October 2005

Interesting pictures have come in from the Cassini probe going around Saturn's moon Titan this month, showing what astronomers believe to be a shoreline. The actual image from NASA is shown here on the upper right, in glorious black-and-white grain-o-vision (readers of the “dead tree” edition will be used to this by now). It's actually a plot from a Synthetic Aperture Radar (SAR) scan, so colour is a no-show. The blacker stuff concentrated in the lower right is the prospective sea, the grainy stuff the land.

Down below we have a similar shot of an alkali lake on Earth. Not THE Alkali Lake, beloved of X-Men and Wolverine fans, but a lake which is rich in salts. As the lake undergoes seasonal fluctuations, deposits of salts build up in intriguing patterns. These patterns seem to exist in a slightly more directional form in the Titan image, suggesting that Titan has some bodies of fluid that do deposit some form of solid. But Titan's seas are likely to consist of hydrocarbons not entirely unlike the liquid sloshing around inside a gas lighter, but with more in the way of tar and crud dissolved in it. This is possibly what leaves the ridges.

Meanwhile, back on Mars, things are shifting around more rapidly than we'd previously realised. There has been some debate on the age of fluid-carved features on Mars, but now no more. Areas of Mars previously photographed in 2002 were compared with some from last April, and there were some gulleys found that weren't there before. Those are the slightly less grainy images from NASA here on the lower left. Spot the difference.

Mars is also now on the “Visit List”, after returning to the moon and proving the technology there. Another Mars initiative was mooted when President Bush Snr. became bogged down in Iraq, so there is a fair degree of scepticism as to whether its a distraction or sacrificial budget cut victim this time around. But things are a little different, with the shuttle still grounded for the foreseeable future, and the US with a number of obligations to fullfill to its international partners regarding it. It might even unkindly and ironically be recalled that when the International Space Station was conceived, the US voiced loud concerns over whether the Russians would be able to commit through to the end of the task. The Russians, of course, saw things the other way.

One of the options NASA has is to re-use shuttle components, as mentioned a couple of months ago. Some of the reasoning behind this is getting clearer. There's nothing wrong with shuttle engines, for instance. OK, so they're a bit expensive to maintain, but using them is cheaper than developing new alternatives. And the external tank, is fine. So what if the foam falls off? Just stick the payload on the top where it won't get whacked by the chunks.

The huge solid rocket motors are very powerful, and they're recycled after each flight too. A known tendency to turn into cutting torches on frosty days, but that can be dealt with. Besides, all the major leakage problems are solved by stacking the parts in a traditional vertical configuration on the manned launches. For manned launches, a single solid motor boosts a small fuel tank with a couple of shuttle engines on the bottom. Stuck on the top of that is a 4-man version of the Apollo capsule, slightly bigger than a Russian Soyuz capsule, so no wings are needed.

What about cargo though? Well, the answer to that is one that has been around for a long time. In the 1970's the late G. K O'Neil suggested a “Shuttle 'C'” design using a non-reusable frame holding shuttle engines to hoist an external tank and payload (on the left, shown in a publicity image from Boeing). He envisaged the payload in a container on the side of the external tank, but current wisdom is that it's much safer on the top and longer boosters will give a lift of 100 tonnes to a low orbit. Enough, perhaps, to put several space station parts up at once.

Meanwhiles, there is no manned US launcher. The US Senate has had to discuss changing the law to allow them to buy Russian Soyuz launches (on the right) to meet their obligations. US Law, it seems, forbids the purchase of rocket technologies from Russia because the Russians help Iran. Well, I suppose it hurts their pride less than using Chinese rockets. Meanwhile, the EU is collaborating with Russia on the design of a replacement for Soyuz called Kliper, a winged six-seater which will complicate the political field a little.

On then to affairs in the asteroid belt, or at least one asteroid from it that wanders in our direction occasionally. Asteroid Itokawa (hope I got the pronunciation right, it's named after the late rocketeer Hideo Itokawa, father of Japan's space program) is getting a visit from the Japanese probe Hayabusa (not the Suzuki Hayabusa GSX1300R, fastest production bike in the world) which has already achieved the not insignificant goal of parking itself a mere 20km away - without a kick-stand. It took the picture on the left, courtesy of JAXA the Japanese space agency. Not a very regular shape. Plans are to land on it, collect a sample, and fly back to Earth with it. But there's more. It has a little hopping robot that it'll drop down to take samples with, firing three sampling devices into the crust. I hope the asteroid doesn't mind...

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