Archive for May, 2009

Eyewitness reports from the final Hubble Space Telescope Mission

On Monday, May 18, Astronauts John Grunsfeld and Drew Feustel began the final spacewalk an hour ahead of schedule, determined to see all repairs were completed; including on which had been delayed by difficulties with a stubborn screw the day before. Dr. Ed Cheung, Principle Engineer of the Hubble Service Project, normally working out of Goddard Space Center, had been stationed at Kennedy Space Center with his team for months prior to launch and after at Johnson Space Center walking the astronauts through the practice for and actual repairs. He has been sending his daily eyewitness reports back to his native island of Aruba to share this great adventure with his countrymen. Dr. Cheung confirms this final Extra-Vehicular Activity, EVA 5 completed the required repairs and installation of new equipment, and the Atlantis crew will be heading home. A misstep by Astronaut Grunsfeld resulted in small piece of the HST antennae breaking away, but scientists on the ground report no disruption in communications with the science platform.
Dr. Cheung writes: “Today is the last EVA day. We installed a new Fine Guidance Sensor (FGS), the second new battery, and several door blankets (NOBLs.) I was not involved in the development of this equipment.”

“The FGS is used to lock Hubble onto a target.  Whenever a science observation is scheduled, two guide stars are selected near the target.  These are bright single stars with known locations.  When Hubble is moved to acquire a target, it looks for those bright stars, and ‘locks onto’ them.  It then directs its attitude control system to keep those stars in precise view.  If they should appear to move, the control system moves the vehicle to keep them in the same spot.  This is one of the reasons Hubble is so stable.  There are three FGS’s on Hubble, and two have been replaced (one is still original).  Installation of the new unit encountered the same problem as WFC3: the old bolt did not want to release (seems to be a common problem), but it was handled the same way, and no further problems occurred.  The new one passed all tests”

“The NOBLs are new blankets for the small doors on Hubble.  The old insulation has deteriorated due to so many years of sun exposure, and this impacts the electronics inside.  One of these doors holds the data transmitter to the ground.  If this overheats, we would have a big problem.  Currently, we manage this by turning the transmitter on and off.  With all the new instruments, it would be a shame not to get the images down to the ground, so a new blanket was essential.  Our lead spacewalker, John Grunsfeld, knows this, and you could tell in last night’s conference with the Flight Director, how driven he was to install all three NOBLs.  We felt great when hearing the determination in his voice.”

“To cut to the ending….today’s space walk went extremely well.  It took John and Drew only 4 1/2 hrs to finish the two main tasks.  They were then able to install all three new blankets.  We had always planned on installing only one this day.  But their hard work allowed us to do all three.  After doing all this to benefit to Hubble, John had a small accident just prior to coming back inside.  He knocked the very tip off the communications antenna; this is underneath Hubble.  This was no big deal, but they installed a protective cover that was onboard just for this eventuality.  While John was coming back in, he said “Sorry Mr. Hubble”.  I get emotional just thinking about this.  He has done so much for Hubble, and I hope he won’t beat himself up over this.  We all know how much Hubble means to John, being the only astronomer-astronaut to work on her.”

“Tonight we had a few short social events in our control room at mission control.  The wives of some of the astronaut crew came in and presented us with a cake in the shape of Hubble.  It was nice sharing it with them.  “I won’t miss the long hours or travel away from home. However, I will miss coming to work and seeing the Shuttle everyday on the drive in; the excitement I felt these past few months and during my time at Kennedy Space Center; having the security clearance to be able to go into the Orbiter any time I wanted to; having lunch or dinner with my work buddies every day; the quiet times at Mission Control when I can write these notes; the busy times at Mission Control when I am trying to solve 2 or 3 problems simultaneously while listening to the loops.”

“Tomorrow we will release Hubble, and say goodbye to her for the last time.  I will probably stay an extra long shift to witness it.  With that, this will be my final update of STS-125.  I have enjoyed writing them for you, and I really hope you have enjoyed reading them.  I am pretty tired of these shifts, and ready to go home, but I know that after a few days there, I will look back at this whole mission, and realize how much I wish I could do it again.”

Continued eyewitness coverage of the final mission to completely overhaul and update the Hubble Space Telescope continues to stream in from Dr. Ed Cheung, Principle Engineer of the Hubble Service Project, who was born and raised in Aruba.

Sunday’s spacewalk, EVA 4, was performed by astronauts Mike Massimino and Michael “Bueno” Good. The walk took an additional 2 hours longer than the original 6 ½ hours planned. The goal was to repair one of two redundant channels in the Space Telescope Imaging Spectrograph (STIS), a state-of-the-art instrument that broke down in 2004 when its low-voltage power supply failed. Removal of a handrail blocking access held up the work. Three bolts holding the central bar of the handrail unscrewed easily, but the forth was stripped by attempts at removal. The final solution was the use of brute force, as Astronaut Massimo pulled the handrail away once the anticipated breaking points were protected with tape to prevent debris from flying about. The time wasted forced the astronauts to return to the shuttle to top off their air supply and recharge the batteries on their power tools to be able to continue with the purpose of EVA 4.
Dr. Cheung’s latest update on Sunday’s events:

“Today we performed the repair of the STIS.  I did not work on this hardware.  We were also intending to install a replacement shell on one of the small doors.  These are called NOBLs (“nobels”). When we repaired ACS, it included the removal of 32 little screws.  Today, we repaired STIS, which required the removal of 111 screws of three types!  Doing these repairs were considered a crazy idea when these instruments failed, but we gradually found that “yes” we can do this little job, then that little job, and before you knew it, we realized we could do the whole thing.”

“However, before we could get to the lid, we had to remove a handle bar on the outside shell of the instrument.  Recall that this science instrument was never intended to be repaired in space.  Well, the crew removed three of the four screws, but….the fourth one was damaged and would not turn!  After one and a half hours of various attempts at removal, the crew considered just pulling the bar off, and breaking the screw.  By then, several of our colleagues had replicated this condition on the ground in one of our machine shops and found that it took 60 lbs of pull force to snap the bolt by pulling the long handle.  Here in Houston, we saw the video of the team doing this back home in Maryland, and the spectacular result of the bar flying around the machine shop once it was loose.  We all wondered if crew safety would allow us to perform this procedure in space.”

“We had Mike Massimino doing the task (nicknamed “Mass”).  He is a very tall and strong guy, so he was up to it.  Unfortunately, we did not have a video link, so we never got the video.  He pulled the handle off, and we were able to proceed.  That was another one of those unbelievable moments of this mission were they just did what had to be done.  He then placed a special plate on top of the cover of the instrument.  This plate is extra thick with little Lexan compartments.  A thin tool can be used to loosen the screws of the lid, but they would be captured in this Lexan shell.”

“Once all those screws and the lid was removed, Mass brought it close to his helmet camera, and it was breathtaking to see all those tiny screws and washers floating around in each of their little Lexan cells.  They looked like little fish swimming around in their little bowls.  Ordinarily such a sight in space would be a nightmare were it not for them being contained.  One of my coworkers describes it best.  He said that they looked like a bunch of angry bees.  OMG, if they ever got out!”

“In a previous update, I described the voice ‘loops’ that we use to communicate with each other.  The most exclusive of these is A/G, or Air-to-Ground.  This is what Houston uses to talk to the crew in space.  The only person that is normally permitted to talk from the ground is called “Capcom” (captain of communications).  This person is always an astronaut.  He represents the crew’s interest on the ground, and he sits right next to the Flight Director (“Flight” from Apollo 13).  Any of us is allowed to listen to monitor this loop.  Well tonight, we were privy to an unusual event.  Flight talked directly to the astronaut crew in a strategy session for tomorrow, the final space walk day at Hubble.  It was a very candid talk, and we felt the great relationship they have with each other.”

“So far, all of our space walks have been very successful.  It is a testament to my coworkers that all the hardware has electrically and mechanically fit and functioned without problems.  Of course, the astronaut crew deserves credit too, but there are thousands of unseen people on the ground that designed, built, tested and prepared the hardware over the course of years to get to this point.  We now have two amazing imaging instruments, half a set of new batteries, new gyros, a new spectrograph, and other smaller items installed and tested.  Soon (tonight) we will find out about the second spectrograph repaired today.  Hubble is already the most powerful it has ever, ever been, and we have one more day to go.”
As equipment is installed and repaired, the Hubble team at Goddard Space Center in Maryland begins running tests to insure all is working properly before the shuttle departs the HST for good. One more day of repairs, with no more missions to HST planned, as a new telescope platform is already designed to eventually replace Hubble. Astronauts’ lives are at stake every day in space, a calculated risk, but one NASA does take arbitrarily. Turing the final day of STS-125, they must be sure they have successfully accomplished all they set out to do to insure HST is performing at top efficiently while delivering high quality information to scientists exploring our universe.

Eyewitness accounts of the final service mission to the Hubble Space Telescope

Servicing Mission (SM 4) is now four days done, and astronauts John Grunsfeld and Andrew Feustel have completed the first of five space walks to service and upgrade the Hubble Space Telescope 350 miles above the earth. The two priority jobs, replacement of the science computer and installation of the Wide Field Camera 3 (WFC3) are now completed. The removal of the WFC2, which served scientists for sixteen years and provided some remarkable images, proved not so simple a task as anticipated.

Dr. Ed Cheung, born in Aruba, holds the position of Principle Engineer of the Hubble Space Telescope Service Project, and was the designer of the WFC3, which he spent eight years perfecting. In his latest daily update from mission control at Johnson Space Center in Houston, Texas, he explains that a long day of unexpected difficulties made the tasks of installing these two vital pieces of equipment as “harrowing.”

“Today we had our first day with space walks.  EVA Day 1 (Extra-Vehicular Activity Day 1).  On this day, we installed the WFC3 and SIC&DH. It will be the next premier imaging instrument for Hubble.  Compared to the one it is replacing (which has only about 2.5 Megapixels), the new camera will have 16 Megapixels.  More importantly, it can see a wider range of colors, from infrared to ultraviolet.  It will be like opening our eyes for the first time to colors and details we have never seen.”

“The SIC&DH is the science data computer that failed last year, and caused the delay in the mission.  At the time, we switched to the backup unit that had been in space for 18 years waiting for its turn.  However, NASA management decided we would not risk another failure that would render Hubble completely useless as a science instrument.  I happen to be Electrical Lead on both of these items, and they were on the first EVA day due to their priority.  WFC3 was first.  Well, it did not go smoothly.  We had major problems getting the old instrument (WFPC2) out.  To remove the instrument, the astronauts needed to turn one bolt.  Well it did not turn at all!  They had to change tools to apply more and more torque.  It got to the point where they could snap the bolt in half by applying more than 50 ft-lbs of torque.  If that occurred, we would never be able to remove the old instrument to put in the new one.  This was extremely harrowing (to say the least).”

“Due to my shift schedule, I watched this all unfold in my hotel room.  I had access to the live TV from space, and communicated with my teammates via a chat program.  While this was all unfolding, we were all getting very anxious, including me.  When all options were exhausted, and the astronaut approached with the big wrench, we were all hoping for the best.  When Drew Fuestel finally turned the bolt, and it turned, we did not know if the bolt broke or not.  He then reported to our relief that he said that it felt like it was turning, and not broken!  There was applause in the control rooms back home in Maryland and in Texas.  Prior to that, I could not believe that this was happening.  After years of work, and careful planning, a single bolt almost caused it all to go to waste.  So far, our tests of the new camera are good.  The tests will continue through the night.”

The WFC3 should soon start delivering remarkable images of space never observed by scientists before. Literally, the camera is a “time machine,” as the images will be from celestial bodies so distant that scientists will be watching events that have taken places centuries and millennia past, because of the time it takes for light to travel to the Hubble. More space walks and repairs continue today, with the hope that all goes smoothly, but prepared for perhaps another “harrowing” day.

Story by Rosalie Klein