May 8, 2009

Last Hubble Mission To Be Most Challenging

The famous Hubble telescope is about to get a visit from its terrestrial creators, as astronauts plan on Monday to blast off from the Kennedy Space Center in Florida, taking with them new scientific equipment and replacement parts for the 19-year old orbiting observatory.

After some seven months of delays, the mission will be NASA's most comprehensive and daring tweaking of the telescope yet.  Hitherto, astronauts have never attempted to repair the Hubble's instrumentation while in orbit and experts say the device was not really designed to be serviced in space.  In the past, missions have been made to swap out interchangeable parts, but intricate repairs of delicate parts and installation of significant new equipment has never before been attempted.

Over the course of five days, two repair teams will perform five spacewalks to work on the telescope.  Two of the five members have made previous visits to the Hubble and were chosen for the extremely challenging task largely on account of their familiarity with device.

"The Hubble needs a hug," said John Grunsfeld, the lead repairman for the mission who will be making his third visit to the telescope.

In addition to the unprecedented complexity of the repairs that will be attempted, the mission will also be one of the most dangerous that NASA has ever deliberately carried out.  Because of the Hubble's distant orbit outside the earth's atmosphere "“ some 350 miles up "“ the space shuttle Atlantis that will be carrying the crew will be exposed to a large amount of space debris that could potentially damage the craft.

Though NASA has already stated that it will have another spacecraft on standby and ready to launch a rescue mission if needed, they admit that it could take at least three to seven days to launch a second shuttle crew, offering no guarantee that they could reach the imperiled astronauts in time.

Nevertheless, all seven astronauts have agreed that the Hubble is worth the risk.

"I'm only going to do that if I think it's something really important, and I think Hubble is really important," said John Grunsfeld, an astronaut and astrophysicist who will also be onboard.  The telescope is "worth bringing up to date and extending its vision even farther."

Scott Altman, the mission's second commander added, "it's showing us the way" through the unknown depths of the universe.  "The next step is for us to try and go there."

Since its launch in 1990, the Hubble has circled the Earth more 100,000 times and logged almost three billion miles.  The immense hype surrounding its departure was, however, initially dampened as scientists quickly realized that the telescope's primary mirror had been improperly ground and was consequently sending back very blurry images.

The first repair launch in 1993 solved the problem by simply changing out lenses, and three additional trips "“ in 1997, 1999 and 2002 "“ made various improvements like installing newer hi-tech cameras.


Next week's final mission will also make perhaps the most significant upgrade that the telescope has ever seen.  The crew will be installing a $70 million dollar instrument designed by astrophysicists at the University of Colorado at Boulder and the University of California, Berkeley that will be used to explore the evolution of distant galaxies, solar systems and stars.

Built largely by UC Colorado's industrial partner, Ball Aerospace & Technology Corp., the Cosmic Origin Spectrograph (or COS) is capable of gathering and deciphering information contained in the ultraviolet light emitted by distant heavenly bodies.  Scientists say this data will allow them to look back in time billions of years to probe the early history of the universe.

The COS uses distant quasars as a "flashlight" to follow light as it passes through webs of long, narrow galactic filaments and intergalactic gas, intermittently separated by vast expanses of empty space.  Current theories state that a single cosmic web filament may stretch through hundreds of millions of light years.

"The main goal of COS is to look as far and as faint as possible to study the cosmic web of primordial gas to understand how galaxies formed," said Barry Welsh, a UC Berkeley astronomer who will be helping to analyze the new data received once the COS is in orbit and operational.

Functioning much like a prism, the COS is able to deconstruct light into its individual components, revealing information about the temperature, density, velocity, distance and chemical composition of distant galaxies and stars.

According to a statement issued by researchers associated with the project, the COS is roughly ten times more powerful than any previous instrumentation ever carried by the Hubble.

In the past 19 years, the Hubble has offered scientists important information on the age of the universe (13.7 billion years) and has captured some of the most breathtaking images of cosmic phenomena "“ like the celebrated picture of the Eagle Nebula, commonly referred to as the "Pillars of Creation."

Within a very tiny field of view, some ground-based telescope are able to see better than the Hubble, explained NASA's science chief, Ed Weiler.  "But you don't see Eagle Nebulas on the cover of Time magazine taken from the ground.  You see them from the Hubble.  Hubble still has a unique niche."

For the past several years, there had been some debate as to whether a robot could be used to make most of the needed repairs, but the proposed project was eventually scrapped by former NASA chief administrator Michael Griffin, opting instead to use astronauts.

Grunsfeld noted that while a robot could have likely handled some of the repairs, the new COS technology could have never been installed with anything but human astronauts "“ and even for them it will prove an extremely challenging task.

"It's right at the edge of what I think people can do," said Grunsfeld of the planned repairs and upgrades.

Additionally, the astronauts will be adding a new fine guidance sensor to the Hubble's pointing system, attaching a new steel skin to its damaged exterior and hooking up an improved capture ring to allow a robot-guided craft to attach to the telescope and guide it to a watery grave somewhere in the Pacific when the project expires in the 2020's.

"The increase in Hubble's capability and the life extension is going to be so phenomenal that  I'm just going to be thrilled to see it as it recedes onto the horizon as just another bright star," said Grunsfeld.

He says he's already planning an enormous party for when the Hubble falls from its heavenly orbit in another ten years or so after some 30 years of service to mankind.


Image 1: The Hubble Space Telescope as seen from Space Shuttle Columbia during Servicing Mission 3B (STS-109). Courtesy NASA

Image 2: The far ultraviolet detector, built by Space Sciences Laboratory physicists, is part of the Cosmic Origins Spectrograph to be installed on the aging Hubble Space Telescope. (Space Sciences Laboratory photo)


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