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David Darling's Newsletter #18


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January 11, 2004


Contents

1. Meanderings
2. Views From Mars: Part 1
3. Bookends


1. Meanderings

Thanks to everyone who's joined the newsletter over the past few weeks, bringing our number to about 420 spread across six continents (come on Antarctica!). If you currently get the newsletter from Yahoo and would like to receive it directly from me instead – to avoid the ads, etc – just send me an e-mail.

The website itself is going from strength to strength and now gets close to 20,000 visitors a week on a steeply rising curve. The front page contains several fresh news items every day, while the encyclopedia now has some 2,500 entries – a number that's being added to week by week. I've also put a Googol search bar on the main page that lets you search the site for specific topics as an alternative to looking through the lists of encyclopedia entries. It works quite nicely – give it a try.

Well, the science story of the moment is the Mars landers and what they may find in the coming weeks. This is the first of several newsletters that will be keeping you up to date with developments and discoveries as we rock and roll along the Martian surface. Get ready for a fascinating ride!


2. Views From Mars: Part 1

Maybe it's a bit to early to be writing an obituary for the British-built Beagle 2, which hitched a ride to Mars aboard the European Space Agency orbiter Mars Express and hasn't been heard from since it separated from its mothership on December 19. The latest attempts to contact it via Mars Express have failed and there are now increasing fears that it may have crashed into the planet on Christmas Day. The fact is we simply don't know what's happened to Beagle. Unlike the Mars Exploration Rover spacecraft that are equipped with transmitters that send out tones at each crucial stage of their descent through the Martian atmosphere (when the heat shield is ejected, when the parachute opens, when the airbags deploy, etc), Beagle had no way of telling us what was going on as it dropped to the surface. We know it was bang on course for a touch down on Isidis Planitia when it detached from Mars Express, and everything else looked OK with the spacecraft at that point. But now we're left guessing: Did the heat shield fail? Did the parachute or airbags fail to deploy properly? Was one of the airbags punctured by a sharp rock? Did Beagle (about the size of a bicycle wheel and the mass of a small man) roll down the slopes of that forbidding looking crater that was imaged (too late, from orbit) right in the middle of its projected landing zone? If I were a betting person I'd put my money on an airbag failure (earlier versions of the airbags had failed in tests and there hadn't been enough time to properly test their replacements) or the spacecraft coming to rest in a position from which it couldn't transmit directly to Earth or to one of the Mars orbiters. Maybe hi-res imagery from orbit will spot its parachutes or airbags and we'll discover more about its fate. Or, by some miracle, Mars Express will pick up its signal in the coming days. But it seems most likely that Beagle 2 has joined the long list of Mars explorers that met with a sticky end – nearly two-thirds of all spacecraft launched toward Mars since the early sixties haven't completed their missions. Prior to the current batch of probes (Beagle and the two MERs), only 13 out of 34 missions had been successful and only 3 out of 13 landing attempts. Quite a few of those landers were early Soviet craft. The three previous landing successes have been Viking 1, Viking 2, and Mars Pathfinder. To this select band has now been added (touch wood) the first of the MERs, the Spirit rover, which is standing on its lander, with wheels unfolded and all instruments functioning, ready to trundle out on to the Martian surface.

It's a mouth-watering prospect. Within a few days, Spirit will edge its way down, carefully avoiding (we hope) damaging its solar panels on the not-quite-neatly-collapsed airbags, and begin its explorations. Already it's sent back stunning color photos from its perch inside the 90-mile-wide Gusev crater. Gusev has a big channel running into it (Ma'adim Vallis) which probably filled it with water more than 3 billion years ago. Spirit is going to be trying to find out, from a close examination of its surrounding rocks, how long that water was there for and whether it may have helped nurture life. Unfortunately, the MERs don't carry any biology experiments, as Viking and Beagle did, so they can't test for the presence of past or present life directly. But they can certainly find geological clues that would hint that the conditions may have been right for life to appear. One of the first targets of the rover will be what looks like a small, shallow, dust-filled impact crater, nicknamed "Sleepy Hollow," that lies about 50 feet from the lander. It looks like some rocks have been exposed on the side of this feature that will provide a kind of portal into Mars' past. But what I'm most excited to find out about is the weird clay-like substance that was revealed when the airbags were retracted a few days ago. NASA scientists have already admitted to being baffled by this stuff. It looks exactly like soil or sand that is sticking together in clumps because of moisture. But we all know – don't we? – that there can't be liquid water on the surface of Mars! Boy oh boy, if it turned out to be mud we'd have to rewrite the textbooks and speed up those manned landing plans which Bush may be announcing this week (although it is election year, don't forget!) Also, some of the rocks close to the lander have some interesting shades to them – ochre and even a hint of blue - so they'll make attractive targets for early investigations too.

OK folks, we have an exciting few weeks to look forward to as Spirit begins its adventure. And don't forget that its sister craft, Opportunity, is closing in fast - scheduled to make planetfall on January 24 on Meridiani Planum where gray hematite has been discovered in abundance – a strong sign of a watery past.

I can hardly wait. With Stardust scooping up bits of cometary dust and heading back to Earth with it, and Cassini/Huygens due to arrive at Saturn in June this is going to be one heck of a rollercoaster ride in space. Stay tuned. I'll be back with a further update on the Mars explorations in a couple of weeks. Also check the bulletin board for discussions on the possibilities for Mars life and have your own say.


3. Bookends

You can find out about my latest book, The Universal Book of Astronomy, and, by going to the front page of my website, get further information about all my books, including Life Everywhere, The Complete Book of Spaceflight, Zen Physics, and others. You can even read the first two chapters of many of them. Next due for publication, in August 2004, is a book on weird and wonderful aspects of math, including higher dimensions, almost-impossible mazes, Mobius bands and Klein bottles, and the incredible ham sandwich theorem!


Until next time,
Best wishes,
David Darling