New Mars Forums

Those old pictures of S-4 are priceless.  She was lost,  you know.  Collision with a ship.  They could not raise her in time to save a few survivors. 

GW

This Stoke Space vehicle is a very interesting 2-stage cargo launcher to low Earth orbit.  Their liquid-cooled metal heat shield is an interesting design,  unlike anything ever flown before.  Something similar was to have been tested aboard the X-20 "Dyna-Soar",  but that project was cancelled somewhere close to 1960 with the first prototype test vehicles coming off the assembly line at Boeing.  Memory may not serve,  but I think it had to do with USAF's manned space program being terminated in favor of NASA' civilian manned space program.  Point is,  it never flew. 

I hope this thing works.  The second stage returns like a space capsule,  heat shield first.  I rather doubt it could return without the payload shroud,  as that would expose the inner workings of the stage to the very hot gases in the separated wake behind the vehicle.  Those are not moving as fast,  but they are at the same effective temperature as the gases smashing against the heat shield. 

You have to fire the deceleration engines around the periphery during entry,  because it is one of the propellants they are using for the coolant.  That vaporizes the propellant,  and you have to do something with it. 

That technique requires a small area compared to the size of the vehicle,  which matches up well with an end-mounted shield.  I doubt it would be practical for SpaceX’s Starship,  because their lateral-surface heat shield is so very much larger compared to the vehicle size.  That would be an enormous quantity of coolant liquid required.

I've seen something somewhere else that suggests one possible application of the Stoke Space vehicle might be "refueling satellites".  Most of the things I see about that topic are aimed at delivering more xenon for the electric thrusters that maneuver such satellites.  Attitude thruster gas is another possible refueling item.

There is the possibility of using this to deliver modest quantities of real combustion rocket propellants to LEO,  in containers inside that payload shroud.  The containers could be delivered and the shroud closed back up for the return.  Or the containers could be designed for delivery of the propellant itself in zero gee.  That's easy with room temperature storables,  you just build a bladdered tank and use gas pressure to squeeze the bladder,  "extruding" the propellant out. 

There are no bladder materials that work at cryogenic temperatures,  so cryogenic propellants require "something else" for direct propellant delivery in zero gee.  I think I know how to do that without spinning or accelerating any vehicles. It's patent-pending right now.

GW

Kbd512,  some of your arguments fall apart because you believe and quote the far-right-wing lies instead of the facts.  For example:  fact --  Biden funded and shipped weapons to Ukraine.  Fact -- Trump did not.  Fact -- Biden maintained sanctions upon Russia.  Fact -- Trump did not.  As I keep telling you,  but you keep failing to understand,  I do not listen to what ANY public figures say!  I ONLY look at what they actually do!  It is easy to lie.  It is hard to conceal actions.

Void: 

I lived up there for a year and a half and got to know what kind of people Minnesotans are,  generally.  At the outset of this,  nearly all the violence was done by ICE agents violently arresting people that largely should not have been arrested.  There are some illegals,  and some who do violence,  yes,  but they are a minority.  And the very same things have been happening in other cities,  too,  including right down here,  near me,  in Waco,  Texas.  Actions speak far more truthfully than any words.

As this spectacle wore on,  the protestors got more enraged by the evils they see being committed right in front of them.  That provokes them to increasing amounts of rage and violence.  Perfectly understandable and quite predictable.  And it is actually Trump's plan to cause enough trouble with his ICE agents,  so that enough violence will erupt to justify sending active duty army troops to Minneapolis under the Insurrection Act.  Those would be to occupy and intimidate what is usually a mostly-Dem-voting opposition city.  If you scare them bad enough,  they will not risk going out to vote.  We saw that movie before,  in Nazi-occupied Europe,  and in the Bolshevik takeover of Russia.

This stuff in Minneapolis is NOT about illegal immigrants at all!  This is about using ICE as a secret police force and as an agitation agent to justify occupying an American city (and maybe an American state) with regular army troops,  so that resistance to the dictatorship Trump is imposing will be less.  (And he is a traitor of the aid and comfort type,  on at least two counts,  by the way.)

You may be half an hour from downtown Minneapolis,  but you are not safe there.  And it would appear to me that you do not even recognize the danger.  You do seem to quote far-right wing lies about some things.

GW

And by the way,  either Putin will succeed against Ukraine,  or this thing will continue to drag on.  Either way,  it will look like to Xi in China that the US and Europe and our Pacific allies will not effectively oppose him invading Taiwan and annexing the South China Sea.  Indeed,  the longer Ukraine has dragged on,  the more aggressive the moves Xi's China has been making in that region.  Once he does move WW3 starts in the Pacific.  If Putin "wins" anything over Ukraine,  he will start WW3 in Europe.

THAT is what we face,  in addition to a Trump dictatorship here at home!

GW

There is no rational reason for Trump wanting Greenland.  It is the territory of a NATO ally,  and we have a base or two there now.  We have had many bases there in the past.  We could easily put more bases there to project US power into the Arctic,  and forestall any Russian or Chinese advances upon Greenland.  And that could be easily done without upsetting or angering any of our allies and NATO partners.

Trump considers none of that,  he just "wants Greenland",  and is apparently willing to use military force to take it.  That would be attacking a NATO ally (Denmark) to do it,  which under Article 5,  is an attack upon all of NATO.  And THAT is why Trump using force to take Greenland is the end of NATO,  since we are supposed to be part of that treaty. 

I'll tell you what all this bluster really is:  Trump is trying anything and everything he can,  to destroy NATO for Putin.  I've seen him as a Putin lap dog ever since he ran for office the first time.  Destroying NATO is something Putin would dearly love to do,  but he cannot do it.  Nor could his Soviet predecessors. 

Russia was not an enemy under the two elected leaders before Putin,  but it is once again under Putin,  just like it was when it was the Soviet Union.  Russia is the enemy.  NATO is our friend.  Destroying NATO for the enemy (Putin's Russia) is very most definitely providing aid to the enemy,  and also inherently comfort to that same enemy. 

And THAT is one of only two definitions of TREASON under our Constitution!  Trump is trying to commit gross treason by tearing apart NATO over Greenland!  For Putin!

This is way beyond any possible politics.  This is about our country and its safety from its enemies.  The GOP majorities in the House and Senate need to get with their Dem colleagues and impeach and convict this ever-so-evident traitor in the White House,  to get him out of there ASAP!!!  And if they do not,  we-the-people should consider them complicit in Trump's treason and get rid of them,  too!

If that takes an uprising,  then so be it!

GW

The odds favor their survival,  but the lethal uncertainty is nowhere near zero.  Initially,  the excuse was eliminating the skip and just going for direct entry.  I do not see anything of that plan in the recent stories.  This reminds me eerily of Challenger and Columbia. 

I am still disappointed seeing the entire debate framed only as "fly what you have" vs "total redesign".  Total redesign is NOT required,  all they need to do is go back to the labor-intensive hand-gunned heat shield.  There is NO REDESIGN associated with that!  They already HAVE that design!  They already flew it!

Doing that would enable them to work out how to cast those tiles with the hex cores in the them,  and fly such a thing,  even as a subscale test article,  to see it actually work right.  I already showed how to do that revised processing with an extrusion press,  here on these forums,  and I already sent that idea to them via a contact I knew within NASA,  who has since retired.  I NEVER EVER heard back from their heat shield people,  to whom my contact forwarded my materials.  "Not invented here" is a real flaw shared by lots of big organizations! 

But it would definitely work,  because the fibrous nature of the charred hex helps tie the otherwise weak carbon char together.  It's a composite material that is better than just the carbon char from the polymer alone.  I know that because of my experience with ablatives in ramjets and solid rockets.  If you cannot reinforce the char,  it goes away too quickly,  in one fashion or another.  Which experience goes way beyond sample testing in an arc jet tunnel,  and running CFD codes that usually do not deserve to be believed,  without confirmation testing!  I'm talking real burn experiences with real motors and engines here!

The Artemis 1 failure already proved that fiber reinforcement contention of mine!  The only difference between Artemis 1 and the first Orion that flew was that they deleted the hex to cast the tiles instead of hand-gunning the polymer into a hex core already attached to the capsule,  like Apollo.  Which is what flew on the first Orion.  That's NOT a FULL re-design of anything,  it's only a variation on the cast tile processing they now prefer (at the risk of the crew's lives,  I might add,  if they don't do something to reinforce that char).

GW

Use the long-known NASA criterion for no pre-breathe time.  The partial pressure in the habitat,  of the nitrogen,  may not exceed the total pressure of the pure oxygen fed to the suit,  by more than a factor of 1.2. 

If you satisfy that criterion,  there is no "pre-breathe" time associated with donning an oxygen suit and going outside immediately,  without risking the bends from the nitrogen. 

If you do more than about half an atmosphere of 21% O2/ 79% N2 mix in the habitat atmosphere,  at more than around 0.5 atm hab atmosphere pressure,  this is impossible to do. 

But half or a little less than half an atmosphere of oxygen-nitrogen mix in the habitat atmosphere,  meets that criterion for donning a pure O2 suit and just going outside with no pre-breathe.

GW

Propellant manufacture is by far more hungry for high oxygen generation rates.  The equipment to do this will inherently be large,  and power-consumptive.  There is no way around that ugly little fact of life.

I rather think that electrolyzing water purified from mined ice is the better choice for propellant manufacture,  especially if the propellant is LOX-LH2.  Your biggest energy expenditure will be for liquifying the gases.  Although electrolysis might be a fairly close second,  if the ~6% efficiency typical here obtains there. 

It is possible to get LOX-LCH4 propellants by using both water and Martian CO2.  But it's neither electrolysis nor the Moxie process.  Just more big heavy,  power-consumptive machinery to do it on a big scale. 

Purifying water from likely-polluted ice is a thermal process after an initial filtering process.  Either you distill it,  or you freeze it.  Sea water freezes to fresh water ice,  enhancing the brine content in the sea water just below the ice cake.  You could run it through 2 to 4 steps of that,  and get most of the various salts out,  possibly even including the perchlorates.  But all the water you start with will reach the end as product;  there will be significant concentrated brine waste.  You can take advantage of the cold environment to do the freezing.  Distillation would work just like it does here.  You just need to supply a lot of heat energy.  And again,  not all the water you start with arrives as product.  There will always be concentrated brine waste!  It is a Second Law thing.

For the Martian CO2,  the biggest problem is compression.  Compressors there will look (and weigh) more like vacuum pumps,  a lot of power-consumptive machinery for just a very small throughput stream.  The 6 mbar atmospheric pressure is what forces that outcome.  10 mbar,  no difference.  Same problem:  the local "air" is a 1st cousin to vacuum.

If you can slightly cool some sort of duct to a temperature below about -110 F,  the CO2 will preferentially condense out first as a dry ice frost or snow in the duct.  You would have to stop and recover it out of that duct,  making this more of a batch process than any sort of continuous flow process.  Be that as it may,  pack the recovered dry ice tightly into a pressure container,  and warm it above -110 F.  It will be high-pressure CO2 gas in that container in a small amount of time,  and for very little energy input compared to direct compressor-type compression.  Once near 1+ atm pressure,  your ordinary Earthly-type compressors and other machinery will work "right".  But not until you "pre-compress" it to near 1 atm.

GW

A reminder:  the insight mission was very near a polar cap.  All the others have been at "temperate to equatorial" latitudes. 

Subsurface conditions are quite different at polar latitudes here on Earth.

At around 30 deg N latitude here in Texas,  the soil temperature about 6 feet or more down is near 58 F,  with the year-round-day0night average temperature (standard atmosphere model) 59 F.  That's 2 to 3 m down!!!

At the surface,  summer soil temperatures are near the 95-105 F daytime air temperature,  and around 80 F at night.  In the winter,  pipes buried 6 inches or more do not freeze,  if the cold snap is shorter than 2 weeks below freezing.  A foot is better insurance.  But both water systems and fire mains are buried much deeper than that.  Fire mains are 6 feet down,  by code.

GW

You will need doors and airlocks to go into and out of this structure.  Those things have to open and close.  A simple duct through the wall does not have to open and close.  That is an easier thing to do than installing doors and airlocks.  Why not take advantage of the cold heat sink outside to cause the heat you must move to flow spontaneously from warm to cold,  instead of expending power to pump it against an adverse temperature gradient?

Whatever the population is,  that sets how big this dehumidification system must be.  I do NOT have that information!  It is the water vapor in their exhalations that creates the excess humidity in the habitat atmosphere.  You want to condense that out and recover the water to reuse it.  The warm/cold loop is a way to do that with only one moving part:  an axial-flow fan,  and a very low energy cost to run it.  I'm just guessing about a 2 foot diameter duct flowing at something in the 4 to 20 foot/sec range of speed.  Very low friction loss to overcome with the fan.  We are talking a few dozen watts to run the fan.

You do not run the humid atmosphere through that loop,  that risks clogging the duct with frost.  It is a closed-loop system isolated from the atmosphere in a pressure-tight loop of simple sheet metal ducting.  The same gas mixture can be used inside the loop as in the habitation,  but it needs to be zero humidity.  The atmosphere in the habitation you want to run at about 30% relative humidity,  no lower than about 20%.  Risk of drying out nasal tissues if you go too low.

The inherent heat loss to the outside is air flow at maybe 1 to 2 lbm/sec dropping from around 77 F to no colder than 40 F.  That loss would be trivial compared to the heat loss directly through the walls of the dome,  simply because of its enormous exposed surface area.

GW

From AIAA's Daily Launch email newsletter for Wed 12-17-2025:

Space
NASA's MAVEN spacecraft is still silent at Mars — and apparently is spinning, too
NASA still hasn't heard from its MAVEN Mars orbiter, and the spacecraft appears to be spinning in an odd way as well.

-----   
My take:

Odds are the craft was struck by something:  a meteor or a piece of debris.  That event would both alter the orbit and induce a spin,  because it is extremely unlikely the axis of the strike would pass through the center of gravity.  And those literally are the two symptoms seen,  as described in the full space.com article this headline links to.

GW

When you are located in a cold place like most of Mars,  or the lunar night,  take advantage of that cold to condense the moisture out of your air.  You need only a way to collect the frost/ice to use it for water. 

GW