Phoenix’s scientific team team held a press conference today to officially make their big announcement, which was fairly evident from pictures on the Phoenix website late yesterday: They found what they have been looking for. “It is with great pride and lot of joy that announce today we have found the proof that we have been seeking that show that this hard, white material is water ice,” said the project’s principle investigator Peter Smith. The image here shows a trench dug by Phoenix’s robotic arm scoop that exposed a white area, and left a couple of small chunks of white material, which scientists thought could possibly be ice. A few days later, the ice is gone. “In the course of sitting through the cold and very dry Martian environment for several days, it sublimated,” said Mark Lemmon, co-investigator on the Phoenix’s Surface Stero Imager. “The ice went away into vapor without any melting taking place.” But how do the scientists know for sure this is water ice?
“We can easily and confidently rule out that its carbon dioxide ice,” said Lemmon. “There are certainly times of the year that there would be CO2 ice at this location but with the temperatures we are measuring there, it would be the equivalent of water ice existing on Earth at 140 degrees. It wouldn’t be there very long, and wouldn’t be there long enough for us to take its picture, and it wouldn’t last the night. We’re very confident this is not CO2 ice. We’re ruling out salt, because salt doesn’t react like this. We’re confident now that this is water ice. We’ve hit what we’re looking for. The job now is to find out what is mixed in with the ice, how much salt is there, how many organics are there, and these are the things we’ll need TEGA and MECA to solve.”
TEGA is the Thermal and Evolved Gas Analyzer that “bakes and sniffs” out the chemical composition of the soil, and MECA is Microscopy, Electrochemistry and Conductivity Analyzer, a wet chemistry lab that measures levels of acidity, minerals, and conductivity in dirt samples.
Smith said the landing site was carefully chosen as a place where ice was very likely to exist, based on subsurface hydrogen detected by the orbiting 2001 Mars Odyssey spacecraft.
The team is now going to look for two things associated with the ice. “Does the ice melt, and does the melted ice environment allow a habitable zone on Mars,” said Smith. “That is a place where organic material and energy sources combined with liquid water can be a habitat for Martian life. We don’t have instruments that detect life itself. We’re looking at this stage for habitability, and it will be future missions that will look for life.”
The trick now is to get some of this white material into the TEGA instrument ovens before it sublimates. “The plan for sampling the ice is to gather it up rather quickly using the power tool called the Rasp and deliver it to the TEGA within 30 minutes,” said Ray Arvidson of the Phoenix team. The TEGA ovens do have airtight seal so it’s possible that the ice could go to a liquid stage while being heated. However, because of Mars low surface pressure, the boiling point of water on Mars is 4 Celsius.
Now that they know the ice is there, the scientists want to know more about the soil and why it seems to have a sticky, clumpy consistency. “Knowing that this is ice here, it allows you to speculate there are certain salts that mixed with ice can melt at low temperatures” said Smith. It’s very tempting to get a sample of this into MECA as soon as we can. Right now we have some speculations but no real interpretations available yet. I truly believe we will have answers for you by the end of the summer and hopefully earlier, so stick with us.”
The robotic arm is now digging in a new area in the trench called Snow White. They’ve dug a double trench and have hit a hard layer of ice. The team will try other techniques to see how hard the ice is, and how deep it goes, and try to dig down deeper. They will take their time, however, to make sure the sequences they use for the scraper and rasper work correctly (so as not to repeat having delays similar to what happened the first time they tried getting the soil into TEGA.)
Project manager Barry Goldman also said that the problem with Phoenix’s memory is understood, and two software patches being created to solve the problem of that used up all the space on Phoenix’s version of a flash drive.
Source: Phoenix Press Conference