boldly going

As I write this, astronauts aboard the shuttle Atlantis have finished repairs to the Hubble Space Observatory. By all reports this risky and ambitious mission has been a success, giving the Hubble its fifth reincarnation. Assuming that the shakedown cruise goes well in the coming months, NASA expects that the Hubble will continue to be our one true starship for another five or perhaps even ten years.

Starship? Okay, so maybe I have interstellar travel on my mind these days; just last week I saw the new Star Trek (startrekmovie.com). What did I think? Well, Sheila doesn’t pay me to review movies and, by the time you read this, all of you who care will have already seen it and thus have your own opinions. But if you ask me, although it is certainly is a rousing adventure and it successfully re-imagines the characters so dear to us (startrek.com/startrek/view/series/TOS/casts/index.html) , it doesn’t appear to have an original SF thought in its pretty little head.

Oh right, blowing up planets is not cool.

But this is just an origin story and there are bound to be multiple sequels, so there is time for J.J. Abrams (en.wikipedia.org/wiki/J._J._Abrams) and his crew to figure out what the hell the Enterprise is boldly going to the stars for.

We do know, however, what the Hubble is doing. Astronomy and all its associated fields: planetary science; stellar, galactic, and extra galactic astronomy; astrophysics; and cosmology. It is without a doubt one of NASA’s greatest hits, perhaps the greatest. Although it is much beloved and has been nicknamed “the People’s Telescope” the Hubble has had a checkered history.

The first serious proposal for a space telescope was floated in 1946 by Lyman Spitzer, Jr. (spitzer.caltech.edu/about/spitzer.shtml) , who continued to push for his idea right up until congressional authorization in 1977. He pointed out the two principal advantages of a space-based observatory: it is not hindered by atmospheric distortion and it can make observations in wavelengths like ultraviolet, gamma, and X-rays that are blocked or absorbed by our atmosphere. The new space telescope was named after the cosmologist Edwin Hubble (edwinhubble.com), who was the first to confirm that the universe was expanding.

Hubble’s troubles started when Perkin-Elmer (perkinelmer.com) was awarded the contract for the primary light collecting mirrors. For various reasons, the company had problems delivering in a timely manner, so that the projected 1983 launch date was postponed to 1985. Then, just after the Hubble was completed, the Challenger exploded and the space shuttle fleet was grounded. For five years NASA kept the Hubble on layaway, powered up in a clean room at a cost of six million dollars a day. Finally, in April of 1990, the Hubble was boosted to low Earth orbit aboard the shuttle Discovery (en.wikipedia.org/wiki/STS-31) . A few weeks later, it started beaming the first pictures back to Earth.

And they were out of focus. To the world’s universal chagrin, we discovered that our far-seeing space telescope needed glasses. A blue ribbon commission (http://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/19910003124_1991003124.pdf) was convened to investigate the problem; it put the primary blame on Perkin-Elmer, but also cited NASA for failing to note “that the mirror was made in the wrong shape, being too much flattened away from the mirror’s center. . . . The error is ten times larger than the specified tolerance.” It was at this time that NASA and its billion dollar boondoggle became fodder for snarky comedians, who likened the Hubble to such technological fiascos as the Titanic, the Hindenburg, and the Edsel. It was not a promising start for the People’s Telescope.

However, the Hubble had been designed from the start to be serviced as necessary by the shuttle fleet, and so in 1993 NASA dispatched the Endeavour (en.wikipedia.org/wiki/STS-61) to correct the problem. In one of the most complex missions in shuttle history—until the most recent one—astronauts installed both a corrective optics package and the Wide Field and Planetary Camera 2 (hubblesite.org/the_telescope/nuts_.and._bolts/instruments/wfpc2/), which has taken most of the pictures for which the Hubble is justifiably famous. They also replaced solar arrays, gyroscopes, various electronics systems, and upgraded the onboard computer. The Hubble was saved—for the time being.

Altogether there have been five Servicing Missions, although the most recent almost didn’t happen. In the wake of the Columbia disaster (space.com/columbiatragedy) it was deemed too risky to send a shuttle to Hubble. All of the post-Columbia missions had to be able to reach the International Space Station (nasa.gov/mission_pages/station/main/index.html) in case of emergency, where it was possible to inspect a shuttle for damage and, if necessary, have the crew take refuge while they waited for rescue. This was not an option with a Hubble visit, so in 2003 NASA announced that it was scrapping the last service mission and preparing plans for a robot to push the space telescope out of orbit so that it would burn up safely in the atmosphere.

This touched off a firestorm of protest from friends of the Hubble, both in the scientific community and in the general public. Websites went up, Congress held hearings, and schoolchildren sent their lunch money to save “the People’s Telescope.”

And so the Hubble was saved—for the time being.

Because this recently completed mission (en.wikipedia.org/wiki/STS-125) is positively, absolutely the last time that a shuttle will be available for a servicing mission. The fleet will be retired in 2010; the first round of layoff notices (space.com/news/090501-nasa-shuttle-layoffs.html) have already gone out to shuttle contractors. Originally, the Hubble was to be retrieved at the end of its mission and brought back to Earth in a shuttle cargo bay. But there will be no place of honor in the Smithsonian (nasm.si.edu/) for this space pioneer. Current plans call for a robotic craft to lock onto it sometime after 2020 and “deorbit” the Hubble.

seeing

Although it is commonly referred to as a space telescope, the Hubble is more properly a space observatory. Of the five instrument systems on board, the output of the Wide Field and Planetary Camera 2 (WFPC2) and the Advanced Camera for Surveys (ACS) are the best known; these take the stunning pictures (heritage. stsci.edu/gallery/galindex.html) of our universe that grace posters and screen savers around the world. On the mission just concluded the WFPC2 was replaced by the Wide Field Camera 3. The ACS, the Hubble’s “telephoto lens,” had been malfunctioning, operating with only one of its three channels available to scientists; it was successfully repaired. These systems detect visible light from the most distant, highly redshifted galaxies. They have found massive planets and have been instrumental in mapping the distribution of dark matter (science.howstuffworks.com/dark-matter.htm).

The Near Infrared Camera and Multi-Object Spectrometer (NICMOS) is Hubble’s heat sensor. Interstellar gas and dust can block visible light, so the NICMOS sees in the infrared, which is invisible to the human eye. It therefore can see even further than the visible light instruments and is particularly suited to detecting newly forming stars and clusters.

The Space Telescope Imaging Spectrograph (STIS) is a powerful general-purpose spectrograph that allows scientists to examine the chemical fingerprints of distant objects. The STIS has analyzed the chemistry in the atmosphere of extrasolar planets and has detected super-massive black holes (csep10.phys.utk.edu/astr162/lect/active/smblack.html) rotating at the centers of several galaxies. The STIS failed in 2004, but was resuscitated in the most recent mission.

The Fine Guidance Sensors (FGS) are devices that lock onto the Cepheid variable stars (imagine.gsfc.nasa.gov/docs/science/mysteries_l1/cepheid.html) to aim the Hubble in the right direction. These so-called “guide stars” have been used by modern astronomers to measure distance in space; however, until Hubble and its FGS, those measurements were known to be inaccurate. The data returned by these sensors has helped us pinpoint distances in the universe, refine the Hubble Constant (cfa.harvard.edu/~huchra/hubble), and estimate the size and age of the universe.

Black holes, dark matter, extrasolar planets, galaxy formation, the age and size of the universe—Hubble has confirmed some theories about the nature of the universe, called others into question and, in the process, spectacularly fulfilled its mission. In the scientific community, that would easily account for its popularity. But why has it become “the People’s Telescope?” I think it is because, unlike much of our technology, it has a story. The Hubble has ever ridden a rollercoaster of expectations. Its history is filled with crushing disappointments and dazzling recoveries.

But perhaps there is something more.

exit

Back to Star Trek for a moment: I am old enough to remember when the original series made its debut on television. As you might expect, this fifteen-year-old was pretty much hooked, as much by the future Star Trek seemed to promise as by the plots and the characters. Like me, many science fiction fans at the time were convinced that, while our future in space would not necessarily involve velour uniforms and dilithium crystals, humans would leap someday to the stars. Maybe even Jim Kelly! In 1966, it didn’t seem all that farfetched. According to the holy trinity of science fiction—Heinlein, Clarke, and Asimov—stardrives were very doable.

My longtime readers might remember a column entitled FTL (asimovs.com/_issue_0406/onthenet.shtml) , wherein I reviewed all the reasons why faster than light travel is more fantasy than science fiction. I doubt very much that humanity is going to the stars, at least not in a starship. As the history of the Hubble and the shuttle program show, even getting to orbit is fraught with peril. Missions to space are far from routine.

But in our starship of the mind we have traveled some twelve billion light years from Earth, exactly at the speed of light. With the aid of images taken by the Hubble we have witnessed planets being born and the death of stars. We have ventured to distant galaxies and soon, with the improvements just installed, may be able to see back in time and space to the universe’s adolescence, some five hundred million years after the Big Bang (umich.edu/~gs265/bigbang.htm) . It seems to me that’s one reason why the Hubble has so endeared itself to the world.

Pictures may not be exactly what we wanted, but they are enough, thanks to “the People’s Telescope"