Origins Hubble a view to the edge of space  
spacer people ideas tools place spacer

Hubble Live

Hubble Revisited
by Mary K. Miller

Last spring, an Exploratorium Webcast team took you on a tour of the Hubble Space Telescope . We went behind the scenes at the Space Telescope Science Institute in Baltimore, and peered over the shoulders of scientists and image specialists as they focused the space telescope on objects in deep space and created amazing images of the Horsehead Nebulae. We also got a look at space hardware destined for Hubble during a live Webcast inside the giant clean room at NASA's Goddard Space Flight Center in Greenbelt, Maryland.

Now, astronauts, aerospace engineers, and space shuttle flight controllers are getting ready to launch the fourth servicing mission to Hubble to exchange some worn-out parts and place a powerful new camera on the twelve-year-old space telescope. On March 1, 2002, the space shuttle Columbia will blast off the pad at Kennedy Space Center and dock with Hubble 360 miles above earth. Two teams of astronauts will spend five days of space walks (known as Extra Vehicular Activity or EVAs) repairing and improving the vision of one of astronomy's most important telescopes. From liftoff through the last EVA, the Exploratorium Webcast team will take you along on the mission and introduce you to scientists who are anxiously awaiting the new, improved Hubble and what it will tell us about the structure of deep space and the origins of the universe.

Space Shuttle Columbia
The Space Shuttle Columbia

Getting Ready to Fly

The NBL pool
Neutral Buoyancy Lab
Preparing for this shuttle mission, known as Hubble Servicing Mission 3B, has been a two-year process of prepping new instruments and space hardware for flight, and training space-walking astronauts in one of most complex and technically challenging servicing missions to date. Some of the Hubble instruments were not originally designed to be replaced, so special tools were developed. Astronauts went through months of training for each task, including hundreds of hours in the "tank," or Neutral Buoyancy Lab (NBL), at Johnson Space Center in Houston.

The NBL is a six-million-gallon pool, 100-by-200-feet wide and 40-feet deep, that contains full-scale models of the space telescope on one end, and the pods of the International Space Station on the other. Being underwater is about the closest way of simulating space walks on earth, so astronauts use the NBL to practice handling new tools and learning the steps involved in each task they'll perform in space. It's a laborious process. First, they don their space suits and are lowered by crane into the pool. Once in the water, scuba divers tend to them, filming their every move and staying close in case equipment fails and the astronauts need assistance.

John Grunsfeld interview
Exploratorium crew interviews
astronaut John Grunsfeld
The Exploratorium team caught up with the astronauts training at NBL last summer and talked with Astrophysicist and Shuttle Payload Commander John Grunsfeld (we'll show our interview with Dr. Grunsfeld on the second Webcast scheduled for March 2). This will be Dr. Grunsfeld's second visit to Hubble; he was also on hand for the emergency servicing mission in December 1999 to replace failed gyroscopes that had stopped pointing the telescope properly.

"For every hour we spend in space, we'll practice 10 to 12 hours in the pool," Grunsfeld says. "These are very highly choreographed tasks, like a ballet where you have to know every move ahead of time. The amazing thing about our training here is that when you get to space, although the feel and the look of it is very different, training your motor skills is very similar."

As a working astronomer, John Grunsfeld especially appreciates his experiences visiting Hubble in space and helping to keep this valuable tool working at its peak performance. "To me, it's an absolute dream to go work on the Hubble Space Telescope, "he says. "I was awestruck. It's so beautiful, and to be able to reach out and touch the telescope was really like a dream."

In addition to their pool work, astronauts also spend time preparing for the mission in the shuttle mock-ups at Johnson. Full-scale replicas of the shuttle - both in its launch (nose up) and flight configurations (horizontal) - help the astronauts get used to the tight quarters and the equipment they'll work with during launch and flight operations inside the space shuttle. In the months preceding the servicing mission, the team also visited Goddard, where they got a close-up look at the hardware that will go up with them to Hubble.

Giving Hubble New Sight

All that training is in preparation for the big space show that begins on March 1. It starts with the launch, scheduled for 6:38 a.m. Eastern time. Staff Physicist and Webcast Co-host Ron Hipschman will be on hand for liftoff. On the first Webcast, which airs March 2, he'll relate what it's like to be near the launch pad and what he learned about the operations at Kennedy Space Center in Florida.

Mission control
Mission control in Houston
After the launch, ground operations take over at the Johnson Space Center in Houston. There in the control room, nineteen teams of engineers, flight controllers, flight surgeons, communications specialists, and others track, advise, and control operations in space. It will take the space shuttle Columbia a few days to rendezvous with Hubble and come to a near crawl in relation to the telescope. On flight day 3, Flight Engineer Nancy Currie will use the shuttle's robotic arm to grapple the telescope into the shuttle bay and retract the telescope's solar panel "wings" in preparation for replacing them with more compact and powerful solar panels.

EVAs start on flight day 4, when payload commander Grunsfeld, together with veteran astronauts Jim Newman and Rick Linnehan and space rookie Mike Massimino, will take two days to replace the solar arrays and prepare for a changeout of the power control unit. According to Houston Flight Director Bryan Austin, the third EVA, on flight day 6, will be the most challenging. That's when the old power control unit will be removed and replaced with a new one. This is hardware that wasn't originally designed to be replaced and has thirty-six closely spaced and delicate connectors. It's likely to take the entire day, and ground controllers will have to watch carefully to make sure the astronauts don't use up all their battery power and oxygen.

EVA 4 is the day that scientists are most excited about. That's when the Advanced Camera for Surveys (ACS), a telephone-booth-sized instrument, will be placed into the telescope, allowing for many more opportunities for discovery. The camera will increase Hubble's vision into deep space ten-fold, will provide two times the observational area, two times the resolution, and four times the sensitivity than the camera it's replacing. The designers of the advanced camera think it may even be powerful enough to take an image of planets in other nearby solar systems.

On the last day of planned space walks, EVA 5 (flight day 8) astronauts will replace a cooling system to restore the infrared vision of Hubble. Once they close up the telescope, they'll give it a boost to a new, higher altitude and release Hubble back into space.

Future of Hubble

After the astronauts have given the space telescope its send-off and returned to earth, telescope operations will resume at the Space Telescope Science Institute in Baltimore. About three weeks after the mission, Hubble will start collecting science observations again and the advanced camera will take its first test pictures. With ACS, astronomers will be able to look in the gaps around bright stars for clumps of dust and gas that may be early signs of planet formation. The new instrument will also be useful for astronomers who study quasars, powerful distant objects in the farthest reaches of the universe that are thought to be highly active black holes in the center of galaxies.



Origins:Exploratorium:Hubble Origins home Exploratorium home page Hubble home page

© Exploratorium
Hubble home page