Phoenix: “It Must Be Ice”

Phoenix scientists have been keeping an eye on the white material uncovered in a trench dug by the lander’s scoop. Dice-size nuggets of the bright material have vanished, convincing scientists the material was frozen water that vaporized after digging exposed it. The image here is a “movie” showing the material disappearing after four days. “It must be ice,” said Phoenix Principal Investigator Peter Smith. “These little clumps completely disappearing over the course of a few days, that is perfect evidence that it’s ice. There had been some question whether the bright material was salt. Salt can’t do that.”

The chunks were found at the bottom of a trench informally called “Dodo-Goldilocks” when Phoenix’s Robotic Arm enlarged that trench on June 15, during the 20th Martian day, or sol, since landing. Several were gone when Phoenix looked at the trench early today, on Sol 24.

“We know the ice is H2O but that doesn’t tell us much,” Smith said. “It is the impurities in the ice and the soil above the ice that tell us the history and if it is a habitable environment. We’ll now proceed to get the secrets out of the ice and use our instruments.”

Also on Thursday engineers said while digging in a different trench, the Robotic Arm connected with a hard surface that has scientists excited about the prospect of next uncovering an icy layer. Ray Arvidson, co-investigator for the robotic arm, said the hard layer was at the same depth as the ice layer in our the Dodo-Goldilocks trench.

The new trench, called “Snow White 2” trench, is in the middle of a polygon at the “Wonderland” site. While digging, the Robotic Arm came upon a firm layer, and after three attempts to dig further, the arm went into a holding position. Such an action is expected when the Robotic Arm comes upon a hard surface.

The Phoenix science team spent also Thursday analyzing new images and data successfully returned from the lander earlier in the day.

Meanwhile, Phoenix apparently suffered a problem with its flash memory on Tuesday, similar to, but not as serious as the problem that the Spirit Mars Exploration Rover encountered about 20 days after it landed on Mars back in 2004. The spacecraft team at Lockheed Martin Space Systems in Denver is preparing a software patch to send to Phoenix so scientific data can again be saved onboard overnight when needed. Because of a large amount a duplicative file-maintenance data generated by the spacecraft Tuesday, the team is taking the precaution of not storing science data in Phoenix’s flash memory, and instead downlinking it at the end of every day, until the conditions that produced those duplicative data files are corrected.

“We now understand what happened, and we can fix it with a software patch,” said Phoenix Project Manager Barry Goldstein of NASA’s Jet Propulsion Laboratory, Pasadena. “Our three-month schedule has 30 days of margin for contingencies like this, and we have used only one contingency day out of 24 sols. The mission is well ahead of schedule. We are making excellent progress toward full mission success.”

The Phoenix team will hold a press conference today (Friday) at 1:00 pm EST to discuss the latest findings.

Sources: Phoenix News
The Tucson Citizen

14 Replies to “Phoenix: “It Must Be Ice””

  1. I’m not thoroughly convinced yet, but it is (to me) the best news to come from this program yet. Definitely exciting!

  2. Looks to me like there are big white chunks just outside the scoop trench (at the top of the picture) that haven’t changed between the two pictures. Why hasn’t that evaporated?

    And, I still see white inside the trench, so only some of the “ice” evaporated?

    Not convinced at all. Sounds to me like the scientists are trying to make these images “fit” their paradigm.

  3. Even though it may look like ice and behave like they would expect (and they are probably right), I would be more confident of this analysis if they confirm this by test. As far as I remember, only one test has been done so far, correct? The first test was negative for H2O but NASA was working out the testing procedure (getting the sample into the oven). Does anyone know when NASA will try again? Do they have to wait for the FLASH memory fix?

  4. I’m not sure how powerful that arm is, or if the intensity of the scooping can be increased, but, why don’t they just go over the same dig until more ice is revealed at the surface? Either that, or just dig deeper into the same hole, thus bringing up more ice?

  5. I’m not sure it gets cold enough to freeze carbon dioxide, although with a low pressure it could be a lot higher than normal.

    Anyone have an idea what temperature CO2 freezes at Mars’ low pressure?
    Been a long time since I’ve worked through phase diagrams to figure this out.

  6. I think it may be ice.It is looks very white.It is very exciting news for us.

  7. Bobby Says:
    June 20th, 2008 at 6:40 am
    “Not convinced at all. Sounds to me like the scientists are trying to make these images “fit” their paradigm.”

    Well, when you see something disappear before your eyes, and you already know that water ice is not far below the surface from measurements made by other spacecraft, I think it is well within reason to make that leap. I guess it’s a good thing they have loads of equipment on board that will soon be able to tell us for sure.

  8. The Mars researchers all say that the polar caps of Mars are predominately carbon dioxide, so there is little to think that carbon dioxide cannot exist near the martian poles. That alone makes it more likely that this is CO2. At the Phoenix website or the Planetary Society’s blog page, there is a two frame animation of the disappearance of the white stuff. If you look carefully, there is also dark stuff, some small chunks, that disappears, and it’s not just a change in shadow. Now what could that mean? If the dark stuff is neither water or CO2 ice, how to explain it? If I’ m not hallucinating, and if the dark stuff is not an ice, then there is something present that can make small quantities of mineral go away.

  9. Bobby, you asked good questions. I think the reason the isolated chunks of ice sublimated (goes directly from solid to gas) so quickly is that those pieces were insulated from the rest of the buried ice layer by soil. Water conducts heat quite well. The isolated pieces were warmed by the Martian air and exposed to ambient light over most of their surfaces. However, the buried ice layer was only exposed on the top surface. The rest of the buried ice layer pulls away heat from the surface, due to the high heat conductivity of water.

    As far as the “white” chunks that didn’t sublimate, they are not composed of the same material. Remember that these are not the same black and white photos you are used to. Each image is taken at a specific wavelength (color) using color filters. The images where the ice appears brightest are taken at the blue end of the spectrum. Blue photos are usually exposed much longer so the ice seems brighter in them. Looking at the chunks that didn’t sublimate using different filters reveals that they are different from the ice. A false-color animation is available at

  10. I was under the impression that the University of Arizona was running these experiments, not NASA.

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