34 votes

Could an acid-proof, solar-powered aircraft stay aloft on the sunny side of Venus more-or-less indefinitely?

Thanks to one of the links in the comments above, I was able to discover that NASA wrote a fairly detailed 27 page report back in 2004 on their investigation of this idea. The synopsis says Solar ...
phil1008's user avatar
  • 4,348
33 votes

Why are the Martian poles not covered by dust?

Well, from these pictures, I think you can see that there is in fact a visible ice sheet at the poles, and you can see that global dust storms do in fact kick dust over the poles. Dust that blows into ...
Darth Pseudonym's user avatar
31 votes

By my calculation the cumulative mass of Mercury, plus Venus, plus Earth's moon, plus Mars, plus Mars' moons, total 99% of Earth's mass. Am I correct?

According to Wolfram Alpha, your calculation is correct. (The masses of Phobos and Deimos are negligible here.) It's not a particularly remarkable coincidence; glancing at a list of solar system ...
Russell Borogove's user avatar
25 votes

Does the atmospheric pressure of Mars fluctuate because of the seasonal evaporation of the polar ice caps?

According to https://marsed.asu.edu/mep/atmosphere The deep cold southern polar winter removes CO2 gas from the atmosphere by freezing it directly onto the south polar cap. As temperatures drop below ...
Alan Birtles's user avatar
  • 2,066
23 votes

Term for deformation due to gravity

The generic term is tidal deformation. At a distance of ~385000 km, the Moon subtly distorts the shape of the Earth. Those distortions are readily visible in the Earth's oceanic tides, and not quite ...
David Hammen's user avatar
  • 74.8k
19 votes

Term for deformation due to gravity

Could you be thinking of the Roche limit? From the link: In celestial mechanics, the Roche limit, also called Roche radius, is the distance from a celestial body within which a second celestial body,...
Erin Anne's user avatar
  • 11.3k
15 votes

By my calculation the cumulative mass of Mercury, plus Venus, plus Earth's moon, plus Mars, plus Mars' moons, total 99% of Earth's mass. Am I correct?

Russell Borogove's answer got me wondering how one might best successively approximate the mass of the Earth by using other solar system bodies (say, if you wanted to balance a scale). My every ...
Erin Anne's user avatar
  • 11.3k
7 votes

Nuking mars for colonization

Fusion bombs have existed for decades, they are called thermonuclear weapons, and are many thousands have been produced. A thermonuclear bomb uses a small fission bomb primary to cause the extreme ...
GdD's user avatar
  • 20.3k
5 votes
Accepted

Apparent diameter of a planet

Apparent diameter is inversely proportional to distance, and by trigonometry (assuming coplanar orbits), you could obtain the distance to the planet from the relative phase angle: $$d = \sqrt{(\sin(\...
SE - stop firing the good guys's user avatar
5 votes

By my calculation the cumulative mass of Mercury, plus Venus, plus Earth's moon, plus Mars, plus Mars' moons, total 99% of Earth's mass. Am I correct?

Using the gravitational parameters of JPL: DE430/431 (the most accurate I could find), the discrepancy between the cumulative sum and the mass of the Earth is about five magnitudes higher than the ...
SE - stop firing the good guys's user avatar
4 votes

What is the minimum pressure of a purely CO₂ atmosphere on Europa that can retain enough heat for surface liquid water?

A very rough starting point is how much this atmosphere would differ from a perfect blackbody. The melting point of water is roughly 270 kelvin for a wide range of pressures, so with that as a surface ...
SE - stop firing the good guys's user avatar
3 votes
Accepted

Is the crust of the Moon different on the near side and the far side?

A couple of interesting hypotheses are given for the difference in Why Do We Have a Two-Faced Moon? Both hypotheses stem from a small planet colliding with Earth - The Giant Impact Hypothesis followed ...
Fred's user avatar
  • 13.1k
3 votes

Is the crust of the Moon different on the near side and the far side?

I suspect that the exact answer is not entirely clear. The evidence is a bit thin and the event happened so long ago. That said what evidence there is suggests that a Mars sized object hit another ...
Slarty's user avatar
  • 9,333
3 votes

Nuking mars for colonization

when fusion bomb technology is proven, couldn’t we just use that to colonize mars instead No. Fusion bomb technology is already proven, but it is entirely inadequate for terraforming. or do we just ...
gerrit's user avatar
  • 11.6k
2 votes

Would a ice core samples taken on the Moon provide us with information about the past that we cannot easily obtain in other ways?

Yes. There are two broad categories of things we can learn from ice cores on the Moon: scientific and it's viability as a resource for space exploration. Scientific Here are some examples: Some of the ...
Galerita's user avatar
  • 924
2 votes

Will Enceladus run out of water due to it being lost to space?

No. The approximate escape rate of water on Enceladus to space is $\rm \dot{m}_{\rm H2O}\approx 5000\; g\;s^{-1}$ (ref, with a factor 10 uncertainty in that number). Ganymedes icy mass $\rm m_{H2O}$, ...
AtmosphericPrisonEscape's user avatar
2 votes

Does the atmospheric pressure of Mars fluctuate because of the seasonal evaporation of the polar ice caps?

More a comment to the answer above, than an answer on its own: the referenced web page provides the raw data of the diagram as a tab separated ASCII: ...
Buttonwood's user avatar
2 votes

Can waterworld exoplanets have an ocean that's fresh or brackish by terrestrial standards?

All other things being similar to Earth, your exoplanet's ocean would be almost as salty as earth's. All three of the mechanisms you list for Earth sources of salinity would still be in effect, but ...
Woody's user avatar
  • 21.6k
2 votes

Does Saturn have a solid surface?

It is worth emphasizing what was mentioned in the comments to another question - all the outer planets have atmospheres that gradually transition from gas to supercritical fluid. There is no ocean of ...
Mark Foskey's user avatar
1 vote

How can you warm up Mars?

The easiest way to warm Mars is by adding artificial greenhouse gases to the atmosphere. These would be manufactured in-situ. They could potentially trigger a runaway greenhouse effect, increasing CO2 ...
Galerita's user avatar
  • 924
1 vote

What makes materials on the Moon look so different when the sun is high?

The brightness seen in the photographs is likely due to Heiligenschein. The effect is not confined to "local noon". It is seen at the antisolar point. Because Lunar survey satellite image ...
Woody's user avatar
  • 21.6k

Only top scored, non community-wiki answers of a minimum length are eligible