Blogs / Cosmic Variance

Last week Geoff Brumfield reported in Nature about possible delays to the upcoming Hubble Space Telescope servicing mission (”SM4″) due to the recent satellite collision. Naturally, those of us who know and love Hubble were a tad concerned about this latest development, which would probably have led to a complete shutdown of the telescope in a year or two. Hubble is currently the equivalent of a 1969 VW Beetle that’s scheduled for an upcoming episode of “Pimp My Ride” — it gets around town just fine at the moment, but we hope it keeps long running long enough to be tricked out during SM4.

The latest news (or latest to me, since I just got a hold of the memo, which is actually about a week old), is that they’re cautiously optomistic that the servicing mission will be able to go ahead. The key points given in the “settle down y’all” memo are:

• NASA is proceeding with plans for the STS-125 (SM4) servicing mission to the Hubble Space Telescope in May 2009. A safety and mission assurance review for SM4 is scheduled for April. An in-depth analysis of all the risks, including the potential orbital debris risk – something assessed before every mission – will be considered at that time. NASA also will further assess debris risk at the mission’s flight readiness review, held routinely before each shuttle launch.
• The Hubble servicing mission team is confident the debris risk will be acceptable for the flight, but it requires time for proper analysis. Currently, the team does not have an updated risk assessment for the STS-125 mission that includes the satellite collision on Feb. 10. A detailed analysis will be available in mid-March to develop mitigating strategies, such as alternating attitudes or adjustments to the planned spacewalks.
• As NASA orbital debris experts continue to better define the risks to our spacecraft resulting from the collision, the Hubble servicing mission team will evaluate any potential additional risk caused by the collision.

The other good news, assuming that the servicing mission goes, is that the astronauts are doing really well at speeding up the installation and/or repair of the new and refurbished instruments. In terms of instruments, the servicing mission’s priorities are to install COS and WFC3, and, if there’s time, to repair STIS and ACS. However, the repairs are limited by the numbers of EVA’s (extravehicular activities) and their duration. Thus, the faster the repairs can go, the higher the chance that all 4 instruments will be up and running by the end of the mission. The key to getting them all in is whether ACS can be repaired in one EVA, or split over two. If it’s the latter, then there’s lots of packing and unpacking that has to be done at the beginning and end of each EVA, which adds a lot of overhead that could be spent actually fixing stuff. The word is that John Grunsfeld (astronaut, astrophysicist, and veteran of previous servicing missions) is getting positively speedy at the repairs. Moreover, he’s rumored to have a metabolism that doesn’t burn much oxygen, which means he can stay out on an EVA longer that mere mortals — kind of like Lance Armstrong, but in space. This means he can probably fix ACS in one shot, which will help them get ahead of schedule. So, if the mission goes in May as expected, the news from Hubble could be terrific.