Talk:The Lunar Transverse Maps - Revision history

Jriley: New section: Student capabilities and Slope

2008-03-31T22:50:16Z

New section: Student capabilities and Slope

Jriley: New section: Thermo and other spacecraft

2008-03-31T22:44:26Z

New section: Thermo and other spacecraft

Jriley: Opertunity knocks

2008-03-29T13:15:50Z

Opertunity knocks

New page

The new lunar data looks like a once-in-a-lifetime oppertunity to get large number of students directly involved in lunar exploration.

--[[User:Jriley|Jriley]] 13:15, 29 March 2008 (UTC)

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		+
		+	== Student capabilities and Slope ==
		+
		+	Dear Lunarpedia people,
		+
		+	The Lunar Transverse Maps idea makes several assumptions that
		+	I feel are needed for a student rover to have any possibility of
		+	success, but that are not needed for a well funded project:
		+
		+	1. Lunar thermodynamics is a killer. It is much worst than
		+	Mars. Students do not have a good understanding of thermo in general
		+	and do not have the complex models needed to design reliable
		+	spacecraft.
		+
		+	2. The student rover electronics will only survive -10C to
		+	+40C. Outside that range it will die. The batteries and motors will
		+	die too. Student level projects like the X-Prize simply do not have
		+	the hundreds of millions of dollars to develop better than
		+	off-the-shelf devices and materials.
		+
		+	There are sweet spots on the Moon where the temperature is
		+	moderate and the students must go after them. Hence the two suggested
		+	approaches.
		+
		+	----
		+
		+	Slope is the second key. The surface is loose pulverized rock
		+	and the gravity is weak. It is very difficult to get the traction
		+	needed to go up a steep slope or even control the rover coming down
		+	one. The Apollo rover limit of 25 degrees (about 2.2 run to 1.0
		+	raise) is going to be hard to beat. Even treaded vehicles do not work
		+	much better in the low gravity. Two area on the Moon that are not
		+	connected by a genital slope are simply not connected. The idea of
		+	circling the Moon at any latitude within this slope limit is a long
		+	shot at best.
		+
		+	The present slope data is simply not good enough to even
		+	understand the extend of this problem. I think the LRO altimeter will
		+	be the first data set up to this job. We need to get people to work
		+	on it right away.
		+
		+	Any ideas you have for promoting this idea are most
		+	appreciated. The only contacts I have at NASA and they are in a
		+	frugal mode at the moment. Ed Out is definitely in their mandate, it
		+	is just that it rarely gets independent funding and then only the most conservative
		+	idea. There is a lot of climate change going on of late, but I do not
		+	think that means that hell is going to freeze over any time soon.
		+
		+	Thanks again for your interest.
		+
		+	--[[User:Jriley\|Jriley]] 22:50, 31 March 2008 (UTC)
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	--[[User:Jriley\|Jriley]] 13:15, 29 March 2008 (UTC)		--[[User:Jriley\|Jriley]] 13:15, 29 March 2008 (UTC)
		+
		+	----
		+
		+	== Thermo and other spacecraft ==
		+
		+	Dear Peter,
		+
		+	Spacecraft must get rid of internal heat to keep their
		+	electronics from overheating. This is done with a radiator that
		+	rejects the heat to deep space.
		+
		+	It is very easy to design a free flying spacecraft to point
		+	its solar panels at the sun and its radiator in the anti-sun
		+	direction. This works very well.
		+
		+	On the Moon you cannot do this. The surface of the Moon
		+	blocks more than 1/2 the view of the radiator and it is difficult to
		+	keep the effects of the sun completely off it. The result is like
		+	having your rover in a giant frying pan at the temperature of the
		+	local surface.
		+
		+	The Russian Lunapods did last about a month. They weighted
		+	about a ton, were the size of a Volkswagen Beetle, and had both solar
		+	and nuclear power. This is not a good comparison.
		+
		+	The Apollo rover is better. The radiator was at the back
		+	where a trunk lid would be. The astronauts arrived mid-morning when the weather was good and left three days later before it got too hot. They would have cooked to death a day or too later if they had stayed. Just as the rovers did.
		+
		+	The Apollo rover electronics had a tendency to over heat. The
		+	problem was mostly dust covering the radiator, but they also
		+	overheated if used near a sunlit mountain side.
		+
		+	The astronauts did leave some scientific instruments that ran
		+	for quite a while. Again this is a poor comparison. The instruments
		+	were simple and designed to be very heat resistant. They were also
		+	nuclear powered.
		+
		+	The electronics box will be covered with MLI (Multi-layered
		+	Insulation) except for the radiator. This is up to 12 layers of
		+	aluminized plastic with space between. It is great insulation but
		+	insulation will only do so much. If the radiator is not very
		+	effective the entire electronics box will simply reach the ambient
		+	temperature of the surrounding in a few tens of hours.
		+
		+	The two ideas suggested in my paper are 1) move away from the
		+	equator until the peak daytime temperature does not kill your
		+	electronics, or 2) bury in the regolith until the day/night
		+	temperature extremes are averaged out. Both approaches have serious
		+	problems.
		+
		+	I can provide a spreadsheet that I used to estimate the
		+	latitude of the northern and southern roads, but it does not have much
		+	text with it. I am not qualified to do a realistic thermodynamic
		+	study of the proposed rovers. It is not my field and I have not been
		+	able to get any volunteers to do it. This work would take about 100
		+	hours and a fairly large desktop computer with the correct
		+	professional software.
		+
		+	Thanks for the discussion.
		+
		+	--[[User:Jriley\|Jriley]] 22:44, 31 March 2008 (UTC)

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