On Economic Depressions and Public Policy

I think there is a demonstrated history going back to the 1930's that you do not want to try “hands-off” policies, much less austerity, during a depression, you really do want your government to spend, even if it's deficit spending. The basic concept is for the government to spend what it can, when no one else will. If no one spends, the economy grinds to a complete halt and stays depressed for several years. We saw this in the US of the 1890’s and the 1930’s. We’re seeing it again in Europe, where the banks doing the bailouts are insisting on extreme austerity, thus making bad unemployment even worse.

On the other hand, there has been plenty of evidence for centuries that in the good times, you want to run budget surpluses, so as to build up cash reserves. Such reserves allow you to spend in the bad times with much less borrowing required. Too much debt leads to an interest payment crisis just down the road. The US Congress has completely failed to run budget surpluses, dating all the way back to the good times we had in the 50's and 60's. (It is their constitutional responsibility to pass budgets.)

The third piece of that puzzle is that too-large a debt burden is unsustainable. The Europeans are now learning this lesson the hard way, and we are about to, here in the US. There is no magic to it, it's simply the math of compound interest. Unsustainable debt comes about by excessive borrowing to finance deficit spending, carried on for too long. Your only other option would seem to be printing excessive amounts of paper money, but that’s a bad thing, too.

The fourth piece of this puzzle is that you can’t finance deficits by printing excess money instead of borrowing, for that very quickly drives up inflation very dramatically, and it quickly goes completely out of control, just like 1920’s Germany, and to a lesser extent, the late 1970’s US. I remember 1979's 18.5% per year inflation with a very bad taste in my mouth.

Since neither borrowing nor printing money can “solve” the problem of chronic deficits, the only sane option is just not to run chronic deficits. Do it only during temporary emergencies like wars and depressions.

All that being said, there is a very good reason to believe that neither party's ideologies about the economy are worth a damn as public policy, or that either of them ever had much to do with the severity of what has happened to us economically in recent decades. But fuel prices did.

This country's economy was "designed" (over the last couple of centuries, mostly by the dead hand of Adam Smith, and the rest by the random action of ignorance and neglect) to run on dirt-cheap energy. Since 1973, every major economic downturn (1974, 1979, and 2001) is associated with high fuel prices.

In this context “high fuel prices” is roughly characterized as about $2.50-to-3.00/gallon for gasoline, when expressed in today's dollars, i.e., corrected for inflation. This indicator is important because our economy is much more consumer-driven, and consumer fuel demand is not very much a matter of choice: you still have to drive to work, school, and the grocery store, regardless of price.

Historically, what we remember as “good times” are associated with low fuel prices, which in today's dollars are invariably near $1.75-$2.00/gallon gasoline. Go to my earlier two articles "Oil Prices, Recessions, and the War" dated 2-4-11, and "Iran, Oil, and Economies" dated 3-8-12.

Both articles use an inflation-corrected gasoline price curve versus time from zfacts.com, as was available at each date. I modified these curves to show more current events than zfacts.com did. If you look at the 1958 price of 25-26 cents a gallon in Texas, and use factor-7.5-to-8 for inflation (pretty well-accepted) from then to now, the supply-and-demand price should be just about $1.75-$2.00/gal today. That is, they would be, if oil products really were, and are, a "market-driven" competitive commodity.

They are so very clearly not. They have not been since US oil production peaked and OPEC rose to dominate the oil market in the early 1970’s. Since then, superposed over the basic supply-and-demand pricing, there have been, and still are, frequent large, greed-driven speculator bubbles that burst, and there are huge monopoly cartel punitive pricing spikes, whenever we anger some part of OPEC.

For example, Reagan's "trickle-down" economics is still widely believed by too many to have finally ended the so-called "Carter stagflation years" just about 1986 in his second term. But that's not what really ended it. The Iran-Contra deal gave Iran the weapons they wanted. That deal ended the punitive OPEC pricing spike that started with the Iran hostage crisis in 1979 during Carter's administration. That OPEC punitive pricing spike is what really caused the "Carter stagflation years" to begin with.

My point: government economic policies are quite apparently nothing but a "fine-tuning" control that pales into insignificance when compared to the "channel-changer" that is fuel prices.

By the way, there was no fuel price spike after the 1991 Gulf War invasion of Iraq, because the rest of OPEC actually begged us to do that. Which absence proves my point.

The real trouble facing us is that OPEC production has also just about peaked, which means for the first time in history that world oil supply will begin to fall short of spiraling world oil demand. For those who disbelieve my contentions about “peak oil”, see my original article on the Bakken resource “Drill here, drill now, pay less?” dated 3-14-10. See also my follow-up article “Surprise, Surprise! Oil Boom in the Williston Basin” dated 9-5-11, that takes into account why there is an oil boom going on right now in North Dakota, but also why it is no long-term solution to our fuel demand and pricing problems.

That peak oil effect will destabilize the long constant trend of inflation-corrected supply-and-demand pricing, a constant that has underlain the various price spikes since the 1970’s. It will hence drive this underlying supply-and-demand price ever-higher, even if there were no more speculator bubbles and OPEC monopoly-pricing spikes (those just make things even worse).

Even when Afghanistan is done, and we have no armies stationed anywhere in the middle east, I predict we will never again see prices back down to $2.00/gallon, because China and India are industrializing, and there will very soon be insufficient oil to support both them and us, if it has not already happened. I think the supply shortfall relative to demand has already started. But that’s just my opinion.

According to historical precedents, it takes around 30 to 50 years for one industry to fully replace another in the free market, without some kind of government tax penalty/incentive/subsidy intervention (and all the perils and pain those typically pose). We should have started replacing oil in the 1970’s, around 40 years ago, when we first had the chance. Alas, greed for short-term profit was too strong in the halls of Congress. Now we're going to have to do it fast-and-painful.

And still, almost no one sees it coming, not even today. Because they don't want to see it. Truth can be very uncomfortable, even painful. But it does set you free. Deception, even self-deception, doesn't.

"Cassandra" has spoken.

GW

Update 1-3-15:

The recent explosion of US “fracking” technology (hydraulic fracturing plus horizontal-turn drilling) has modified the picture of oil prices versus recessions.  Unexpectedly,  the US has become a leading producer of crude oils for the world market.  Plus,  there has been an associated massive production increase and price drop in natural gas.

OPEC has chosen to take the income “hit” and not cut back their production in response.  Their reasoning is twofold:  (1) fear of loss of market share,  and (2) hope that low oil prices will curtail US “fracking” recoveries.  We will see how that plays-out.

Oil prices are now such (at around $55/barrel) that US regular gasoline prices are nearing $2.00/gal for the first time in a very long time.  This is very close to the price one would expect for a truly competitive commodity,  based on 1958 gasoline prices in the US,  and the inflation factor since then. 

It is no coincidence that the exceedingly-weak US “Great Recession” recovery has suddenly picked up steam.  The timing of the acceleration in our economic recovery versus the precipitous drop in oil prices is quite damning.  There can be no doubt that higher-than-competitive-commodity oil prices damage economies.  Oil prices are a superposition of the competitive commodity price,  overlain by an erratic increase from speculation,  and further overlain quite often by punitive price levels when OPEC is politically unhappy with the west.  That’s been the history. 

This economic improvement we are experiencing will persist as long as oil,  gas,  and fuel prices remain low.  (Government policies have almost nothing to do with this,  from either party.)  How long that improvement continues depends in part upon US “fracking” and in part upon OPEC.  Continued US “fracking” in the short term may depend upon adequate prices.  In the long term,  we need some solutions to some rather intractable problems to continue our big-time “fracking” activities. 

The long-term problems with “fracking” have to do with (1) contamination of groundwater with combustible natural gas,  (2) induced earthquake activity,  (3) lack of suitable freshwater supply to support the demand for “fracking”,  and (4) safety problems with the transport of the volatile crude that “fracking” inherently produces. 

Groundwater Contamination

Groundwater contamination is geology-dependent.  In Texas,  the rock layers lie relatively flat,  and are relatively undistorted and unfractured.  This is because the rocks are largely old sea bottom that was never subjected to mountain-building.  We Texans haven’t seen any significant contamination of ground water by methane freed from shale.  The exceptions trace to improperly-built wells whose casings leak.

This isn’t true in the shales being tapped in the Appalachians,  or in the shales being tapped in the eastern Rockies.  There the freed gas has multiple paths to reach the surface besides the well,  no matter how well-built it might have been.  Those paths are the vast multitudes of fractures in the highly-contorted rocks that subject to mountain-building in eons past.  That mountain-building may have ceased long ago,  but those cracks last forever. 

This is why there are persistent reports of kitchen water taps bursting into flames or exploding,  from those very same regions of the country.   It’s very unwise to “frack” for gas in that kind of geology.

Induced Earthquake Activity

This does not seem to trace to the original “fracking” activity.  Instead it traces rather reliably to massive injections of “fracking” wastewater down disposal wells.  Wherever the injection quantities are large in a given well,  the frequent earthquakes cluster in that same region.  Most are pretty weak,  under Richter magnitude 3,  some have approached magnitude 4. 

There is nothing in our experience to suggest that magnitude 4 is the maximum we will see.  No one can rule out large quakes.   The risk is with us as long as there are massive amounts of “fracking” wastewater to dispose of,  in these wells.  As long as we never re-use “frack” water,  we will have this massive disposal problem,  and it will induce earthquakes. 

Lack of Freshwater Supply to Support “Fracking”

It takes immense amounts of fresh water to “frack” a single well.  None of this is ever re-used,  nor it is technologically-possible to decontaminate water used in that way.  The additives vary from company to company,  but all use either sand or glass beads,  and usually a little diesel fuel.  Used “frack” water comes back at near 10 times the salinity of sea water,  and is contaminated by heavy metals,  and by radioactive minerals,  in addition to the additives.  Only the sand or glass beads get left behind:  they hold the newly-fractured cracks in the rocks open,  so that natural gas and volatile crudes can percolate out. 

The problem is lack of enough freshwater supplies.  In most areas of interest,  there is not enough fresh water available to support both people and “fracking”,  especially with the drought in recent years.  This assessment completely excludes the demand increases due to population growth.  That’s even worse.

This problem will persist as long as fresh water is used for “fracking”,  and will be much,  much worse as long as “frack” water is not reused.  The solution is to start with sea water,  not fresh water,  and then to re-use it.  This will require some R&D to develop a new additive package that works in salty water to carry sand or glass beads,  even in brines 10 times more salty than sea water. 

Nobody wants to pay for that R&D. 

Transport Safety with Volatile “Frack” Crudes

What “fracking” frees best from shales is natural gas,  which is inherently very mobile.  Some shales (by no means all of them) contain condensed-phase hydrocarbons volatile enough to percolate out after hydraulic fracturing,  albeit more slowly than natural gas.  Typically,  these resemble a light,  runny winter diesel fuel,  or even a kerosene,  in physical properties.  More commonly,  shale contains very immobile condensed hydrocarbons resembling tar.  These cannot be recovered by “fracking” at all. 

The shales in south Texas,  and some of the shales and adjacent dolomites in the Wyoming region actually do yield light,  volatile crudes.  The problem is what to transport them in.  There are not enough pipelines to do that job.  Pipelines are safer than rail transport,  all the spills and fires notwithstanding. 

The problem is that we are transporting these relatively-volatile materials in rail tank cars intended for normal (heavy) crude oils,  specifically DOT 111 tank cars.  Normal crudes are relatively-nonvolatile and rather hard to ignite in accidents.  DOT 111 cars puncture or leak frequently in derail accidents,  but this isn’t that serious a problem as long as the contents are non-volatile.  These shale-“frack” light crude materials resemble nothing so much as No. 1 winter diesel,  which is illegal to ship in DOT 111 cars,  precisely since it is too volatile. 

The problem is that no one wants to pay for expanding the fleet of tougher-rated tank cars.  So,  many outfits routinely mis-classify “frack” light crudes as non-volatile crudes,  in order to “legally” use the abundant but inadequate DOT-111 cars.  We’ve already seen the result of this kind of bottom line-only thinking,  in a series of rather serious rail fire-and-explosion disasters,  the most deadly (so far) in Lac Megantic,  Quebec. 

Volatile shale-“fracked” crudes simply should not be shipped in vulnerable DOT 111 cars,  period.  It is demonstrably too dangerous. 

Conclusions

“Fracking” shales for natural gas and light crudes has had a very beneficial effect on the US economy and its export-import picture.  We should continue this activity as a reliable bridge to things in the near future that are even better. 

But,  we must address the four problem areas I just outlined.  And I also just told you what the solutions are.  The problem is,  as always,  who pays.   What is the value of a human life?  What is the value of a livable environment?  It’s not an either-or decision,  it’s striking the appropriate balance!

Lethally-Dangerous Riots at US Embassies

Now that some time has passed since the fatal attack on our embassy in Libya, the picture gels. There really was a terrorist plan, even though some officials do not want to admit that. Here is my best guess as to what it was (and still is).

Update 9-25-12: I have seen nothing reported since that would induce me to change my original assessments or my original recommendations. Aficionados of political correctness could substitute the word "dangerous" for the word "uncivilized", but they would lose a little of the real meaning of my assessments. I choose not to "dumb it down" that way.

One of the Al Qaeda groups noticed a video on YouTube about a movie that was made by anti-Muslim Christian extremists. The terrorist group then pointed it out to their followers online, specifically timed with their planned terrorist attack in Libya.

Their intent was (and still is) for a wave of “spontaneous” dangerous riots to follow, which outwardly resemble their attack. These are “spontaneous”, in that they didn’t have to foment them overtly. It continues all over the Muslim world, and has shown up over here with bomb threats causing evacuations at UT Austin and NDSU.

Why Does This Happen?

Science says any belief system, religious or political, can be intensified to the point that super-strong belief simply trumps all reason and law. It’s an emotional thing. The more fundamentalist the religion or the more rigidly-ideological the politics, the easier it is for this to happen. It’s really bad when the two are mixed together intimately, as is now “customary” in the Middle East.

Once you have a population of extreme religious (or political) nuts, two bad things happen: (1) any disagreement from outside the group is emotionally taken as an intolerable insult, and (2) the fanatical believer is very easily induced to commit any atrocity in the name of whatever it is he believes in. That’s where all the rioters and demonstrators come from.

We Still Have a Serious Terrorist Enemy

The professional terrorists, such as the original Al Qaeda central command, make use of this. They are not religious nuts, but they do masquerade as such. They use the intense-believer phenomena to recruit large numbers of fanatical followers willing to commit violence, including suicide bombings. But, did you also notice that the Al Qaeda command leaders never wore the suicide vests themselves, which proves my point about who and what they are.

Unfortunately for us, Al Qaeda has decentralized to multiple separate second-tier terrorist commands (such as Al Qaeda in the Arabian Peninsula in Yemen). They inspire many small follower groups all over the Muslim world and elsewhere, all fanatic enough to carry out the same recipe for violence, more-or-less independently. Basically, it has metastasized all over the world like a cancer.

Also unfortunately for us, there are rich recruiting grounds for violent followers throughout most of the Muslim world (or Third world, which is pretty much the same). This is because the bulk of those populations are both poor and uneducated.

Folks like that hate complexity in anything, and so prefer the simplicity of a harsh black-or-white moral prescription from an extreme fundamentalist religion, or from a dictatorial government, or both. They are therefore extremist in their belief, and thus very susceptible to terrorist suggestions.

What Do We Do About It?

We have a list of terrorist organizations, and more usefully, a list of the state sponsors of terrorism (they actually do have addresses). We should make better use of them. We should tie our foreign policy responses, as well as the prospects of foreign aid, to those lists. Several of our so-called “friends” in the region should be on one or both lists.

I think we need a third list, though, one that ranks how “uncivilized” a country is. Uncivilized people cannot channel their anger (justified or not) into anything but violence, unlike civilized people. Much of the middle east is still rather uncivilized, which is why there are so many screaming mobs always getting offended, rioting, and killing. It is also why our two attempts at planting democracy over there have not turned out well.

Using The “Uncivilized” List

If we intend to maintain a diplomatic presence in one of these uncivilized countries, then our embassy must be capable of defending itself against the screaming mob, however it starts. That means a large contingent of very heavily-armed Marines. If the mob comes through the gate or over the wall, we gun them down. Period. Raw naked force is something even a howling, uncivilized mob will understand.

An uncivilized country is not one in which we should consider any kind of extended “boots-on-the-ground” operation. The reason for any such an operation is irrelevant to that consideration. It should be only “get in fast, kill bad guys, and leave immediately.” We should never try an occupation again in places like Afghanistan and Iraq. Recent history says very clearly that it’s just a waste of our treasure and our kids’ lives.

If there’s a terrorist group or state sponsor to hit in one of these places, then I say hit it hard. But, use long-range weapons from a great distance. Kill the bad guys. Give them no chance to hurt us. The population in the midst of which these bad guys lived will be “inconvenienced”, to say the least. But, that’s the penalty they should incur for being uncivilized, and for harboring or sponsoring terrorists.

NewMars Forums

For my NewMars forum correspondents: I need help. Somehow, I cannot find the forums page to sign on ("page not available" and "error 404"). Did someone block me somehow? If so, by mistake, I hope?

GW

update: 9-19-12

The access issue has been resolved. I don't know what happened there, but I was not the only one who saw the error messages.

Other stuff:

NewMars forums guys who spot this message might want to peruse two articles just below. The one dated 8-23-12 is the design rough-out for a manned chemically-powered lander for Mars, plus an unmanned cargo-only variant of the same vehicle. This is a rough-out to the level of mass statement and volume reconciliation. It's a useful startpoint for a real design process, and it is "in the ballpark" as regards performance. These designs move between low Mars orbit and the surface.

The article dated 9-3-12 defines the configuration changes and estimates the performance of that same basic lander used instead at Mercury. One can delete the heavy heatshield, and most of the aeroshell, but one must still add extra propellant for the airless descent. Mercury is somewhat similar to Mars in size and gravity, but utterly airless. No entry deceleration there.

However, the final answer is that both the manned and unmanned cargo landers designed for Mars could actually be used successfully at Mercury. This is MMH-NTO storable propellant stuff, and these are one-shot throwaway vehicles, same idea that we used decades ago on the moon.

More of this is in the works. Our moon, the big moons of Jupiter and Saturn, the largest 4 asteroids. I just have to find the time to get it done. But, I expect the one basic design, reconfigured for each site, could be used quite successfully.

Eventually, I want to run a similar design family based on nuclear thermal rocketry, that is fully re-usable. Over the long haul, that would be the better deal from a bang-for-the-buck standpoint.

Revised Launch Cost Update

Update 4-8-2024:  Should any readers want to learn how to do what I do (estimating performance of launch rockets or other space vehicles),   be aware that I have created a series of short courses in how to go about these analyses,  complete with effective tools for actually carrying it out.  These course materials are available for free from a drop box that can be accessed from the Mars Society’s “New Mars” forums,  located at http://newmars.com/forums/,  in the “Acheron labs” section,  “interplanetary transportation” topic,  and conversation thread titled “orbital mechanics class traditional”.  You may have scroll down past all the “sticky notes”. 

The first posting in that thread has a list of the classes available,  and these go far beyond just the two-body elementary orbital mechanics of ellipses.  There are the empirical corrections for losses to be covered,  approaches to use for estimating entry descent and landing on bodies with atmospheres,  and spreadsheet-based tools for estimating the performance of rocket engines and rocket vehicles.  The same thread has links to all the materials in the drop box. 

The New Mars forums would also welcome your participation.  Send an email to newmarsmember@gmail.com to find out how to join up.

A lot of the same information from those short courses is available scattered among the postings here.  There is a sort of “technical catalog” article that I try to main current.  It is titled “Lists of Some Articles by Topic Area”,  posted 21 October 2021.  There are categories for ramjet and closely-related,  aerothermodynamics and heat transfer,  rocket ballistics and rocket vehicle performance articles (of specific interest here),  asteroid defense articles,  space suits and atmospheres articles,  radiation hazard articles,  pulsejet articles,  articles about ethanol and ethanol blends in vehicles,  automotive care articles,  articles related to cactus eradication,  and articles related to towed decoys.  All of these are things that I really did. 

To access quickly any article on this site,  use the blog archive tool on the left.  All you need is the posting date and the title.  Click on the year,  then click on the month,  then click on the title if need be (such as if multiple articles were posted that month).  Visit the catalog article and just jot down those you want to go see.

Within any article,  you can see the figures enlarged,  by the expedient of just clicking on a figure.  You can scroll through all the figures at greatest resolution in an article that way,  although the figure numbers and titles are lacking.  There is an “X-out” top right that takes you right back to the article itself. 

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My best take on current and near-term predicted launch costs was posted 5-26-12 on this site as "Revised, Expanded Launch Cost Data". Today, I found an NBC news story on NASA's best estimates for launch prices on its SLS giant launch rocket, yet to be developed. Using their data, I computed payload unit prices as delivered to LEO from Canaveral. Here are three excerpts from the NBC story with the essential data:

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By Mike Wall

updated 9/13/2012 12:08:52 PM ET

The giant rocket NASA is building to carry astronauts to Mars and other destinations in deep space may cost $500 million per launch when it's flying regularly, space agency officials said Tuesday.

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In its initial incarnation, the SLS will be capable of lifting 70 metric tons of payload. But NASA eventually plans to build several variants of the rocket, allowing it to carry 105 tons in one configuration and 130 tons in another.

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"We can move from one configuration to the other configuration with not a lot of cost," Bill Gerstenmaier, NASA's associate administrator for human exploration and operations, said Tuesday at the SPACE 2012 conference.

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The basic message from this is essentially-constant launch price for 3 payload levels ranging from 70 to 130 metric tons. I added those data to the data plotted in my 5-26-12 "Revised, Expanded Launch Cost Data" posting. The revised figures are given below (Fig 1 for US units, Fig 2 for metric mass units, both in US dollars).

-- Oops,  got the figure titles and callouts backwards in terms of units.  Sorry.  Just noticed it and fixed it today,  9-28-12.  Changes in bold type.  


Figure 1 -- Updated Revised Launch Costs (lbm basis)


Figure 2 -- Updated Revised Launch Costs (kg basis)

Looking at either revised figure, if one extends the two trend lines for the Spacex Falcon family and the SLS "family", it is clear that SLS would be around 4 times more expensive per unit mass than the Falcon family, or actually any of the commercial expendable launchers. That is exactly the factor I estimated in the 5-26-12 posting.

Furthermore, a trend curve of the same shape as the Falcon family, drawn through the SLS data, would come pretty close to the Titan-IV data point, another vehicle in the "government project" class (as discussed in the earlier posting). This also helps confirm the conclusions drawn then. This applies to both the government vs commercial vertical expendable launch vehicles comparison, and to the spaceplane vs vertical expendable launch vehicle comparison (as based on "government" vehicles).

Thus, the conclusions I drew in that 5-26-12 posting are thus independently confirmed by NASA's own published estimates. Compared at the same payload mass, under the assumption that max payload is flown, "typical government" expendable launchers are definitely around factor 4 more expensive than expendable launchers competing in the private launch market. The essential difference is smaller logistical "tail" typical of commercial competitive systems.

This also leaves my conclusion about spaceplanes still valid: about 2-3 times more expensive than expendable vertical launch rockets, when compared at constant max payload. That does still imply a lower launch cost than "typical" expendable vertical launch rockets, when restricted to small max payloads.

A major change in technology (such as Skylon) would be required to change this picture significantly, due to the smaller launch-basis payload mass fraction generally available in a spaceplane, as compared to an expendable vertical launch rocket.

The other "wild card" is the reusable vertical launch rocket, which might be cheaper than the expendable version, all else being equal. Whether that can really be achieved, remains to be seen.

Results with Space Shuttle SRB solid-propellant booster rockets were not all that encouraging, because they had inherently-higher inert mass fractions than typical liquid fuel booster stages, and they had a significant non-reusable rate, most of which was attributable to ocean impact forces.

Neither are the Falcon-9 results to date very encouraging. None of these have been deemed reusable, due to a combination of re-entry air load damage, and ocean impact damage.

How any of this might impact launch costs is completely undetermined, as of this date.

For Neil

Farewell Neil Armstrong. May you always have fair skies and following seas. Thank you for your expertise, your bravery, and your shining example.

GW

Using the Chemical Mars Lander Design at Mercury

Scope and Purpose

The one-shot chemical Mars lander design of reference 1 was reanalyzed to see if it could be made to serve the same role effectively at Mercury (it can). Since Mercury is airless, descent from a low circular Mercury orbit of 100 km altitude was assumed. All analyses assume descent from circular orbit, not high-speed direct descent from an interplanetary transfer orbit. Analysis methods are nothing but pencil-and-paper rocket equation calculations, with some judgmental factors thrown in, to ratio ideal velocity increments up to actual required velocity increments. While crude, these results are most definitely “in the ballpark”.

Velocity Requirements

Velocity requirements were determined from the data in reference 2 for a 100 km circular orbit altitude at Mercury. The basic data from the spreadsheet analysis are given in Figure 1 for all of the destinations of interest, not just Mercury, and also including Earth as a reference. These destinations of interest include Mars, Mercury, and Earth’s moon in the inner solar system, the 4 large airless moons of Jupiter, plus Titan with its dense atmosphere at Saturn, and the four largest known asteroids in the main asteroid belt. All figures are at the end of this article.

As a reference point, I used 5% nominal drag loss for a slender ascent vehicle on Earth, and 5% gravity loss for the typical ascent at modest gee. These typical Earth drag losses were ratioed by the surface air density at destination to the surface density at Earth. (I ignored the fact that these descent vehicles are not slender, while the ascent vehicle is.)

The typical Earth gravity losses were ratioed by the relative surface gravity of the destination to that of Earth. These results are given in Figure 2. The final one-way delivered velocity requirements are shown in Figure 3 (along with the drag coefficient scaling column from the original spreadsheet, just to be complete). That figure also shows a higher requirement reflecting an extra 2.8% velocity margin. For Mercury, ascent and descent vehicles should be capable of delivering over 2.944 km/s, and ideally nearer 3.027 km/s.

The Original Mars Lander Design of Reference 1

These data are repeated here for direct comparison only. The ascent vehicle was a one-stage device with a crew cabin that doubles as an abort capsule. It is fueled by monomethyl hydrazine and nitrogen tetroxide (MMH-NTO) storable propellants. The ascent vehicle engines are canted 10 degrees for retro plume stability in Mars’s atmosphere, and also serve as the descent engines. The crew cabin / abort capsule is loosely based on the Spacex Dragon without its trunk module. It is intended to carry 3 astronauts plus a lot of propellants to support the abort scenario, and features a much thinner, lighter heat shield than the “standard” Dragon. This ascent vehicle is illustrated in Figure 4.

The descent vehicle comprises a basic frame plus cargo deck, a heat shield that is dropped once the hypersonics end at about Mach 3, extendible landing legs, an aeroshell (portions of which double as unload ramps), and descent propellant tanks plus cargo modules anchored to the cargo deck floor. These descent propellant tanks feed the ascent vehicle engines for a direct rocket-braking touchdown on Mars, without resort to any aero-decelerator devices. This is because end-of-entry occurs at too low an altitude: there is not enough time remaining to deploy an aero-decelerator of any type, much less have it do any good. This vehicle is depicted in Figure 5. It weighs 60 metric tons at entry, carries 3 astronauts plus 5.943 metric tons of cargo (equipment, supplies, etc).

It should be noted that the de-orbit burn from low Mars orbit is about a 50 m/s velocity increment. At this level of analysis, that is negligible. Similar very low values would also obtain at the other destinations of interest. Such a burn can be accomplished with nothing more than attitude-control thrusters.

It should be noted that the Mars lander is a dead-head payload item for any orbit-to-orbit transit vehicle going to Mars. Each lander taken on the Mars mission is thus a 60 metric ton payload item. If multiple landings are to be made in one mission, then it is likely that the mass of the landers could exceed the mass of the habitat and supply storage modules for a crew of 6, but that is a problem for the transit vehicle design, and out of scope here.

It should also be noted that these landers are items that must be assembled in low Earth orbit from components that must fit within the payload shrouds, and within the mass limits, of available launch rockets. In the near term, those would include the Atlas-V and Delta-IV families, Falcon-9, and starting next year, Falcon-Heavy. Considerable assembly in orbit is required. This is a separate topic.

Modifications for Use at Mercury

At Mars, most of the descent velocity increment is accomplished by hypersonic aerodynamic drag. This cannot be done at airless Mercury, indeed, there is no need for a heat shield at all. Extra propellant must be added for a rocket braking descent of the kind used by Apollo at the moon. The heat shield can be deleted, saving about 7 metric tons in this design. Most of the aeroshell can be deleted, except for a couple of panels that serve as unload ramps. That might save another half a ton, but that is ignored.

Using Basically the Same Ascent Vehicle at Mercury

The ascent velocity requirement at Mercury is a little smaller than that at Mars, so a small amount of the ascent vehicle propellant may be used during descent, and still meet some safety margin on ascent. I got an approximate value of 2.728 tons for this ascent vehicle propellant reallocation. Otherwise, the very same ascent vehicle used at Mars may be used at Mercury. That vehicle is depicted in Figure 6. Its mass at ascent ignition is a bit lower (compared to Mars) at 19.939 metric tons. There is no change at all to the vehicle’s structure.

Descent Vehicle Modifications for Use at Mercury

The original Mars descent configuration carried 15.390 metric tons of descent propellant in tanks secured to the cargo deck inside the very voluminous aeroshell. That scheme was expanded to six tanks 2 m in diameter by 2.84 m cylindrical length, at a volume ratio of 90%, and an inert mass fraction (loaded tank basis) of 4%. That puts 60.390 tons of propellants on the cargo deck, plus the small allocation from the ascent vehicle tanks, for a total of 63.118 tons of descent propellant, and a total mass of 97.573 tons at start of descent from orbit. There is still plenty of deck space available for cargo.

I had to reduce the cargo mass a little bit, to 3 metric tons, before I could show some velocity increment safety margin in descent. That would be 3 metric tons of equipment and supplies for 3 astronauts on the surface of Mercury. That vehicle is depicted in Figure 7.

Unmanned Cargo-Lander Variant

An unmanned cargo-only version (analogous to the cargo-only version at Mars) would carry those 3 tons of cargo, plus essentially the entire mass of the ascent vehicle at ascent ignition (19.939 tons) as cargo: some 22.939 metric tons. That would be for the same total descent propellant load, and the same total mass at start of descent. That vehicle is depicted in Figure 8.

Conclusions

The same basic lander hardware that works from low Mars orbit can be very easily modified to work from low Mercury orbit. This is true for both manned and unmanned cargo-only configurations. This kind of “universal lander” approach can save a great deal of development effort and resources.

The modifications for Mercury are deletion of the descent vehicle heat shield and most of its aeroshell panels, and addition of extra propellants for the descent. A small allocation of propellant from the baseline ascent vehicle is also used for descent. The manned version’s cargo mass is reduced a little, and its start-of-descent mass is increased, relative to the Mars configuration. The ascent vehicle itself is unmodified. The unmanned cargo lander trades the ascent vehicle for more cargo, same total mass.

Future Efforts Contemplated

Since the moon is both airless, and lower gravity, the same components useful at Mercury should be useful from low lunar orbit, at greatly-increased cargo loads. That analysis needs to be done. There is also the possibility of flying to the lunar surface from low Earth orbit with versions of these vehicles.

Essentially the same vehicle configurations that work for Mercury and the moon should work for the four large airless moons of Jupiter, and the four largest asteroids. Those analyses need to be done.

Retaining the heat shield and aeroshell, and adding parachutes, should work for Titan, which has a dense atmosphere, but very weak gravity. That analysis needs to be done.

References

1. G. W. Johnson, “Manned Chemical Lander Revisit”, posted 8-28-12 at http://exrocketman.blogspot.com

2. G. W. Johnson, “Gravity Data on All The Interesting Worlds”, posted 7-14-12 at http://exrocketman.blogspot.com



Figure 1 – Basic Data for Destinations, Including Mercury


Figure 2 – Circular Orbit Speeds and Data for Destinations, Including Mercury


Figure 3 – Estimated Actual Velocity Requirements, Including Mercury


Figure 4 – Ascent Vehicle Data for Mars


Figure 5 – Descent Vehicle Data for Mars


Figure 6 – Ascent Vehicle Data for Mercury


Figure 7 – Descent Vehicle Reconfigured for Mercury


Figure 8 – Unmanned Cargo-Only Variant of the Descent Vehicle for Mercury