Friday, July 10, 2009

What Happens After Hubble?

This is the International Year of Astronomy -- 2009 marks the 400th anniversary of Galileo's use of a telescope to study the skies, and Kepler's publication of Astronomia Nova. It's also the year that NASA gave the Hubble telescope its fifth update, extending its life to about 2014, when the James Webb Space Telescope (JWST), a large, infrared-optimized instrument, will replace Hubble and start sending back images of the Universe.

Tom Griffin, a University of Michigan engineering alum, has been the Hubble Space Telescope Observatory Manager since 1997.  Working at the Goddard Space Flight Center, Griffin was in charge of the Hubble spacecraft flight hardware installed during the space shuttle's recent servicing mission in May.  He said that the most remarkable legacy of Hubble would be "its phenomenal discoveries that have rewritten astronomy textbooks. Hubble's lifespan has been extraordinary, too -- and it'll continue to be a productive scientific instrument for discovery through about 2014. This has all been achievable because Hubble's design facilitated in-orbit servicing -- the Space Shuttle and its crew could carry out their updating missions with a high degree of assurance that they'd be successful, as they were with the STS-125 mission in May, which left Hubble able to operate with peak efficiency and productivity. The crew installed two new state-of-the-art science instruments and repaired two others -- those, plus the spacecraft components they installed, such as the gyroscopes, batteries and fine guidance sensor, should allow continued operations."

JWST, the next generation space telescope, will be bigger than Hubble, but the real key to its "eyesight" will be a process that cools structures such as its multiple segmented hexagonal mirrors to 225 degrees below zero Centigrade and gives it the ability to detect light that's red-shifted into infrared from deep space. It's technology that'll enable JWST to eclipse Hubble' capabilities -- astronomers will be able to look at galaxies that formed in the very beginnings of the Universe and, in the process, connect the Big Bang to our own Milky Way Galaxy.

Thomas Zurbuchen, an engineering professor in the University of Michigan departments of Aerospace and Atmospheric, Oceanic and Space Sciences, said that JWST "is going to become the new Hubble -- a telescope that will change the way we look at the universe and a set very high standard for the entire field of astronomy. As compared to Hubble, JWST will be able to look much deeper into the infrared and thus be able to look much further into the past towards the very beginnings of Universe. With this new and improved capacity, we'll also be able to make new observations that'll provide measurements of the chemical properties of planetary systems and thus shed new light on the processes that are responsible for life."

Katherine Freese, another University of Michigan professor, is studying "dark stars," which she believes might have been the first stars to form in the early universe and which would have burned out by now or might have evolved into something unlike anything we currently know about. JWST will be able to detect these mysterious interstellar creatures.

"Guessing from the Hubble experience, we should expect that JWST will discover entirely new aspects of many fields in astronomy," Zurbuchen said. "The most affected will be questions that relate to the earliest stage of the Universe, galaxies, the birth of new stars and the search and analysis of planetary systems."

Existing instruments, such as Hubble, are unable to detect non-solar planetary systems (planets orbiting stars other than the Sun); however, detection of non-solar planetary systems would play a major part in determining the origin of our solar system and in the search for extraterrestrial intelligence. JWST's infrared is ideal for this kind of exploration -- when you look at the ratio of power of radiation received from stars and planets, infrared offers an advantage of about 105 over visible light.

NASA hopes to keep JWST operational for more than 10 years, but that'll depend not only on the amount of fuel needed to maintain the telescope's orbit but on the ability of the craft's instrumentation to keep functioning. JWST's distance from Earth -- about 1 million miles -- will make it impossible to service in the same way that NASA now services Hubble, which orbits about 375 miles above the Earth's surface.

Science will never forget Hubble but, come 2014, JWST will command everyone's attention. Who could resist a look at the infant Universe and objects that are now only matters of speculation?

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