Note: I am posting my old blog entries from elsewhere on the internet. This entry was originally posted on 6/11/08.
Another update from Phoenix. I haven’t embedded the URLs because my brain is fried, please copy and paste to see the pretty pictures.
I am finishing up another 4 day stint as Instrumentation Sequence Engineer (for real this time, not just shadowing someone else) for the TECP, and I thought I’d send you all another update.
The big story here for the last week or so has been TEGA (Thermal and Evolved-Gas Analyzer), an instrument containing 8 ovens that is designed to take a 2 mm by 2 mm sample of material, bake it, and examine the gas that comes off of the sample (what they are calling bake-and-sniff in the press materials). When I last wrote to you all, we had told TEGA to open the cover doors on one of the ovens, and gotten ready to deliver a sample of dirt from the scoop at the end of the robotic arm. Well, we dumped the dirt onto TEGA, but the dirt was full of clumps that blocked anything from getting through the screen! (http://phoenix.lpl.arizona.edu/images.php?gID=3567&cID=52)
We don’t want to waste any ovens, because TEGA only has 8, and each one can only be used once – we need each of them. So, how to get the sample into the oven? It turns out that TEGA has the ability to vibrate very slightly to help knock material in, so the team decided to shake TEGA, take a picture of the surface, shake it again, take another picture, and so on. The results from the first attempt showed some slight shifting of the material (http://www.nasa.gov/mission_pages/phoenix/images/press/13182.html), but only 2 grains of dirt got in (They monitor how much material gets in by keeping track of the intensity of an LED at the entrance to the oven. If the light dims, then a bit of dirt has passed in front of the LED and into the oven.).
After much more discussion, the team decided to try again. Part of the discussion the team had to have is that the motors controlling the shaking only have so much lifetime, and is it okay if we burn them out on this one measurement? A lot of the decisions made before the daily plan gets put into software code involve minimizing the risk to the health of the spacecraft and the instruments, and determining what is an acceptable level of risk.
In the meantime, while we were shaking TEGA, my instrument (TECP) continued to take measurements of temperature and humidity several times a day, and two times at night – a first for the mission! The team also did a “sprinkle test” to try a different method of delivering a small amount of dirt to an instrument. This sprinkle technique was put together for some of the other components of MECA, the suite of instruments that the TECP is part of. One of our components is the Optical Microscope, which has a row of small targets (such as magnets) that we want to sprinkle with dirt and then take very high-resolution images of to study individual grains of dirt (you can see some initial images of the dust that’s fallen on the lander since landing here: http://phoenix.lpl.arizona.edu/images.php?gID=3104&cID=46. These are the highest-resolution images ever taken on Mars). Rather than tilting the scoop and dumping the whole sample on the instrument like what we did with TEGA, the sprinkle technique is to hold the scoop steady and run the rasp, a little vibrating scraper tool (which was designed for scraping through any ice we hopefully encounter) in order to gently shake out small particles. We tested this on the white cover of the Optical Microscope, and you can see the results here (http://www.nasa.gov/mission_pages/phoenix/images/press/13339.html) – it worked perfectly! We will be using this technique for future deliveries to TEGA as well.
So how did TEGA do during its second sol of shaking? At today’s Midpoint Meeting (the meeting where the downlink team reports on the results of the plan sent up the previous sol, and where the plan for the next sol is officially handed over from the science team to the uplink team) the TEGA team lead reported that the first command to shake didn’t complete, and they got an abort – because the oven was full! And while we all clapped and cheered, he proceeded to play “(Shake Shake Shake) Shake Your Booty” on his computer and dance (you can see a picture of him, not dancing, at http://phoenix.lpl.arizona.edu/boyntonWilliam.php). There were a number of “did the ground move for you?” jokes, and after the meeting the TEGA team members opened up some champagne in their downlink room – and well deserved, as they just went through a number of intense days full of troubleshooting and brainstorming.
In today’s plan, we are delivering our first real sample to the Optical Microscope and taking pictures under several different light sources (provided by LEDs at different wavelengths). We had an intense discussion on whether or not it is safe to sprinkle a sample onto the Optical Microscope while the big stereo imager (SSI) is looking at MECA – what is the probability that dirt will get picked up by the wind and blown into the lenses? When we did the sprinkle test, we had the SSI go into “stow” position looking straight down to avoid the possibility, but the team forgot that change, and it was noticed too late in the sequencing process to change it. We looked at the height of the scoop, the direction that the wind has been at that time in previous sols, and got the go-ahead from the science team, so we ‘re proceeding with the plan and making a note that in the future we ought to stow.
While I’m off-duty, we will be telling TEGA to go ahead and bake the material in the oven. Now that TEGA has its first sample, we are officially in science operations – a fact that got a rousing cheer from the team today.
The fourth day on-shift has been consistently the hardest for me to stay alert, as my work day starts already 2 hours later than my first. The uplink room is kept very cold, and it is a little surreal to be wearing a sweater while it is over 100˚F outside. On the other hand, the temperature at the Phoenix lander as of a few sols ago was high of -32˚C, low of -80˚C, or -26˚F and -112˚F.
And finally, I want to mention that apparently there is a special program on Phoenix tonight (Wednesday) on The Discovery Channel. You won’t see me, because cameras are not allowed in the uplink room, but you should be able to find out more about the long process required before we ever got to Mars. Time for some tea, an asprin, and relaxation.
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