There is ice on Mars.
Photos of the spots where the Phoenix Mars explorer dug a few days ago show that some of the white material that was exposed has disappeared. That almost certainly proves it’s ice, water in solid form, that has sublimated (that is, gone directly from a solid into a gas, rather than melting from a solid into a liquid). If the white stuff they’d uncovered had been salt, it wouldn’t have sublimated.
As I wrote yesterday, Phoenix has been digging in a new spot. That effort stopped when they hit a hard layer: more ice?
They also seem to have figured out (though they haven’t explained) what was causing those memory overruns yesterday. They’re uploading a software patch to address it. In the meantime, they’re downloading the new scientific data each day and not trying to store it in case it gets bumped out.
The Phoenix explorer on Mars continues to bake the soil samples it’s dug up but no signs of water (or anything else interesting) have been reported yet. It’s been digging in some new spots, too.
Yesterday NASA noticed that Phoenix generated an unusually large amount of“housekeeping data”, though. Housekeeping data is information Phoenix stores about the files and data it’s storing, and it has a high priority. For some reason they don’t yet understand, Phoenix generated a lot of it yesterday; so much that there wasn’t room for all the new scientific data (mostly photos the probe took) and some of it was “pushed out”. Phoenix appears to be working fine, and nearly all the photos can be re-taken, but scientists are concerned until they can figure out what’s causing all the housekeeping data.
A second successful soil dump in as many days for the Mars Phoenix lander. Yesterday they finally managed to get enough soil into the TEGA to do some analysis. Today they’ve managed to sprinkle a sufficient amount of dirt into the Microscopy, Electrochemistry, and Conductivity Analyzer (MECA).
The MECA will perform some chemistry of the sort that most people might imagine when they think of chemical analysis: it’ll test the soil for its pH (level of acidity or alkalinity), determine some of the minerals in it, look at the particles of dirt under a microscope (the presence of some clays would be a hint that there’s been liquid water in Mars’s past), and see how well it conducts heat and electricity.
Result! The Phoenix Mars lander has an oven full of dirt! Now the Thermal and Evolved Gas Analyzer (TEGA) can get to work. And “work”, for the TEGA, is basically “bake and sniff”.
Maybe you’re wondering why baking dirt is a useful thing. Wonder no longer.
Every element in the periodic table has its own atomic mass. Some bright spark thought that it should be possible to make use of this uniqueness to be able to identify what elements are in any unknown clump of “stuff”. That bright spark came up with a mass spectrometer to do this. The spectrometer takes atoms of “stuff”, gives them a little positive or negative charge (ionizes them), and then shoots them through a controlled electromagnetic field. That field will exert forces on the charged atoms and cause them to deflect from the path they’ve been shot on. Particles of greater mass will deflect less than ones with less mass in the same field. By measuring that deflection and knowing all the other variables (the amount of charge you’ve applied, the strength of field you’ve created, etc.) you can determine the masses of the atoms. And because they have unique masses, you can match that up to the periodic table and know what’s in your “stuff”.
To get your individual atoms and be able to ionize them you need to be able to make them into a gas. That means baking them, heating the “stuff” up until some of it, at least, starts to vaporise. Then you do your mass spectroscopy, and bob’s your uncle.
This is what the TEGA on Phoenix is. It’s a high-temeprature oven to vaporise the dirt, and a mass spectrometer to determine what elements are in the dirt. It’s so sensitive, in fact, that it can differentiate isotopes of the same element. That’s important, because information about the ratios of different hydrogen, oxygen, carbon, and nitrogen isotopes might provide info about whether conditions on Mars have ever been suitable for some type of life. Now that TEGA’s finally got a big lump of dirt in it they can start doing that.
Stymied by clumping Martian dirt, the Mars Phoenix explorer tried out the shaking-scoop method I mentioned yesterday to see if that would have a better chance of getting soil into the analyser. It seems to have worked.
The digging drama on Mars continues.
Phoenix did dig up a nice, big clump of Martian soil, and dumped it into the receptacle where it should be analysed. However, it seems that Martian dirt is far clumpier than the NASA boffins had guessed, and none of it slipped through the intended gaps in the receptacle screen to the analyser below. Phoenix shook the screen for 20 minutes yesterday but only a couple of specks of dirt fell inside.
More shaking is planned, and then it’s on to Plan B:
The arm delivered the first sample to TEGA on Friday by turning the scoop over to release its contents. The revised delivery method, which Phoenix is testing for the first time today, will hold the scoop at an angle above the delivery target and sprinkle out a small amount of the sample by vibrating the scoop.
The Phoenix Mars explorer has been busy.
It’s exercised its scoop twice, picking up bits of dirt and then dumping them out. The oven that will “bake” the dirt and analyse the gases that evolve from it has been tested too, and is in working order. That means Phoenix is ready to scoop some dirt up for proper analysis.
It’s also taking photos that are being rendered into colour. The photo it took of the ground where it did the second test scoop show a patch of white stuff underneath the topsoil, much like was seen in the landing site underneath the Phoenix itself. Until they analyse some of it NASA won’t know for sure if that white stuff is ice or mineral salts or something else.
Click image to enlarge. Courtesy of NASA JPL.
There’s also some drama. The Mars Odyssey – which has been in orbit around Mars for some time, and relays info between Phoenix and Earth – has gone into “safe mode”. It’s programmed to do this when something goes wrong: it stops what it’s doing, shuts off non-essential systems and waits for instructions from Earth. NASA’s trying to figure out what triggered safe mode. In the meantime they’re using a second orbiter, the Mars Reconnaissance Orbiter (MRO), to communicate with Phoenix (although that’s not exactly smooth sailing, either: they’d previously stopped using MRO a few days ago when one of its radios failed temporarily, though it’s been working since then).
The Phoenix Mars lander has landed: safe, and on a nice, flat surface. Here are some of the early pics coming back.
Phoenix is a robotic Mars lander spacecraft. It was developed by a partnership of NASA, the Canadian Space Agency, several European countries, and the aerospace industry. Phoenix launched last year and is now getting very close to Mars, where it will try to chart the history of water on the planet and identify environments where microbial bits of life could exist.
It’s scheduled to land on Mars a week from today. That alone would be exciting enough. But I’ve been whipped into a frenzy by the fact that in the last few weeks scientists on the programme have been Twittering as if they were the Phoenix robot. About two hours ago Phoenix fired its engines for three seconds to make a landing trajectory adjustment. Now that is cool.
NASA’s Phoenix Mars lander illuminates Launch Pad 17A as it lifts off aboard a Delta II 7925 rocket at 5:26 a.m. EDT 04-Aug-2007 from Cape Canaveral Air Force Station. Phoenix will land in icy soils near the north polar, permanent ice cap of Mars and explore the history of the water in these soils and any associated rocks, while monitoring polar climate. Landing on Mars is planned in May 2008 on arctic ground where a mission currently in orbit, Mars Odyssey, has detected high concentrations of ice just beneath the top layer of soil. Photo credit: NASA/Tony Gray and Robert Murray