Tuesday, March 03, 2009

Summer On A Dwarf Planet


Everywhere we look, the Solar System is far more complex and exotic than we expected.

Take Pluto. Back when I started reading science fiction, and getting interested in astronomy, it was believed that Pluto was a lonely, deep-frozen ball of ice where nothing much happened. Now, we know that it orbits around a common centre shared with Charon, a body about half its size, while two small dark bodies, Hydra and Nix, orbit beyond the edge of a tenuous, dusty ´╗┐system of ring arcs - a compact toy of a system, as orderly and self-contained as an orrery. And we also know that Pluto has a thin atmosphere. It's been growing denser as the Pluto-Charon system swings through its closest approach to the Sun and surface ices warm and sublimate; and new results show that the atmosphere is warmer than expected because it contains about 0.5% methane, enough to cause a greenhouse effect (relatively warm, of course: it's still a chilly minus 180 degrees Centigrade). It's also warmer in the higher reaches of the atmosphere than near the surface, because sublimation of ices cools the surface while sunlight warms the resulting gases from the top down. When we get the same inversion effect here in London, smog is trapped under the warmer upper layer. Is there smog on Pluto, and if so, what is it made of? Still, pretty amazing that we can tell so much about a body so far away.

I was watching The Sky at Night yesterday, which had a nice bit on the Cassini orbiter's latest findings about Enceladus and Titan; there was also a piece on the various satellites currently orbiting the Moon, including the news ( to me) that the high-resolution camera aboard the Japanese SELENE (Kaguya) satellite had taken a picture of the Apollo 15 landing site. Turns out this happened last year, but I somehow missed it.



It's the pale blotch in the centre of the photo, visible because when the LEM return stage took off, its exhaust plume blew away dust on the surface, uncovering lighter material beneath. NASA is sending a new satellite, the Lunar Reconnaissance Orbiter, to the Moon later this year, with an even more powerful camera It's main mission os to study the poles, but it would very neat if it could take photographs of the Apollo 11 landing site, forty years on.

6 Comments:

Blogger PeteY said...

It's a pity the dark patch in the middle of the bright patch still isn't resolvable as the descent stage, then we would have something against the idiot deniers. Stil, I'm sure no evidence would convince the worst of them that the moon landings took place.

March 04, 2009 12:42 am  
Blogger Paul McAuley said...

The resolution isn't up to spotting the landing stage, but the Japanese think the dark patch might be its long shadow. The new NASA probe carries a camera with a resolution of 0.5 metres, good enough to spot a LEM landing stage or a rover.

The Japanese also produced a 3-D rendering of the area that precisely matches the photos taken by the Apollo 15 moonwalkers, but this hasn't satisfied the deniers - like you, I think they've reached a stage where the perceived conspiracy about fake moon landings has now been extended to include their efforts to prove there was a conspiracy. Still, it would be nice if NASA did for them what it did for the face-on-Mars crew.

March 04, 2009 8:52 am  
Anonymous Nathan said...

I constantly have to fight the "it was all faked" battle with the students I teach. The ignorance and bloody-minded denial of supposedly bright kids is frightening. Despite all the technology they use without comment- mobile phones, ipods, the Internet, satellite television, velcro for crying out loud- they refuse to admit that humans could have walked on the moon! I was born whilst Apollo 14 was on the Moon and it has dominated and haunted my psyche and imagination all my life. When I hear kids dismiss it as 'a story', and I look at the resurgence of certain organized religions, I fear we are on the cusp of a new, twisted dark age.

March 04, 2009 1:17 pm  
Blogger Paul McAuley said...

Hi Nathan, That's so sad. Don't know how old your students are, I was 15 when Apollo 14 landed, and no one then questioned the reality. Maybe it's because we have all this advanced tech now that your students can't believe that the US could send men to the Moon forty years ago? And to be fair, since they weren't born then (and in some cases their parents might not have been born then, I can sort of understand why they can see that it's not as relevant as you and I think it is.

This is a useful resource for anyone who believes or is tempted to believe the hoaxers:

http://www.badastronomy.com/bad/tv/foxapollo.html

Of course, it's rather more difficult to argue against general indifference, except by trying to make it as real and as detailed and as amazing as possible. Amazing that it was done, then. Even more amazing from our point of view that they managed to do it, way back then.

March 04, 2009 11:35 pm  
Blogger PeteY said...

Thanks for the useful link, I'll send it to my deluded friend.

Of course the bad astronomy guy just concentrates on the more credible skeptical arguments, but I've heard other, more crazed ones asserted on TV. For example, one nut (I forget names, so at least they can't sue me) confidently asserted that the van Allen belts were some kind of shield against the "lethal radiation of deep space," rather than the belts of radiation that they actually are. Hence, of course, you couldn't go beyond them and survive. Sound reasoning from a completely false premise.

I just hope we get a rover to one of the landing sites before long. Hopefully that'll convince some people. Maybe one of the Google Lunar X Prize contestants will make it.

March 05, 2009 5:33 am  
Anonymous Nathan said...

Thanks for your comment Paul. I think you are largely correct- it does seem a long time ago and tech is taken for granted today. I also think there is a degree of anti-Americanism in the attitude- (given the rather shameless behaviour of the US in the near past, understandable) the kids who I teach (who it has to be said come from non-Western backgrounds) rubbish just about anything American (except the products of the entertainment industry) for no reason apart from they think they should. Equally, they are unaware or uninterested in the impressive progress the second wave of space-capable powers (of which many of them have a cultural or ethnic connections). I really do not think you can dismiss the utilitarian consequences of economic deprivation or the tendency for hokey memes to propagate in any ill-informed, financial knife-edge population.

March 05, 2009 10:17 am  

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