July 01, 2002


 NASA veterinarian treats Hubble Space Telescope

Posted June 15, 2002
Space Walk

On the last day of April, extraordinary pictures from deep space dazzled newspaper readers, television audiences, and Internet visitors. NASA had just released the first images from the Hubble Space Telescope since its servicing in March.

The stellar beauty and stunning clarity of the pictures were what initially captivated viewers—the scenes of colliding galaxies and brilliant, gaseous nebulae.

An even deeper amazement set in when they came to understand what it was they were witnessing—the closest thing to time travel: snapshots of events that had transpired hundreds of millions of years ago.

Release of the Hubble photos was a poignant occasion for veterinarian Richard M. Linnehan of the NASA astronaut corps. He was a member of the STS-109 crew that serviced Hubble during the March 1-12 space shuttle Columbia mission.

Dr. Linnehan said that even though the crew thought they did everything right when they replaced Hubble's Faint Object Camera with the Advanced Camera for Surveys, they didn't know for sure whether the mission was a success until Hubble began transmitting pictures several weeks later. The ACS is composed of three cameras with ranges from visible to far ultraviolet wavelengths.

"You do no harm and maybe do some good, and on this particular mission, we did a lot of good because everything we put in worked," he said triumphantly.

"We upgraded the systems, and the pictures came back beautiful. That camera sees 10 times farther than the old camera did, with 10 times better resolution. Those are only the beginning of what we are going to see."

Anticipation is building for pictures from another Hubble camera. The STS-109 crew installed an experimental refrigeration unit on Hubble's Near-Infrared Camera and Multi-Object Spectrometer. The previous cooling system was a block of cryogenic nitrogen that had sublimated away, shutting down the NICMOS camera. The first photos were expected in June.

"The visible light spectrum is a very small band," Dr. Linnehan noted. "There's a whole lot going on in the infrared wavelengths that is invisible to the human eye. The NICMOS will be able to image that part of the spectrum."

One of the striking images transmitted by the ACS is a collision between two galaxies called The Mice, as they resemble two mice with tails that are actually long "streamers" of what appear to be stars, caused by the gravitational forces at work in reshaping the galaxies postcollision.

"It's like being in a time machine," Dr. Linnehan said. "In those images, you're seeing things that happened hundreds of millions to billions of years ago—at the very beginnings of the universe itself. In some cases we're looking at light that left other galaxies more than 13 billion years ago. We can only theorize what they look like now."

Another astonishing reality: "In the new pictures of The Mice and Tadpole galaxies, all those pinpoints of light surrounding the galaxies are not stars, but more galaxies! They are so distant that they appear to be individual stars, but each of these pinpoints of light contains hundreds of billions of their own stars. It boggles the mind."

Dr. Linnehan teamed up with astronaut John Grunsfeld on three of the mission's five space walks for a total of almost 22 hours in space. On March 4 they replaced one of Hubble's solar arrays, on March 6 they replaced the main power control unit, and on March 8, they installed the experimental cooling system on NICMOS.

"Surreal" is the word Dr. Linnehan uses to describe the space walks. Stargazing is a luxury when extravehicular time is so compressed and work on the precious instruments so intense. But he did catch sight of Africa, South America, and Australia while at work.

Encountering the unexpected is expected. "You train with backup procedures and contingencies, so that you know what to do three or four failures deep," he explained.

As the Space Shuttle Columbia approaches the Hubble Space Telescope, Dr. Linnehan uses a laser-ranging device to measure the range between the two spacecraft.

Dr. Linnehan trained about two years for this mission. Rehearsals for the space walks, known as extravehicular activities or EVA, occurred underwater in a giant pool called the Neutral Buoyancy Laboratory on a full-scale Hubble mock-up. The same suits used in space are adapted for underwater training in the NBL to simulate the space environment. Except for the difference between water viscosity and the vacuum of space, the NBL closely simulates the free fall of microgravity. For every hour spent on Hubble in space, the crew trained about 12 hours underwater.

Dr. Linnehan and the pilot were the mission medics, trained in simple procedures such as injections and suturing. If a medical emergency arose, the crew would deorbit.

This was Dr. Linnehan's third mission aboard Columbia, and he has logged more than 43 days in space. In 1998 he was the payload commander on the STS-90 Neurolab mission, a life sciences mission that studied the brain and its basic neurophysiology in the microgravity environment of space and how these physiologic processes mimicked certain disease processes in human populations here on earth. In 1996 he was a mission specialist on STS-78, the Life Sciences and Microgravity Spacelab mission, where he studied similar effects of space travel on bone and muscle physiology.

What does he think his veterinary colleagues would most like to know about his work? "Just what it's like being in space, in a microgravity environment, and getting a chance to work on something unrelated to veterinary medicine, which, at the same time draws from a lot of the skills, training, and education we got while in veterinary school."