investigating the presence of potentially classified documents at Mar-a-Lago since at least early May 2022. It seems likely that something has happened recently to cause this urgent search. One possibility is that the search warrant was issued based on information gathered in one or more of the criminal investigations involving 2020 election interference.

The Conversation

In particular, the Department of Justice on July 12, 2022, obtained a warrant to search the cellphone of John Eastman, Trump’s former lawyer. As hearings by the Jan. 6 House committee have revealed, Eastman was a primary architect of the plan to block Congress from certifying Biden’s victory.

There seems little doubt that the Justice Department had compelling, perhaps overwhelming, legal justifications for conducting this unprecedented search of a former president’s home. However, the secrecy required for Justice Department investigations and grand jury proceedings means that the country will have to be patient – the justifications for the search may become public only if and when criminal charges are filed.

This article is republished from The Conversation under a Creative Commons license. Read the original article.

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My Conclusions:

1.      Sounds like a very apolitical,  very well-executed (and proper) search warrant,  not anything at all like a “radical left witch hunt”.  Looks to me like the DOJ and FBI did this “right”. 

2.      It will be a while before we hear what they actually found,  and what legal jeopardy the former president might actually be in,  because of this.

3.     The fact that the probable cause evidence submitted to the judge was good enough to issue the search warrant,  suggests that a federal criminal indictment of Mr. Trump is more likely to follow,  than not.  Perhaps multiple indictments.  Perhaps not.  We will see.

4.     The pro-Trump extremists calling for civil war over this,  are committing treason,  in my opinion.

All that I know for sure is that,  in this country of late,  you get the best “justice” that your money can buy!  (And we-the-people need to fix that,  because it very definitely is not right!)  If I had mishandled classified information in my defense jobs 3-to-5 decades ago,  the way Mr. Trump did with his classified presidential records taken to Mar-A-Lago,  I would still be in prison today,  doing hard time. 

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Update 8-22-2022:

The warrant specifies searching for evidence for (1) violations of the espionage act (specifically mishandling classified materials),  (2) violations of the presidential records act (these must be given to the national archives,  not retained),  and (3) possible obstruction of justice.  

On the face of it,  the violations of the espionage act and the presidential records act seem pretty cut-and-dried self-proving as "guilty".  Those are federal felonies.  As for obstruction of justice,  we'll see.  It'll take DOJ a while to comb through all the stuff taken by the FBI,  and they will be reluctant to reveal what they find before the cases go to court.

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Thursday, August 4, 2022

Engineering Lander/Rover for Mars

 The following is a version of a paper submitted for presentation at the 25th Mars Society convention in Arizona,  in late October of this year (2022).  

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There are two common issues among the many modern plans for manned missions to Mars,  that are as yet totally unaddressed by all the probes and landers and rovers we have sent there over the last nearly 6 decades. Those are (1) a need for a large,  relatively smooth,  and rather flat landing area,  with a surface strong enough to support what we send there,  and (2) a source of ice from which to make drinking water,  breathing oxygen,  and even rocket propellants for the return flight home. See Fig. 1

Figure 1 – Site Requirements For A Manned Visit or Base of Any Kind

#(1) a need for a large,  relatively smooth,  and rather flat landing area…..

Only part of this can be adequately addressed by photography and other sensing from orbit:  “large”.  That issue becomes less important after there is an equivalent to GPS in orbit about Mars,  plus appropriate beacons installed at the landing sites.  None of that is there now,  so “large” it has to be,  to accommodate landing errors on the order of at least 5-10 km!   Orbital sensing can identify large sites.

The remote sensing enthusiasts will protest otherwise,  but in my opinion being absolutely sure about “relatively smooth,  and rather flat” is still not a possible thing to do reliably from orbit.   What we are worried about is meter-scale variations in slope,  meter-scale boulders,  and meter-scale erosion gullies.  At a larger scale,  that is the same sort of thing that nearly aborted or killed the Apollo 11 landing on the moon,  averted only by going to full manual control to search for an adequate touchdown site.

Some of the proposed vehicles to be landed,  and/or to be flown back off of Mars for the Earth return,  are quite tall and narrow in their proportions.  SpaceX’s “Starship” is one such.  As little as 10 degrees out of plumb can be enough to cause a tall,  narrow vehicle to topple over,  which is a guaranteed fatal explosion!  I have never seen anyone report 10 degree localized slopes from orbital sensing data

And having a landing leg come down on a boulder,  or down in a gulley,  by around meter or so,  is the same sort of risk,  except it is actually worse.  I’ve seen claims of being able to see from orbit boulders under a meter in size,  although I remain rather skeptical of that.  I have never seen anybody identify from orbit a gulley of only a meter scale!   See Figure 2 for how these risks calculate.

Figure 2 – Topple-Over Limits From Elementary Statics

Just for an example,  let us assume a vehicle with a pad span s near 11 m and a center-of-gravity height h near 25 m.  Let us assume the critical minimum dimension of the pad footprint d is 4.5 m.  The critical slope angle for tip-over is then just about a = 10 degrees,  which really isn’t such a large localized slope.  Assuming a typical dimension x = 1 m for boulders and gullies,  then for that same vehicle,  the resulting angle b is also just about 10 degrees.  Separately,  these are critical.  Combined:  even smaller is fatal!  Could that combined problem happen?  Absolutely!

So,  these are very real risks!  And,  on-site photography from a rover can identify them,  and precisely locate them.  That right there should tell you something about the need for this proposed mission!

Most of the successful landers on the moon and on Mars have had a span between the landing pads that was larger than the height to the center of gravity of the vehicle.  That pretty much eliminates the topple-over risk,  but it is not a feature of the SpaceX “Starship”,  nor any of the “Earth return vehicle” proposals I have seen from other companies.  Those are all tall and narrow.

…..with a surface strong enough to support what we send there

Regardless of the topple-over risk,  there is also the risk of a landing leg-and-pad stabbing into soft local regolith and burying that landing pad (or pads).  Usually,  landing pad size is quite limited,  and the static pressure exerted by any pad upon the local soil is the vehicle weight divided by the total pad area.  For the dynamics of touchdown,  the usual engineering practice is to at least double that static pressure!  If the vehicle in question is an Earth return vehicle,  you have to use the much larger fully-fueled weight for takeoff,  but you need not double it for the dynamics of touchdown.  There is another factor of 2 needed for modeling the effects of coming down out-of-plumb,  so that one leg hits first.  The higher factored pressure applies only to that pad.

If this exerted pressure at any given landing leg exceeds the bearing failure stress for the soil,  the leg and pad will sink into the soil,  and be buried.  If all legs exceed this critical failure pressure,  all will sink into the soil,  and the pattern of it will always be uneven,  leading also to a vehicle sitting out-of-plumb!  If tall and narrow,  such soil failure could then lead to topple-over,  and the resulting fatal explosion.

If the vehicle is an Earth return vehicle,  pads sinking into,  and buried by,  the local soil are also a very serious problem for takeoff.  There is both the weight of the soil atop the landing pad adding to the vehicle weight,  plus the added friction force required to extract the leg-and-pad buried in the soil.  Summed over the landing legs,  these can be large numbers,  comparable to the takeoff weight of the vehicle!  Digging the legs and pads out,  is thus a required activity,  and one with serious associated risks.

The problem on Mars is that well over 90% of the planetary surface seems to be fine,  wind-blown dry sand,  sometimes with rocks in it,  and sometimes not.  The critical failure strength of similar materials here on Earth is about 0.25 to 0.30 MPa,  with the maximum “safe” bearing pressure nearer 0.10 MPa.  That difference reflects the usual design safety factor of about 2.5 to 3 between failure and allowable.  

Why is this important?  Consider the crude estimates for SpaceX’s “Starship” at Mars,  that are given in Figure 3.  The vehicle has a bigger payload,  but little remaining propellant at landing.  It has a smaller payload and a full propellant load at takeoff for Earth return,  as shown.  

Figure 3 – Sizing Landing Pads

The static weights on Mars are quite different for landing and takeoff,  but the landing must be factored-up for the dynamics of touchdown, and for the possibility of touching down out-of-plumbwhere one pad hits first.  Such factoring is unnecessary for takeoff.  Using the soil failure pressure leaves no margin for design error,  giving an absolute minimum pad area requirement.  These pads are quite large for “soft fine sand”,  being about 2.55 m in diameter if there are 4 circular pads,  and about 2.08 m diameter if there are 6 circular pads.  We have seen nothing even close to such large landing pads on any of the “Starship” prototypes flown so far. 

There is just no way to determine the actual safe or failure bearing pressures on Mars,  from orbital sensing!  This can ONLY be done in-situ,  with some sort of a soil tester on a lander or a rover!  Period!  End of issue!  Nothing like that has ever been flown!  Not in all these decades!  That should also tell you something about the need for this proposed mission!

#(2) a source of ice from which to make drinking water,  breathing oxygen,  and even rocket propellants

Mars is quite dry,  because liquid water is not stable at such low atmospheric pressures.  There does seem to be a little moisture content to the regolith.  I have heard various numbers bandied about;  most commonly it is asserted that there might be 1 to 3% water content in the soil.  What that means is if you dig up and process a metric ton of regolith,  you will at best recover 10 to 30 kg of water.  That a lot of effort for a rather small return. 

And here is what that really means:  if you need one ton of recovered water over the course of a year,  you will have to process at least 30 to 100 tons of regolith.  For ten tons of water,  it’s 300 to 1000 tons of regolith.  For a hundred tons of water,  it’s 3000 to 10,000 tons of regolith.  For a thousand tons of water,  it’s 30,000 to 100,000 tons of regolith.   If you are making propellant for an Earth return vehicle,  your water requirement is closer to 1000 tons than it is 1 ton!   So,  you must deal with that!

This is not something you do with a shovel or a small backhoe.  This is a major effort with major pieces of machinery,  almost no matter the water requirement.  Soil moisture is not a very attractive resource.

By way of an alternative,  there are strong indications from orbital sensing that Mars might have some large deposits of buried ice,  with at least some of these deposits located near the lower latitudes that are feasible for a manned visit or a base.  Orbital sensing is not real ground truth,  but the odds seem good that the buried ice really is there at those sites.  What orbital sensing cannot tell you is how deeply buried the ice is,  how thick the deposit is beneath its cover,  or anything at all about the quality and purity of that ice.  

What that lack tells you is that you need some sort of a rover at each of those promising sites.  The rover needs a drill rig capable of at least 10-20 m depth,  and equipped for many repeat drillings!  That’s how you get real ground truth for the presence/absence of the buried ice,  how easy or difficult it will be to reach and extract it,  and what quality it is.  These properties affect drastically how much processing is required to utilize the resource,  and also what equipment you should bring to extract it.  See Figure 4 for a simple notion of why different equipment might be needed with varying site conditions.

Without that real ground truth in-hand,  it is entirely unethical to send a crew there and bet their lives on their being able to live off that uncharacterized resource!

Figure 4 – Different Methods For Different Depths To A Massive Ice Deposit

What should be on the rover

The rover with the highly-capable drill can also carry a soil tester.  Probably the easiest to implement would be a dropped-ball rig.  This rover should have a camera,  to do the photographic evaluations of local slopes,  boulder sizes,  and gullies,  and also to support the dropped-ball soil tester.  It should probably have a push blade on it,  to move boulders off of otherwise-nice spots. It wouldn’t hurt to have a beacon or two to deploy,  to help reduce the landing error for subsequent craft.

We already know from our experiences with the two nuclear-powered science rovers that aluminum wheels are a bad idea for moving across the sharp rocks of Mars. This engineering rover thing probably ought to have treads,  or at least tough steel wheels with big lugs on them.  It will have to “go-and-do” regardless of how daunting the sharp rocks might be!

It does need to be quite powerful,  especially if it is going to push boulders around and out of the way with that blade. It does not have to be really large,  just big enough to carry the drill,  soil tester,  and camera,  and to push fairly substantial rocks with the blade.  Depending upon just how much site preparation work this thing is actually expected to perform,  it might be wise to nuclear-power it.

You will note that no scientific instruments are proposed.  This is an engineering rover,  not a science rover!  It is intended to do the real engineering tasks required for a crew to safely visit any given site.  None of the science rovers have ever been asked to do that,  nor have they ever been equipped to do it.

Drill rigs we might “adopt,  adapt,  and improve” for this mission

The kind of drill needed for this mission drills quite deep (10 to 20 m) and multiple times.  There are no drills like that.  There are multiple drills being developed or proposed for lunar missions.  There is even one supposed to be aboard the ESA ExoMars mission,  since delayed.  NASA had one named ARADS they tested in the Atacama desert.  Most of these are quoted as able to drill 1 maybe 2 m deep.  There was once one able to drill 5-10 m deep,  but the Canadian company that created it no longer exists.  That was Deltion,  and the drill they were developing was commonly known as the “Canadrill”.  See Figure 5. This is the technology we need to resurrect,  and to develop further:  it needs to go deeper,  and it needs enough “reloads” to do this deep drilling several times.  

Figure 5 – The Canadian Mars Drill Technology Called “Canadrill”

The ExoMars mission may or may not ever actually fly.  It has a drill rover named Rosalind Franklin,  said be capable of 2 m depth.  The entire rover is said to mass 310 kg.  It carries some science instruments that this engineering rover may not need,  but would require a larger heavier drill rig to go much deeper.  All in all,  by the time we upsize the drill and add the soil tester arm,  plus a push blade for moving rocks,  and stout steel wheels with big lugs on them,  a good guess for the engineering rover is about 500 kg.

The dropped-ball soil tester notion

This is based on one of two test methods commonly used at construction sites to estimate safe soil bearing strengths for adequate foundation design.  The other is a press technology requiring more equipment.  This one is very simple,  but not as precise.  That doesn’t really matter:  even imprecise ground truth is far,  far better than no ground truth at all. 

As illustrated in Figure 6,  the tester is a dropped iron sphere,  held to an arm by an electromagnet.  The arm is articulated,  and can be moved.  The held ball and a camera are near its tip,  as shown.  The idea is to drop the ball from a known height,  and then measure the impact impression it makes in the soil.  The size of that impression allows you to estimate the impact force (and pressure) that created it.

The iron ball has a known diameter D and a known mass m,  so its weight W on Mars is precisely known.  Dropped from known height H,  it has a potential energy WH.  The work done Fh by the average impact force F upon the soil,  depends on the depth h of the impact impression.  That work must equal the potential energy of the ball,  so the average impact force is F = WH/h.  The diameter d of the circular impact impression allows one to estimate its area A = 0.25*pi*d2.   Because the ball is spherical,  there is a relationship between d and h:  if you measure one,  you can determine the other.  The average impact force divided by the area is the estimate of the soil bearing failure pressure that you desire.  The safe bearing pressure is that failure pressure,  divided by some appropriate factor of safety (2.5 to 3).  

With the camera on the end of the arm,  you look closely at the dropped ball.  The impression diameter d can be scaled in the image from the ball diameter D,  as indicated in the figure.  That determines the impression depth h from the spherical ball geometry.  And so the calculation proceeds.  The arm then recovers the ball,  guided by the camera,  by activating the electromagnet in close proximity.

Figure 6 – The Dropped-Ball Soil Bearing Strength Test

What the rover might actually look like

This will resemble other rovers,  being a wheeled body with instruments within,  and equipped with appropriate manipulation arms.  It will be different in that tough steel wheels are used,  which have big lugs on them for added traction,  plus a sort of mini-bulldozer blade on one end.  It needs fold-out solar panels,  but these need to be movable in order to dump off dust. 

My best guess is that the drill rig should operate off one side of the vehicle,  and the soil tester off the other side.  The solar panels should be at the other end from the push blade.  There should be spares on deck for drill bits,  and spares on deck for extra drill stem pipe,  plus spare soil drop test balls.  Any site beacons also go on the deck.  The only instrumentation should be that for analyzing the core samples from the drill rig.  See Figure 7

A key item for the soil tester would be to make scaling the impact impression diameter from the ball diameter in the camera image an automated process.  That will require programming skills that I lack.  But it would seem intuitively to be possible.

Figure 7 – What The Rover Layout Might Look Like

What the landed package might actually be

The MER missions (Opportunity and Spirit) had smallish rovers of about 185 kg,  released from a lander that massed some 348 kg.  Together,  the landed package was 533 kg,  pretty close to the 500 kg rover mass guessed above,  for this proposed mission.  What that says is that we need to delete the lander that had airbags and a righting arrangement,  in favor of something more like the “Skycrane” used by Curiosity and Perseverance,  except perhaps not so complicated.  Here is the MER mass statement:

The original MER missions had a cruise stage for course corrections,  all the way to Mars arrival (and direct entry off the interplanetary trajectory).  The package at entry interface was about 820 kg.  After the hypersonic aerobraking ended,  the heat shield was jettisoned and the parachute deployed,  so that the package was (just barely) subsonic as it neared the surface.  At 10-15 m altitude,  solid braking rockets attached to the parachute harness just above the backshell decelerated the package to a stop in midair,  and the lander/rover was released at that 10-15 m altitude.  It fell to an impact attenuated by airbags,  and the lander had means to deflate the airbags and then extend petals for self-righting.  Once righted,  the lander then released the rover.

What we might do here is add a few more small solid cartridges to the braking assembly on the parachute harness,  with a total thrust sized to simply hold up the package weight,  at the braking altitude,  for several seconds,  after the braking rockets burn out.  There is no lander,  only the rover.  It is released 10-15 m above the surface,  but on a cable-on-a-reel-and-escapement mechanism,  that limits its downward travel to about 0.5 m/s.  So,  we need the “weight-holding” thrust for about 30 seconds worst case,  to land the rover on its wheels at a safe speed.   No lander is needed,  and the rover thus can be near 500 kg,  for a package that otherwise falls within the MER mass statement.  Quite frankly,  I am surprised no one has thought of this simpler version of the “Skycrane” landing approach. 

See Figure 8 for a comparison of these landing strategies.  

Figure 8 – Comparison of Landing Strategies

What the cruise stage might be

I would suggest making the propellant tanks of the cruise stage slightly larger,  just to get a bit more delta-vee capability out of it,  maybe closer to 0.2 km/s delta-vee.  In that way,  we might get slightly-better landing accuracy,  and spend less time traversing the rover to exactly where we want it to be.  We might end up nearer 1200 kg than the MER 1063/1068 kg value,  but it would be worth it. Payloads that we can send to Mars are larger now.

See Figure 9 for a comparison of what the cruise stage designs might be.  Note that we are roughly-estimated at slightly under 1200 kg per vehicle sent to Mars. 

Figure 9 – Comparison of Cruise Stage Design Data

What launch vehicles might send this to Mars

Given a custom payload shroud of sufficient volume,  one Falcon-9 launch could easily send three of these 1200 kg probes to Mars in a single flight,  for which the listed payload capability is 4020 kg.  The website says the vehicle must be flown expendably to do this.  The Falcon-Heavy is listed as 16,800 kg to Mars flown expendably,  and so could carry 13 or possibly even 14 of these 1200 kg probes in a single launch.  Both rockets are flying right now.

Launch prices are still something of a guess.  If the Falcon-9 were priced at $120M per expendable launch,  then with 7 such launches you could cover some 21 potential landing sites on Mars,  with real ground truth.  That’s real ground truth for a launch cost of about $40M per site!  If the Falcon-Heavy were priced at $240M per expendable flight,  that’s some 13 sites evaluated for something like $18.5M launch cost per site. 

Folks,  that’s quite cheap!

Now,  the MER program spent something like $744 million on spacecraft development and launch,  and another $336M on some 15 years of mission operations.  We won’t need 15 years of operations with the engineering rovers.  But we will need to do at least some of the spacecraft development work again,  since we are eliminating the airbag-equipped,  self-righting lander in favor of a cable-reel-escapement mechanism,  to land a heavier rover without a lander at all.  And we will be building more than just 2 spacecraft to send to Mars.  Just for the sake of argument,  call it a $900M program.

7 Falcon-9 launches cover some 21 sites.  We need 21 spacecraft sent to Mars.  That’s somewhere close to $43M per site for spacecraft development and production.  That plus $40M per site launch cost is some $83M total per site for ground truth,  at some 21 sites!

1 Falcon-Heavy launch covers some 13 sites.  We would need some 13 spacecraft sent to Mars.  That’s about $69.2M per site for spacecraft development and production.  That plus $18.5M per site for launch costs is some $87.7M per site for real ground truth,  at some 13 sites.

Either way,  it’s still incredibly cheap!  See Figure 10.

Saving lives sent to Mars,  and saving money at the same time?  There is NO EXCUSE not to do this proposed mission!

Figure 10 – Estimated-Cost Data Per Site For Ground Truth

As a wild guess,  assume it will take 3 years to decide which drill can be scaled up for 20 m depth,  and then get that job done.  Assume also that it will take 3 years to develop the 500 kg rover with the lugged steel wheels,  the drill,  the soil tester,  and the instruments and controls that make it autonomous.  That can be done in parallel.  Assume also that it will take 2-3 years to dig out the MER cruise stage plans and update them for more delta-vee,  as I suggested above.  That can also be done in parallel. 

We cannot make a 2024 launch window,  but we could make a 2026 launch window.  That means we start getting on-site ground-truth data in 2027.  That’s just in time to aid anything going to Mars in 2028 or later.

Somebody really needs to get on with this war!  See Figure 11.

Figure 11 – Wild Guess Program Schedule

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A final thought:  this really needs to be done on the moon,  too.  And,  pretty much anywhere else we might go.