Thoughts from a dying probe

I’ve blogged on and off about the Phoenix explorer probe, and its search for water on Mars. It’s just about done its mission: it found the water it was looking for (in block ice and snow form) and sent massive amounst of data back to NASA. Phoenix’s batteries are now dead, and while there may be a few brief Lazarus-mode moments, it’s effectively dying.

Read its touching dying thoughts in this guest spot on Gizmodo.

Dropping temperatures measured by Phoenix

Mars Phoenix to chemically test for water

The Phoenix Mars lander is ready to sample a scoop of icy ground and hopefully prove, chemically, that that white shiny stuff is water.

They’ve done thermal tests of the soil to see what time of day is best to minimise sublimation (i.e., turning into gas) of any ice they expose and dig up. They’ve given the topsoil a good digging and scraping to expose a promising area. They’ve monitored how quickly the ice in newly exposed soil sublimates. They’ve planned their rasping, digging, and dumping moves. And they’ve cleared the scoop and opened the TEGA doors.

TEGA doors open on the Mars Phoenix lander

More Mars data

The Phoenix explorer on Mars is now returning lots of cool new data.

  • Earlier samples of soil have been put through some analysis inside Phoenix; the resultant data, for NASA scientists, “was like winning the lottery.” For example, the soil at the landing spot appears to be similar to surface soils found in the upper dry valleys in Antarctica. One scientist said, “This is more evidence for water because salts are there. We also found a reasonable number of nutrients, or chemicals needed by life as we know it.”Another said, “At this point, we can say that the soil has clearly interacted with water in the past.”
  • A couple of days later the digging arms on Phoenix scraped a new area, and photos of the scraped spot indicate “that surface soil, subsurface soil and icy soil can be sampled at a single trench.”

Are we sure it’s ice on Mars?

Pretty sure, yes. Some people have asked whether NASA is jumping the gun, since solid CO2 – dry ice – also exists in abundance on Mars, and it can sublimate (turn into gas) as well. Maybe it’s that.

As this recent Q&A posted on Wired explains, it can’t be CO2 because it’s currently ‘way too warm there (they landed during Martian summer) for CO2 to exist in solid form at all. It’s still cool enough for it to be solid H2O under the soil that gradually sublimates when exposed to heat from the sun. That’s why they think it’s ice.

That Wired page also has a link to a nifty weather report from Mars on the Canadian Space Agency’s website.

Proven: you can get ice with your drinks on Mars

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.

Mars Phoenix continues to dig and bake, but has memory overrun

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.

Even dirtier

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.

Ladies and gentlemen, we are full of dirt

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.