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Posted on 04/24/2007 8:09:35 AM PDT by SunkenCiv
A moderately massive early Sun has been proposed to resolve the so-called faint early Sun paradox. We calculate the time-evolution of the solar mass that would be required by this hypothesis, using a simple parametrized energy-balance model for Earth's climate. Our calculations show that the solar mass loss rate would need to have been 2-3 orders of magnitude higher than present for a time on the order of ~2 Gy. Such a mass loss history is significantly at variance (both in timescale and in the magnitude of the mass loss rates) with that inferred from astronomical observations of mass loss in younger solar analogues. While suggestive, the astronomical data cannot completely rule out the possibility that the Sun had the required mass loss history; therefore, we also examine the effects of the hypothetical historical solar mass loss on orbital dynamics in the solar system, with a view to identifying additional tests of the hypothesis. Planetary and satellite orbits provide a few tests, but these are weak or non-unique.
(Excerpt) Read more at arXiv.org ...
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a climate topic, of sorts, perhaps pingworthy.
It’s warming Mars too. The polar ice caps are melting there.
And there seems to be warming on Pluto.
That George Bush is just too darn dangerous!
Okay...here’s a follow up to that. One idea about how to make Mars habitable is to melt the ice caps, thereby freeing CO2 and H2O into the atmosphere. This would cause a runaway greenhouse effect freeing more CO2 from the regolith. This would in effect raise Mars’ atmospheric pressure to something that we could reasonably work in in a shirt-sleeve environment, except with breathing masks/air tanks. If the ice caps melt, with this process start?
Okay...here’s a follow up to that. One idea about how to make Mars habitable is to melt the ice caps, thereby freeing CO2 and H2O into the atmosphere. This would cause a runaway greenhouse effect freeing more CO2 from the regolith. This would in effect raise Mars’ atmospheric pressure to something that we could reasonably work in in a shirt-sleeve environment, except with breathing masks/air tanks. If the ice caps melt, with this process start?No. Due to its lower density and smaller diameter, Mars has little atmosphere (surface pressure is about what the pressure is above Earth at 40 miles altitude; space is defined as 50 miles). The way to work in a shirtsleeve environment on Mars is to deploy inflatable plastic domes (like a plastic bag greenhouse), and carry repair kits to deal with the tiny pebbles of space debris which hit Mars on a regular basis.
I’ve heard an interesting proposal in this regard by Richard P. Speck of Micro-Space Inc. Now it does seem a little crazy, but he proposes sending a “camping” expedition to Mars, where the day-to-day operations would be carried out in a portable inflatable tent, now supplies would have to be landed, and I think he proposes a single site “depot” that you would enter, pick up your box of supplies, and go out to the tent. I propose a “dog sled” type mission along the same vain. Although I don’t know how you would reconcile that with being able to anytime abort to orbit...
The success of the little rovers suggests to me (it’s around here on FR somewhere) that a big winnebago kind of thing would make an excellent station. It could be sent crewless, landed, and checked out remotely from Earth, and then double-checked by the crew arriving in Mars orbit sometime thereafter. The third component (also sent crewless) would be the de-/re-orbit vehicle. The second component (the one with the crew) would have everything needed to go, enter orbit, leave orbit, and return to Earth (to maximize safety).
The surface habitat would be mobile, to maximize convenience, and as you said, to provide a shirtsleeve environment. It would be photovoltaic powered, with some kind of fuel cell backup. The big bubbles and the like could arrive later (and whenever, and wherever) and self-deploy, or the crew could do the needed work during EVA.
The winnebago (the “Ares-stream” might be more appropriate) would last for years, and crews could come and go. It would be left on the surface, and the access to and from the surface would be via that third component. I wonder about reuseability of the de-/re-orbit vehicle (perhaps it could be built to require only refueling).
:’)
Note: this topic is from 4/24/2007.
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