NASA astronauts upgrade Hubble with cameras designed at Hopkins

On Friday Mar. 1, 2002, the Shuttle Columbia blasted off from Cape Canaveral, Fla., destined to service and repair the Hubble Space Telescope in one of the most complex repair missions to date. The crew, composed of mission commander Scott Altman, mission specialist Rick Linnehan, pilot Duane Carey, robotic arm operator Nancy Currie and spacewalkers John Grunsfeld, James Newman and Michael Massimino, will be the fourth servicing crew sent up to repair the nearly 12 year old telescope.

The mission the astronaut have been sent into orbit to perform is analogous to complicated surgery according to Dr. Linnehan, "think of (Hubble) as a big old beast and I'm doing surgery on it? the one cardinal rule about surgery is you don't want to make it worse?.You want to make sure everything works at least as well as it did before you went in, and hopefully a lot better."

With that in mind, the crew will not only be making repairs on the multi-billion dollar telescope, but improving it as well with the installation of a brand new instrument.

The device, know as the Advanced Camera for Surveys or ACS, "will increase the discovery efficiency of the (Hubble Space Telescope) by a factor of 10" according to official website.

The camera was developed at Johns Hopkins under the direction of Dr. Holland Ford, the principal investigator. The refrigerator-sized ACS will be replacing the telescope's Faint Object Camera. The ACS is made up of three electronic cameras as well as several filters and dispersers. It is capable of detecting light in the range from ultraviolet to near infrared (1200 - 10,000 angstroms). According to the design team the $75 million camera is so powerful that it would be able to distinguish between two fireflies six feet apart in Tokyo, even if it was set up in Washington, D.C.

Essentially Dr. Ford describes it as "a Cadillac compared to a Volkswagon."

However, the installation of this critical device won't occur until the fourth of five spacewalks. After the Hubble is snatched and placed in the Columbia's cargo bay its solar arrays will be rolled up and removed. The 10-year old solar wings will be replaced with brand-new ones during the first two spacewalks.

Originally installed in a 1993 mission to fix the telescope's mirror, the solar arrays have degraded to the point where they had been operating at 65 percent of the original power.

The new solar arrays will generate 5,270 watts or approximately 30 percent more power than their predecessor. This, despite the fact that the new arrays are one third smaller than the previous arrays. Furthermore, during the second spacewalk the astronauts will also replace a faulty pointing control device.

The third spacewalk, however, may be the riskiest of the mission. During the spacewalk astronauts Grunsfeld and Linnehan will replace the Hubble's Power Control Unit or PCU. Described as the heart of the electrical system on the Hubble, the PCU has been plagued by circuitry problems. The PCU, a power switching station with 36 attached heavy cables, was one of the few components of the Hubble not designed to be replaced.

Thus, in order for the PCU to be replaced the telescope must be completely powered down, the first time this will be done since its launch. The powering down is a precaution being taken to ensure that the astronauts are not electrocuted during the replacement. However, the work must be completed in less than eight hours, as the telescope must be powered up in order to ensure that none of the sensitive instrument or systems freeze up or overheat.

If the replacement fails, the Hubble would be nothing more that a piece of junk.

"We fully anticipate that everything will work fine? but it is a risk we've never faced before," said NASA space science chief Edward Weiler.

Should all go to plan, the fourth spacewalk will install the ACS. The final spacewalk will be an attempt to revive the Near Infrared Camera and Multi-Object Spectrometer, or NICMOS which ceased to function in 1999. The NICMOS was capable of seeing through interstellar gas and dust in order to watch the birth of planets, stars and galaxies, until its cooling system failed. During the spacewalk, the astronauts will attempt to install a new experimental cooler in order to provide cooling to NICMOS.

The timeframe for all these repairs and modifications: five to six days, maximum.

"This will be by far the most challenging, ambitious servicing mission to date? most of the tasks are very lengthy and complex. They will challenge the endurance and stamina of the astronauts," according to Preston Burch, manager of the Hubble project from NASA.

While mission commander Altman readily acknowledges this fact, "It's really an awesome responsibility when you think about it," he also announces "Hubble's up there ready for us and we're ready to go to work."

While the task is large, the payoff is equally grandiose, according to Grunsfeld "Hubble will be significantly better than it's ever been, and we'll have new capabilities that I think will boggle the imaginations of astronomers and people all over planet Earth.