Atlantis to reach the Hubble Space Telescope today
BY WILLIAM HARWOOD
STORY WRITTEN FOR CBS NEWS "SPACE PLACE" & USED WITH PERMISSION
Posted: May 13, 2009
In the final stages of a complex rendezvous, the shuttle Atlantis closed in on the Hubble Space Telescope early Wednesday, on track for a robot arm capture that will set the stage for a challenging five-spacewalk service call. Astronaut Megan McArthur, operating the shuttle's 50-foot-long space crane, plans to grapple the telescope around 12:54 p.m. and then mount it on a service platform at the back of Atlantis' payload bay.
The terminal phase of the rendezvous begins at 10:41 a.m. with a critical rocket firing designed to close the final few miles between the shuttle and the bus-size space telescope. Commander Scott Altman, flying Atlantis from the ship's aft flight deck, plans to approach the observatory from below, matching velocities as the two spacecraft steak 340 miles above the north coast of Madagascar at 5 miles per second (interested readers and check on the location of the shuttle and Hubble with GoogleSatTrack at: http://www.lizard-tail.com/isana/tracking/)
"Rendezvousing with Hubble is a little different than going to space station," Altman said in a NASA interview. "Obviously, it's in a different orbit, but it's also a small target compared to how big station has gotten, and it doesn't help us out as much during the rendezvous in that station has a little system that gives it range and range rate as you get close. Hubble is just passive, it's sitting there, it doesn't have reflectors. So we're using a little handheld laser, which is kind of like a police radar gun that you would see on the side of the road, to get the distance and the closing rate as we're coming up to Hubble. We're doing it basically by hand."
In the final phases of the approach, "I'm looking out the window, watching Hubble, and then listening to the calls that my other operators are making by using that laser range finder about how close we are and how fast we're going to know what input to make as we get close to it. So I think it's a more challenging rendezvous than having as much information as the station guys have."
This is Altman's second Hubble visit in a row and "at one point last mission we talked about putting a reflector on Hubble to make it easier for the next guy, but I thought, well, you know, it was hard for me; let it be as hard for the next guy. Now it turns out I am the next guy so I realize that was shortsighted of me!
Once Atlantis closes to within a few feet of Hubble, Altman will fly in formation with the telescope to give McArthur a stable target.
"If I've done my part well and flown up to Hubble gracefully, I can stop and I say, OK, I'm going to go to free drift, which means I'm not making any more inputs, and that we'll stay close together without much motion to make it easier for her to reach out and grab it. We also train to grab it if it's moving a little bit but my job is to make it as stable and easy as possible for the arm operator to go out and get."
McArthur, making her first space flight, said she doesn't anticipate any problems.
"As soon as we're comfortable that the orbiter's rate has been matched to the telescope and the telescope looks to me like it's stable and not moving, then I take the robotic arm, the shuttle's robotic arm, and I reach out and grab the telescope," she said in a NASA interview. "There is a grapple fixture, a pin, basically, on the side of the telescope, that we use. The robotic arm grabs onto that. Once we have a good capture of the telescope, I then maneuver the robotic arm, to install the telescope into a berthing mechanism at the back end of the shuttle payload bay. And once we have installed the telescope in that berthing mechanism, we latch it down and I can release the shuttle's robotic arm."
Hubble will be mounted on a rotating service platform that can position the telescope as required for servicing. A detailed photo survey will be carried out shortly after capture to document the condition of Hubble's exterior and its aging insulation and an electrical cable will be remotely plugged to provide shuttle power for the duration of the service call.
Engineers are anxious to get a good look at Hubble's insulation to find out how it may have degraded over the seven years since the last shuttle visit in 2002.
"When we arrive, I expect it not to look a lot different than it did on STS-109 (in 2002), but I do expect that ... some of the multi-layer insulation on the outside of the telescope will be peeled back a little bit more," lead spacewalker John Grunsfeld, making his third visit to Hubble, said before launch.
"The environment where Hubble is is pretty severe, the temperature extremes, atomic oxygen, the solar ultraviolet, all those nasty things in space are what is causing the telescope (exterior) to degrade. It's somewhat expected. Hubble has been in space for (19) years, it's pretty remarkable it's doing as well as it has. What I remember so vividly from the last missions is that once you open up the inside of the telescope, it looks absolutely brand new. We expect that to be the case as well."
The astronauts will review spacewalk procedures late this afternoon before going to bed at 8:31 p.m. Grunsfeld and Andrew Feustel plan to begin the mission's first EVA at 8:16 a.m. Thursday.
Here is an updated timeline of today's activity (in EDT and mission elapsed time; includes revision B of the NASA television schedule):
EDT........DD...HH...MM...EVENT 05/13/09 05:01 AM...01...15...00...Crew wakeup 06:16 AM...01...16...15...HST: High gain antenna retraction 07:26 AM...01...17...25...Group B computer powerup 07:41 AM...01...17...40...Rendezvous operations timeline begins 08:11 AM...01...18...10...Middeck preps 08:41 AM...01...18...40...EVA-1; Tools configured 08:51 AM...01...18...50...HST: Solar arrays slewed to 90 degrees 09:02 AM...01...19...01...NC-4 rendezvous rocket firing 10:41 AM...01...20...40...TI rendezvous rocket firing 12:01 PM...01...22...00...HST: Move to capture attitude 12:54 PM...01...22...53...HST capture 01:46 PM...01...23...45...HST berthing 02:01 PM...02...00...00...HST survey 02:16 PM...02...00...15...External power on 02:46 PM...02...00...45...Group B power down 03:56 PM...02...01...55...Shuttle robot arm (SRMS) park 04:00 PM...02...01...59...Mission status briefing on NTV 04:21 PM...02...02...20...HST: Solar arrays slewed to 0 degrees 04:41 PM...02...02...40...EVA-1: Procedures review 05:41 PM...02...03...40...HDTV downlink 08:31 PM...02...06...30...Crew sleep begins 08:31 PM...02...06...30...HST: KU-band checkout 08:45 PM...02...06...44...Space telescope update 09:00 PM...02...06...59...Daily video highlights reel on NTV 10:01 PM...02...08...00...HST: Engineering data playback