New Mars Forums

From AIAA’s “Daily Launch” for 6 May 2024

SPACE

Long ago, a lake on Mars might have been sprawling with microbes

The Curiosity Mars rover has detected intriguing chemical evidence, in the form of anomalous amounts of manganese oxide, which points to Mars having had not only a habitable environment billions of years ago, but also one possibly inhabited by microbes.

Title leads to Space.com,  for full article

Gist:  excess mag oxide concentration found in lake sediments similar to deposits on Earth that require oxygen in the water.  On Earth,  that oxygen comes from life. 

GW

I do want to thank Tom and Brian for the help. We got cut off when the session timed out. I tried looking for a follow-on session,  but such was not available.  I would NEVER have known the links in the text were not the real links! 

EDIT UPDATE 5-6-2024:  turns out the links I copied actually do work!  I also put them in an "exrocketman" blog site posting where "validation" is not an issue,  and they work just fine,  even when I am not signed in.  I tested them.

I just want to make clear who and what I am.  I would absolutely NEVER have guessed that an icon looking like a compass on my iphone would have been a link to a browser.  Nowhere,  not anything in my 73 years of life,  would have told me what that icon meant,  and the iphone people certainly did not!  And THAT is my gripe:  nobody ever does decent user manual documentation any more!  What I don't comprehend,  I must inevitably ignore or avoid,  or both.  And THAT explains why I cannot cope with modern technology. 

THAT is the fundamental difference between me and the people who program these phones and internet things.  I do NOT think in icons,  not at all! 

I've been pissed off at Microsoft ever since they invented Windows.  Why?  Because what do I need icons for,  when I already have words,  which stand for the tangible things that I do understand?  I quite literally think in words and things (tangible objects).  THOSE are the only thought processes that I understand AT ALL!  And that situation is very,  very unlikely to change.

When Windows came out,  I resisted it as long as I could,  for that very same reason.  I kept my machine as a DOS machine as long as possible,  using a shell program from the Germans that let me do do point-and-click with a mouse on literal words:  file names.  I saw no point to using icons,  and to this very day,  I still do not!  What is the point of learning all these other pictogram languages,  when you already have a perfectly good language based on an alphabet? 

I understand forces,  masses,  heat transfers,  fluid flow (at ANY speed),  and thermodynamics (to include rudimentary chemistry).  Those mean I understand the statics and dynamics of all sorts of moving and flying vehicles,  and what it takes to survive when you push those motions to extremes.  It also means that I understand all sorts of heat engines,  AND their limitations.  I even understand the creation and transmission of thermal,  visible,  and radar radiations,  but nothing beyond that.  It does NOT mean I understand (or am even conversant with) particle physics or especially quantum mechanics.  I know the names of those notions,  but very little more. 

I learned enough about electricity to wire my shop correctly in the school of hard knocks,  but I do NOT understand modern 21st century electronics!  Not even late 20th century electronics!  I know what a transistor is and does,  but I come from the vacuum tube days: "a transistor does what a triode tube does".  Computer chips?  Forget it! 

I knew a lot about "scientific programming" in Fortran II and IV,  and in BASIC,  but NO OTHER LANGUAGES (none at all)!!  I NEVER understood what we then called "job control language" (or "JCL"),  which was really how to interface with a computer to get it to run your program in Fortran or BASIC.  Or your software code that you purchased. 

I did have to learn a lot of math to be able to do what I could do.  After my defense career involuntarily ended,  I was able to take advantage of that,  to teach math (and engineering,  and physics) to others.  As for learning how to teach,  that came from teaching young engineers one-on-one on the job in an explosives plant.  Not just to survive,  but to thrive.  No one ever got hurt on my watch!

Most of what they tried to teach me in the education courses leading to a public school teaching certificate was just totally BS.  Plain and simple! 

With math and science,  you simply show them what has to be done,  then you show them the best known ways to do it,  then you provide multiple opportunities to try it out for themselves,  BEFORE they have to prove they can do it for a grade (and that's the mistake so often made).  Then (and only then) do you test them for the grade.  Simple as that,  and just as far from "traditional" ways and means of teaching math (or physics,  or engineering) as you might imagine.  Those subjects are objective,  not subjective.  Interpretations have NOTHING to do with it.  I cannot speak as to the other subjects.

GW

Remember:  building any sort of railroad implies the emplacement of significant infrastructure,  that being whatever kind of track your system uses.  Grading a dirt road for rubber-tired "trains" is the minimum infrastructure emplacement requirement,  although you must pay for higher rolling friction. Up-front costs vs cost-per-trip for each trip. 

My contention/opinion:  on another world with no supporting infrastructure except what we bring,  emplacing transportation infrastructure is going to be very (perhaps catastrophically) difficult,  expensive,  and time-consuming. Plus,  until you are there,  how will you know where it is that you want to put your transportation infrastructure? 

GW

There were 2 things going here.  First,  some young whippersnappers believed computer predictions and told NASA managers the no-hex Avcoat heat shield would work,  without it ever having been actually flown.  Only arc jet tests,  and if the arc only hits square on,  you won't see the scrubbing action that causes this.  (Anybody who had ever actually done anything would know better:  test data ALWAYS trumps computer predictions,  but old hands are no longer kept on staff.)

NASA managers jumped at the chance to shorten schedule and lower cost.  Even after killing 2 shuttle crews by valuing cost and schedule far above safety of lives,  they still have NOT learned the lesson not to do space flight that way.  So they installed the no-hex heat shields one-after-the-other on Artemis 1 (second flight of Orion) and 2 (third flight of Orion and first one with a crew),  expecting it to work just as well as the Apollo-style Avcoat gunned into hex cells that flew on the first Orion flight. 

It didn't work.  Now they have an Orion with a defective heat shield design,  and a looming manned flight.  They want their whippersnappers to find a way past this corner they painted themselves into,  but such does NOT exist.  The last thing they want to do is publicly admit they were wrong,  and that their mistake has cost both money and schedule time (to take the bad heat shield off of Artemis-2(3rd Orion),  build the right one,  and install it,  before risking a crew in it. They would rather risk the crew's lives,  and they want the whippersnappers to "justify" that.  But they can't,  and the inspector general report confirms that,  so the NASA managers bad-mouth that report.

This is the same arrogant-and-ignorant management BS that killed 2 shuttle crews,  and likely played a role in the deficient Apollo design that killed the Apollo-1 crew. Management culture at NASA quite clearly did not learn a thing from either the Challenger inquiry or the Columbia inquiry,  despite being publicly exposed during the Challenger inquiry for attempting a cover-up to deflect blame for bad decisions.

The time and money trying to justify this bad decision to risk a crew's lives instead of fixing a fixable problem could have been better spent just fixing the problem.  There has got to be a way to automate (at least partly) the process of gunning Avcoat into 380,000 hex cells on an Orion heat shield.  But nobody at NASA seems to have thought about that. 

The same arrogant/ignorant management style that values money over lives infected Boeing,  too,  after it took over McDonnell-Douglas.  And we have all seen where that led recently.

GW

This is ISS at the moon,  with all the extra transport costs of going to the moon instead of LEO.  A huge expense that takes away from other worthy missions. That's complaint 1.

Complaint 2:  there's no radiation shielding built into this thing capable of resisting a solar flare event similar to the 1972 event between Apollo 16 and Apollo 17.  Sooner or later,  they will kill a crew with this thing.

Complaint 3:  there's still no spin,  when pretty much everybody outside of NASA management understands that artificial gravity will be required for long-term missions.

GW

What Tom posted for me in post 287 just above is a revised version of my entry spreadsheet that embodies the 1953-vintage by-hand analysis of H. Julian Allen,  used for warhead entry back then.  I've had a version of this spreadsheet for some years now,  and it is part of the multiple lessons in the "orbits+" course series.  What I have done is clean it up of extraneous stuff not used,  add a worksheet set up for Venus entry,  and I added a model for plasma radiation heating at the stagnation location (which I validated against Apollo experiences).

This is a cleaner-looking,  and more complete version.  It does radiation heating in addition to convective heating,  something not needed in the 1950's with warhead entry.  There is the Excel spreadsheet file with worksheets for each of 4 worlds,  plus a pdf document that is a user's manual,  written to be very detailed and complete.  Both of these are better than the original versions.  I also created a set of powerpoint slides that is also a sort of user's manual.  Those are the 3 things Tom posted for us.

The new spreadsheet file actually has 6 worksheets in it.  The 4 "operational" ones for general use are named "Earth",  "Mars",  "Titan",  and "Venus",  each being set up with that world's atmosphere model from the Justus and Braun paper on entry,  descent,  and landing.  All you need to analyze an entry are the entry conditions (speed and angle-below-horizontal),  and the object characteristics (ballistic coefficient and effective nose radius).  You do need to adjust the altitudes in the list (1) to get a denser point spread where things are changing rapidly,  and (2) to make the final altitude in the list the one where speed is at local Mach 3,  where it is no longer hypersonic (each worksheet has a recommended value listed on it). Plots are generated automatically,  but un-annotated.

The other two spreadsheets are copies of the "Earth" model in which I analyzed Apollo coming back from LEO versus Apollo coming back from the moon,  in order to "calibrate" the plasma radiation model to match Apollo experiences.  I left them in place so all could see how good a match was achieved.  But,  if one wants to delete them as redundant,  that's OK. From LEO,  radiation heating was negligible,  while it dominates coming back from the moon at just under escape speed.  The model predicts just under the nominal 11 gees coming back from the moon,  which is just about right.

I would encourage any forums user to download these items and try them out.  In particular,  the user's manual document shows exactly how I copy the plots to a "Paintbrush" png file and annotate them for clarity.  It makes a really good presentation of the results. Earth,  Titan,  and Venus pretty much come out of hypersonics at high altitudes.  It is Mars where you come out low,  because of the thin atmosphere.  Which in turn makes it very sensitive to ballistic coefficient (higher coefficient is very close to the surface indeed).  But all these entries (except Titan) must take place at shallow angles,  or else the deceleration gees and heating get too high.

GW

NASA is rethinking what to do with Artemis 3 because it has no credible lander candidates for going to the moon's surface anytime soon.  Not from SpaceX,  not from Blue Origin.  Nothing yet flying except highly-experimentally. 

As for Starship payload capacity,  it is way too premature to be drawing any conclusions about that.  These prototypes being tested (and all of them lost so far) bear little resemblance to what the final product will be,  once the thing becomes successful (if it does). 

I don't know why Blue Origin's lander is not flying experimentally yet. 

I do know why Starship is not ready yet:  (1) the job is bigger and more difficult than they first thought,  requiring more tests and more time to "get it right",  and (2) delays getting licenses to fly early on lengthened the time considerably,  because Musk acted like an idiot and had SpaceX violate the terms of its licenses.  Shotwell makes good technical decisions,  Musk has a history of making bad ones.  They would be bankrupt and out of business without her and the staff she has.

GW

Variants of the same A-7 suit were used on the X-15,  Mercury,  Apollo,  Gemini,  and Skylab.  Baseline pressure was 3.7 psia,  but it could have been less.  Not a lot less,  but 3.0 psia works.

There is a rule-of-thumb for determining whether you have to do pre-breathing to blow off nitrogen before being suited up at lower pressure in a pure-O2 suit.  The partial pressure of nitrogen in the two-gas atmosphere you are breathing,  divided by 1.2,  is the min pure-O2 suit pressure you can use without doing pre-breathing.  You can use higher without pre-breathe,  but not lower.  For synthetic air at 14.7 psia,  20.94% oxygen,  the nitrogen partial pressure is 11.62 psia (O2 is 3.08 psia).  11.62/1.2 = 9.68 psia,  which would be the min piure-O2 suit pressure for no pre-breathe.  See the problem? 

There's both short-term and long-term health issues for low O2 partial pressures,  or low atmosphere pressures at Earthly air composition.  Short term,  the oxygen mask limit is the pure O2 pressure at about 45,000 feet,  or maybe only 40,000 feet.  Above that for more than several seconds,  fighter pilots have to wear some sort of pressure suit so they can do pressure breathing,  and still have the cognition to function as pilots.  40 kft is 2.73 psia atm pressure,  which within a vented O2 mask is the O2 pressure corresponding to a suit.  At 45 kft this is 2.15 psia.  Which is exactly why a pure O2 pressure suit can be lot lot lower than 3.7 psia.

There is another limit on that short-term scenario:  loss of moisture from the lungs,  causing excessive drying of tissues,  risking cracking and bleeding.  That happens after some hours of exposure,  and is not much of a problem if the pure O2 pressure is 3.0 psia.  Which is where my min acceptable suit value comes from for an all-day EVA-type activity.

Long-term,  the experiences with long-term hypoxia and long-term childbirth difficulties show up at about 9000 feet elevation.  No higher than that,  routine health is all the same,  more or less independent of elevation.  Above that (and people do live above that),  chronic hypoxia indications increase sharply with elevation,  particularly above 13,000 feet.  And complications of childbirth increase in frequency rather noticeably with altitude.  At 9000 feet,  pressure is 10.51 psia,  and the partial pressure of O2 is 2.20 psia (that of N2 is 8.31 psia).  You pretty much must have a partial pressure of O2 at or larger than 2.20 psia in any two-gas habitat atmosphere,  for long-term health. 

There is another danger,  when one uses lower-pressure habitat atmospheres enriched in O2:  enhanced fire danger.  In sea level Earthly air at 14.70 psia and 70 F,  the mass concentration of oxygen measures 0.275 kg/cu.m.  For an Arrhenius reaction rate model as an indication of fire spread rapidity,  rate ~ [Cf^n + Co2^(1-n)]exponential T-factor.  n is usually in the vicinity of 1,  so n-1 is also in the vicinity of 1.  You basically have the same threat or less from fire spread rates as we experience here on Earth,  if your oxygen concentration is at or below that 0.275 kg/cu.m figure.

You also have to worry about leak-down effects.  10% pressure drop is the usual rule-of-thumb for suits.  And presumably habitats.

Here is what I get for 0.45 atm 32-gas in the habitat at 45% O2 and 55% N2:  Pp O2 = 2.976 psia + Pp N2 = 3.637 psia = Ptot = 6.613 psia.  Leaked down 10% but maintaining the 45-55% composition,  that is 2.645 psia O2 + 3.233 psia N2 = 5.878 psia total.  The design hab corresponds to a min 3.0321 psia pure O2 suit for no pre-breathe,  and a 0.257 kg/cu.m O2 concentration. 

Even leaked down,  the 2.645 psia O2 meets the 2.200 psia O2 long-term exposure criterion,  the 3.03 psia suit allows far easier MCP designs,  and the 0.257 kg/cu.m means the fire risks are a tad less severe than a sea level 70 F day on Earth.  The 3.03 psia suit is way better than vented O2 masks at 40-or-45 kft,  and there's no pre-breathe requirement down to that 3.03 psia suit pressure level.  How can you lose?

GW

0.01 REM/day*365 days/year = 3.65 REM accumulated (slowly) in one year,  compared to the old safety limit of 50 REM in one year.  OK.

0.01 REM/day*30 days/month = 0.3 REM accumulated slowly in 1 month.  Compare to the old safety limit of 25 REM in one month.  OK.

0.01 REM/day*365 day/yr*10 years = 36.5 REM accumulated over a career 10 years long.  Compare that to the old career safety limit of something in neighborhood of 300-400 REM accumulated over the entire career,  which varied with age and gender.   Looks OK to me.

I know they recently lowered the limits,  but only a little bit. 

GW

Yes,  I know.  I have seen it.

I was there 2nd half of winter 95-96 and for winter 96-97,  which were both 100-year record-setting winters for cold and snow,  even by Minnesota standards.  That was a real education for a Texas flatland boy. 

We moved in between Christmas 95 and New Year 96,  during a local heat wave.  It was 17 F.  Then it dropped below 0 and stayed there.  From New Years' Day to mid-March,  there was not one single day when it was not at least 20 below 0 F for the morning low,  and never got above 0 F for the afternoon high. 

That stretch finally broke mid-March,  when the wind died and the sun came out.  It felt warm.  We were all running around the snowbanks outside in short sleeves,  myself included.  Because it felt warm.  The actual temperature turned out to be positive 3 F.

The worst day was Feb 2,  1996,  in Mankato,  MN.  It had been -30 F all night with 40-knot winds.  It was -31 F in Mankato that morning,  with an afternoon high of -14 F.  Up in the arrowhead region near the Canadian border,  it was -61 F (not a wind chill).  200 miles further NW at Winnipeg,  it was -84 F,  again not a wind chill.

The next winter was not quite as cold,  but even snowier.  About 10 miles west of me,  the snowpack was 20-30 feet deep all the way to Montana.  I thought my thermometer was broken,  because it said -10 F every morning from November to March.  I found out it was not broken when we moved back to Texas,  and it went to 104 F.  I had 2-to-5 feet of snow in my yard all winter long.  The meltdown was only 2 weeks long,  in mid-April,  which caused massive flooding in multiple states.

GW

Interesting idea.  I take it Callisto is outside Jupiter's radiation belts.

GW

I just did the best I could,  with my very limited understanding of all this internet/computer stuff. 

The recent posts now show numbers of views.  The old one about the Lionel train has 1300 views now,  but it's been up there for many years.  My son put it there. 

For me,  it's monkey-see,  monkey-do.  And the funny part is that I really do like bananas. 

GW