Talk:Luna-Mars Trade

All of the processes necessary for Luna-Mars trade are not sketched in any great detail, but it seems worth considering. If a mass accelerator can boost the supersonic landing Mars to low Mars orbit vehicle mentioned up to 1025 meters per second, then 49% of the take-off weight gets to orbit.--FARTHERRED11:28pm Central Standard Time 31 October 2008

Does the original creator realize that by inserting a slash in the article name, he has created a sub-article of Luna? - Jarogers2001 07:09, 1 November 2008 (UTC)

Problems like that can be avoided if we disable subpages for mainspace articles. I believe Wikipedia has done this. However, it might be a better idea for Lunarpedia if we keep subpages for mainspace articles. In that case, I suggest moving the content to "Luna-Mars trade". T.Neo 07:41, 1 November 2008 (UTC)

Moving it was my thought as well. I rather like subpages. Any objections to a move? - Jarogers2001 16:14, 1 November 2008 (UTC)

• Aw shucks. It says right here on my Wiki Reference Card not to use slash, plus sign, number sign, or any of a number of kinds of brackets in a title. I did not have the reference card with me at a distant location but probably would not have consulted it anyway. This is one way to learn. I hope it is not too much trouble to move the article.--Farred 16:36, 1 November 2008 (UTC)

It can be moved just like any other article. There is no additional procedure. - Jarogers2001 03:53, 2 November 2008 (UTC)

If we disable it, we should also disable it for the seldom used GFDL namespace and the never used CC_Luna namespace, as they have teh same function as the main namespace, just not public domain. -- Strangelv 18:18, 1 November 2008 (UTC)

I see no reason to disable it at this time. I intend to use sub-articles in the future. - Jarogers2001 03:53, 2 November 2008 (UTC)

• Why should a Mars to low Mars orbit vehicle have wings and land supersonic? The wings should allow the vehicle to kill its orbital velocity through aerodynamic drag when returning to Mars and lift from the wings should allow the vehicle to set down gently on a runway. The orbital speed being considered is only about 40% faster than the SR-71 flew, and the Mars to low Mars orbit vehicle would only move through the atmosphere at that speed for a short time while reentering from orbit. If the SR-71 could tolerate 2450 meters per second for thousands of miles of flight, a Mars to low Mars orbit vehicle should be able to tolerate flying at 3440 meters per second through Mars' upper atmosphere for a few minutes. The vehicle would not move at orbital velocity when touching down on a runway, but it would still need to be supersonic to generate enough lift for a gentle landing.--Farred 02:47, 4 November 2008 (UTC)

A lifting reentry for martian cargo is an interesting idea. I have always contemplated capsule type landings. However, I am a bit skeptical about a supersonic landing. If I am correct, supersonic on Mars is faster then on Earth due to thinner air. And, even in the thinner air, any landing gear being deployed would have to resist this force. Add to that what the gear would encounter on contect with the ground, and I don't see a happy landing. To lower the landing speed, one would have to increase the lifting force. Maybe swing wings would work, they will incease compexity.

How is the shuttle launched from the Martian surface? Is it a vertical or horizontal launch? T.Neo 07:53, 4 November 2008 (UTC)

• In the case of the speed of sound T.Neo's memory serves falsely. The speed of sound is dependent directly on the temperature and inversely on molecular weight, but it is nearly independent of pressure. The suggested shuttle would take off vertically for the version that puts 36% of take-off weight into orbit. It would be thrown into the atmosphere near the peak of mount Olympus at 1025 meters per second in the version to be boosted by electric acceleration which is suggested to achieve 49% of take-off weight to orbit. SSTO is a less demanding challenge for Mars than for Earth. --Farred 14:42, 5 November 2008 (UTC)

Woa. I thought that the speed at which sound propagates is dependent upon the density of the medium, not the temperature. - Jarogers2001 19:00, 5 November 2008 (UTC)

SSTO is definatly much easier on Mars then on Earth. What is the speed of sound on Mars? What would the landing speed for the shuttle be? WHat kind of forces would the landing gear endure? What would the heat sheild of such a craft be made of? T.Neo 16:07, 5 November 2008 (UTC)

• I will return to the speed of sound on Mars later. For now I was thinking of a titanium steel Aerodynamic shell with heat soak on reentry and an insulated internal compartment for electronics with evaporative cooling using dry ice. Landing gear would be skids with an expendable layer.--Farred 16:29, 5 November 2008 (UTC)
• The speed of sound on mars at about 0 C is about 240 m/sec making the low orbit velocity about mach 14.2 and and the contemplated electricly accelerated boost about mach 4.2 --Farred 19:22, 5 November 2008 (UTC)
• I can see how Jarogers2001 might think that the speed of sound is dependent on density since sound travles faster in steel and in water than in air at room temperature. However, we are talking about just the atmosphere of Mars here, so the speed of sound is the square root of the quantity of the specific heat ratio times the gas constant times the temperature devided by the molecular weight quantity closed. That can be rewritten as a function of density, but that would seem an unneeded complication.--Farred 20:08, 5 November 2008 (UTC)

Titanium-steel thermal soak confuses me. Thermal soak is when an insulating substance keeps heat away from the airframe. Titanium-steel seems more like a radiative heatshield, where excess heat is radiated away, like the shuttle RCC. However, the problem with the shuttle RCC (And, presumably Titanium-steel) is that they are as good at conducting heat as they are radiating it. This means that the Titanium-steel will conduct heat to the rest of the ship. Not only does the computer need to be cooled, but systems to deploy the landing gear, the RCS, the MEs, etc. Add to that, whatever payload you are carrying might not like being heated up too much. Since the methane (and LOX) tanks take up a lot of space, it might be better to make the upper hull out of thinner material, possibly aluminium.

Considering where this craft would be working, and the stresses it endures on the way down, it would have to be pretty robust. It needs a minimal use of electronics, and must be maintainable with substances found on Mars. Nothing like the current space shuttle. Think of an aircraft operating out of the Siberian tundra. It must be very robust, like many russian aircraft. T.Neo 20:43, 5 November 2008 (UTC)

• Sorry about “titanium steel.” That shows that I am not very familiar with titanium alloys. Try Grade 6 titanium alloy, containing 5% Aluminum and 2.5% Tin. Perhaps Grade 5 or Grade 9 would be better. I do not feel capable of making a final determination of alloy, but it isn’t going to be simple aluminum. It seems that I have heard of some heat resistant aluminum based alloys, but I can not name a good candidate at the moment.
• As far as cargo heating is concerned, this thing takes cargo up for shipping exports. It comes down empty. That is when the heat threat is a worry. The landing skids are constantly deployed. They are part of the airframe, like ventral fins. The flaps are operated by heat resistant cables. The control motors are in the same insulated box as the electronics. A section of the air frame with the cross section reducing from fore to aft will not have such serious heat threat problems. The reaction control nozzles can stick out there. Any unused reaction control fuel can be dumped once the flaps bite. What are “MEs?”
• I am not familiar with what you mean by heat soak, but the vehicle I describe would just soak up the heat and get hot. The idea is that the exposure to maximum heat threat will be short enough that it will not melt.
• Minimizing the use of electronics would not make the craft more rugged. Electronic components can keep going for decades. Electronics are light enough that spare boards can be shipped with the craft without significant extra expense. Anything that fails can be swapped out. That is Siberia level maintenance. The electronics are necessary for this thing to work.
• Since I am not an aeronautical engineer, I put only limited faith in my own suggestion, but nothing written here so far seems like a serious objection. --Farred 22:15, 5 November 2008 (UTC)
• I can only roughly guess what speed would be necessary for landing. I guess 1000 miles per hour. That is about mach1.9 on Mars. There is reason for thinking the thermal threat will not be too great. Besides there being only 20% of the energy per pound of reentering spacecraft as there is on Earth, the carbon dioxide atmosphere heats up to a lower temperature for any given amount of heat it absorbs because carbon dioxide is triatomic. Also since carbon dioxide is half again as heavy as the average air molecule, for any given temperature the average carbon dioxide molecule is moving only about 82% as fast as an average air molecule at that temperature. This means that carbon dioxide does not transfer heat as effectively to the skin of a supersonic aircraft as air does. The point of my greatest uncertainty is whether or not the craft can maintain orientational control while supersonic in ground effect. This is an almost completely untested area.

Pity it only takes cargo on the way up. If I wanted to export anything from the martian system it would probably be mined from Deimos or Phobos. Landing large cargo on Mars is very tricky. Plans like Mars direct and Mars for less neglect landing. The Mars Science Laboratory will land with A "skycrane" system. However, this may not hold up well to sustainability. Is there any way this could be reconfigured for payload delivery to the Martian surface? Modularity is a good idea. Anything that cannot be made on Mars should be brought from Earth. For example, the MEs (Main Engines, sorry.) will be quite complex. If one breaks, a new one could be delivered from Earth, and just "dropped in". Same with electronics.

What would the maintainance effort? And what about turnaround time? T.Neo 08:57, 6 November 2008 (UTC)

• The supersonic landing Mars to low Mars orbit shuttle (MTLMOS) concept is just that, a concept. Taking cargo down to Mars would increase the mass of the shuttle and therefore the thermal threat, but I can not produce the numbers that would say that this is possible or that it is not. Just working out the shape of the supersonic airframe, its center of gravity, and control parameters would be quite a task. If someone does that, they might say, “Yeah, we can take a little cargo on the downward leg.” They might say, “We tried but we just can not make it work. It always goes wild on the runway before touchdown and tumbles itself to death.”
• The Space Shuttle Main Engines are notorious for requiring much maintenance between flights, but sadly the over all system is even worse. I would say that if the MTLMOS can not be turned around is less than a week, it should probably not be built. I have faith that handily operable to orbit systems will one day be realized, but that faith does not allow me to answer detailed questions about how they will work. --FARTHERRED11:10 Central Standard Time 6 November 2008

It makes sense to me that this article be shared between Marspedia and Lunarpedia rather than having two separate articles. I have mirrored it onto Marspedia, and plan on adding more content soon. Let me know if this is a bad idea, I am newer to Lunarpedia than Marspedia. --Laertes 01:05, 7 January 2009 (UTC)

Thanks Laertes,--Farred 21:11, 7 January 2009 (UTC)

• The edit by Laertes at 00:38 on 8January2009 moved the description of volatiles on Phobos from a possibility to a declaration. It seems likely that this was inadvertant. If Laertes wants this to be a definite statement there should be a reference to indicate how we know Phobos is rich in volatiles.--Farred 22:41, 9 January 2009 (UTC)

Yeah, I missed that. It is fixed now, plus a reference. Thanks for the help.--Laertes 00:38, 10 January 2009 (UTC)