A major repair to the Hubble Space Telescope 10 years ago this week is still helping us uncover the history of the universe. However, as described in a new video from NASA, the 2009 launch of space shuttle mission STS-125 to the famed observatory almost never happened.
Space shuttle Atlantis, the video explains, sent two new instruments in orbit for Hubble, and tools to repair two more instruments on the telescope. The upgrade allowed Hubble to better peer at the youngest stars and galaxies, and to learn how galaxies formed. On top of the successful repair, NASA got a public relations boost when astronaut Mike Massimino sent the first tweet from space.
Yet six years before, this mission was canceled. NASA reviewed all of its mission plans after the space shuttle Columbia broke up during reentry on Feb. 1, 2003, killing all seven astronauts on board. The agency had planned a final repair mission for Hubble after four successful astronaut visits — but NASA administrator Sean O'Keefe decided it was too risky to go ahead. NASA officials were considering sending robots to do the repairs instead, according to a statement from the agency.
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Robots or humans?
However, Hubble — which launched in 1990 — needed help quickly to continue observations. Three of its aging six gyroscopes (which are used to point the telescope precisely at space targets) didn't function any more. A spectrograph failed completely in 2004. At one point, Hubble was unable to do any science for a month, according to the statement.
NASA worked diligently on plans to send robots to Hubble in an effort led by Frank Cepollina, who at the time was associate director for NASA's Satellite Servicing Capabilities Project. Amid public protest and scientific concern, however, NASA changed its mind on Oct. 31, 2006, when new administrator Michael Griffin (after reviewing the situation carefully with senior agency officials) said a space shuttle mission could be conducted. NASA took several extra safety precautions to reduce the risk to the STS-125 crew, including having a backup space shuttle and crew ready to launch if a problem befell the orbiting astronauts.
Cepollina's team continued to work on repair procedures, this time for astronauts. During their work, a second instrument — the Advanced Camera for Surveys — also failed. Past missions generally instructed astronauts to replace failed equipment, but technology had advanced a lot since the 1990s. The group decided that tools had progressed far enough in development so that astronauts could do tricky repairs on this expensive instrument (worth hundreds of millions of dollars), rather than replacing it.
Launch was set for October 2008 until yet another Hubble failure messed up those plans. The telescope's Science Instrument Control and Data Handling unit experienced an anomaly. This was a serious issue, because this unit is responsible for formatting scientific data that Hubble collects, and also for managing the science instruments.
NASA delayed the launch and found a spare unit inside a simulator at the Goddard Space Flight Center. Testing it for flight took six months. Once engineers knew the unit was safe to go to space, STS-125 had a new launch date. The astronauts launched safely on the space shuttle Atlantis on May 11, 2009.
The repair job wasn't easy. In a recent quote in the NASA statement, Massimino remembered a moment when he was taking out handrail screws on top of the Space Telescope Imaging Spectrograph (STIS) instrument panel. STIS needed a new power supply, and Massimino had it ready. However, while three screws came out with no issues, the fourth stripped underneath his drill.
"I saw what I had done and my heart just sank," Massimino said. "I quickly did the deduction ... if that screw doesn't come off, the handrail doesn't come off, and then 111 screws don't come off the panel. That means the power supply doesn't come out; a new one doesn't go back in, and STIS doesn't come back to life. We'll never find out if there's life in the universe, and everyone's going to blame me."
NASA ground control and the orbiting astronauts troubleshooted the sticky screw for 4 hours, including using different drill bits to loosen it. When nothing worked, NASA instructed Massimino to rip the handle off — while being careful not to let any of the jagged edges puncture his suit. Massimino carefully pulled at the handle, and to everyone's relief, it came off with no further issue.
The historic repair means that the telescope is still going strong today, after an incredible 29 years in space. (In October 2018, Hubble experienced a major gyroscope issue, but it resumed operations; the telescope also had camera glitches in 2019.) Its many achievements include helping to show that the universe's expansion is accelerating; doing reconnaissance shots for the New Horizons mission before the spacecraft's Jan. 1, 2019, flyby of the distant object MU69, nicknamed Ultima Thule; and examining areas with dark matter — a mysterious substance that makes up most of the universe's mass, but whose composition isn't pinned down yet.
"We still have full redundancy in all of the spacecraft's critical systems," Larry Dunham, Hubble's chief systems engineer at NASA's Goddard, said in the statement. "It's just unbelievable that we're still going today."
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Follow Elizabeth Howell on Twitter @howellspace. Follow us on Twitter @Spacedotcom and on Facebook.