Bill Boynton
October 9, 2008

• 4 samples analyzed fully
• TA4, Baby Bear: Disturbed surface sample taken soon after landing
• TA0, Wicked Witch: sublimation lag from bottom of Snow White trench. It had a small amount of ice with it (~1% or less)
• TA5, Rosy Red: A well documented undisturbed surface sample
• TA7, Burn Alive: A deep sample taken beneath Rosy Red to look for differences as a function of depth.
• TA1, A “blank” sample: It has just been analyzed, and some data arrived an hour ago. It is in lieu of the OFB, for which we had a failed delivery due to wind blowing the sample off target.
• All samples show release of CO2 at low temperature (250 C to600C)
• This low-temperature CO2 could be from FeCO3, oxidized Marsorganics, or oxidized terrestrial organics.
• • Today’s data on TA1 looks like we can eliminate the last of these.
• The amount is low, on the order of 0.0x% carbonate (based on CO2 volume)
• All samples show release of CO2 at high T (700 C to 1000 C)
• This CO2 is almost certainly due to CaCO3.
• Two samples (Baby Bear and Wicked Witch) showed a smallamount of high-T release of CO2
• • On the order of 0.0x % carbonate
• Rosy Red had much more CaCO3 (on the order of 5%)
• Burn Alive has some intermediate amount of CaCO3, but it is too soon to know for sure how much.
• We have a new way to analyze the released gases now that we understand the nature of their release pattern.
• We collect all of the gases in a certain temperature range and release them for analysis all at once.
• We record the pressure of the gases released as a function of time to know the temperatures of release.
• The total pressure is a good measure of the amount of gas released.
• This approach allows us to have a much higher signal-to-noise ratio for the isotopes of CO2.
• We have been able to demonstrate excellent precision on our measurement of count-rate ratios
• Conversion to isotope ratios depends on getting high precision on our calibration gas, but we expect that to not be a problem.
• Other sources of systematic error must also be evaluated
• For Burn Alive, we got good data on both the low-T and high-T CO3 release.
• For mass 45 we get ± 1.5 ‰ (requirement is 5 ‰)
• For mass 46 we get ± 1.4 ‰ (requirement is 10 ‰)
• Isotopic ratios could help argue for low-T CO2 being from Mars organics rather than carbonates.
• We have three ovens available.
• Two have doors only partially open (tented) TAs 2 and 6.
• – TA6 is slated to get Rosy Red this weekend
• The third one still has closed doors.
• – We can have confidence at least one door will open fully.
• Desired samples?
• Rosy Red (a re-do of what was done before, originally because we had a plugged porous frit on the oven outlet that sealed the gas in the oven until it spontaneously unplugged.)
• Another dry sample like Wicked Witch or Sorceress (dry
  sublimation lag)
  
• – This sample is to confirm that it had much less carbonate and to see if there is any difference in isotopic ratios of carbonate
• An icy sample from wherever it is felt we have the best chance of getting a good delivery

– This is mainly to get the D/H ratio of the ice.