Lost in space

THESE SHOULD BE among the best days of Adam Riess's career. Riess, an astronomer at the Space Telescope Science Institute in Baltimore, has helped spearhead ground-breaking research in recent years showing that a mysterious force called "dark energy" is rapidly pushing the universe apart. He has won a fistful of academic prizes, authored influential papers, and even gained recognition from the popular press: The December issue of Esquire, to Riess's bemusement, named him one of the country's "best and brightest."

But Riess is also among a group of scientists who now face an abrupt halt to their studies. Like many of his colleagues, he relies heavily on data from NASA's Hubble Space Telescope. When NASA announced in January that it would no longer use the space shuttle to service the Hubble, which means that the telescope will stop working within a couple of years, Riess was stunned. "I was very disappointed," Riess says. "Crushed."

His reaction is not unique. "It's a real disappointment," says J. Michael Shull, chair of the Astrophysical and Planetary Sciences department at the University of Colorado. Since 1998, Shull has helped a Colorado team build a new instrument for Hubble -- the Cosmic Origins Spectrograph -- intended to let scientists study how galaxies form and evolve. The spectrograph is now sitting in storage, and about 20 jobs at Colorado have been erased by NASA's decision. "That rug was pulled out from under us overnight," Shull says.

Astronomers and historians of science alike say they cannot remember any other time in modern scientific history when the world's most powerful telescope was simply abandoned, without a better one ready to replace it. "Usually other instruments are there and taking over," says Owen Gingerich, emeritus historian of science at Harvard University who specializes in astronomy. "You don't have this interim gap where you throw away an instrument that is producing heavily in anticipation of something else."

Moreover, though the politics of NASA's decision have been widely debated -- the agency says its rationale is safety, but skeptics believe the Hubble is being sacrificed to pay for President Bush's goal of sending astronauts to Mars -- fewer people recognize that scientists are enjoying one of the most productive moments in Hubble's history.

Granted, NASA plans to launch another large instrument, the James Webb Space Telescope, in 2011, which will pick up some scientific slack -- but its original launch date has already been delayed four years. Plans for other telescopes are a decade or more away, and astronomers worry that the resulting gap will not only slow astronomy, or make bright graduate students gravitate to other fields, but may diminish general interest in the cosmos.

"The public has this opportunity to watch the next chapter of scientific discovery being made in front of them," says Saul Perlmutter, a prominent astrophysicist at Lawrence Berkeley National Laboratory in Berkeley, Calif., "and they're being asked to sit it out for potentially half a generation."

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For those who only remember Hubble's ignominious launch in 1990, when it entered orbit with a defective mirror, the current controversy may seem surprising. Since `93, though, when space-walking astronauts repaired the telescope, Hubble has produced a spectacular series of images that have often landed on front pages around the world: dust clouds, swirling galaxies, supernovas, the comet Shoemaker-Levy 9 slamming into Jupiter, and more.

But pictures are just part of Hubble's value. Astronomers have long analyzed starlight to determine the composition of the cosmos. Today, they often examine light beyond the visible spectrum, at the infrared, ultraviolet, or x-ray frequencies. Orbiting 350 miles above the atmosphere (which blocks many of those rays), unaffected by man-made light or bad weather, Hubble can study starlight more precisely, with greater range, than any telescope ever made. NASA's three previous trips to Hubble have also updated its technology. "Although the telescope gets old, the instruments are always new," says Riess.

With this ever-improved technology on board, Hubble has produced important evidence involving the most elemental questions about the cosmos, from the size and age of the universe to the formation of galaxies, stars, and planets. It has also provided new insights into the nature of more exotic cosmic phenomena, like black holes, quasars, and gamma rays.

Two major research areas are likely to suffer most from Hubble's demise. One is the study of dark energy, which is used to map the universe. The other involves the formation of stars and galaxies relatively soon after the Big Bang occurred, about 14 billion years ago. A glance at each brings the Hubble hubbub into sharper scientific focus.

The existence of dark energy, first postulated in 1998, stems from an older discovery. About 75 years ago, Edwin Hubble himself -- America's most famous 20th-century astronomer -- realized the universe was expanding. Synthesizing previous research, Hubble recognized that because certain stars (known as Cepheid variables) have a regular size and luminosity -- astronomers call them "standard candles" -- their relative brightness indicates their distance from Earth (much as, say, identical streetlights will appear dimmer in the distance).

Additionally, light moving away from us leaves a telltale infrared mark, so the velocities of stars (from our vantage point) can also be measured. Since light moves at a constant speed -- 186,000 miles, or some 30 round trips between Boston and San Francisco, per second -- it became possible for Edwin Hubble to sketch out the size and age of the universe.

Similarly, contemporary astronomers use an exploding star, called a Type 1a Supernova, as a "standard candle." These supernovas can be seen from a greater distance than Cepheid variables, giving us a bigger celestial map. "They're like stepping stones," says Riess, "and we step our way back to ever dimmer and more distant supernovae."

These stars have yielded crucial clues about the universe's expansion. Many scientists once assumed that gravity was slowing the growth of the universe. Six years ago, however, two teams of scientists -- one including Riess, the other headed by Perlmutter -- used supernova measurements to demonstrate that the universe's expansion was accelerating. "Dark energy," as cosmologist Michael Turner dubbed it, is the pressure apparently pushing galaxies apart from each other, and responsible for the expansion of space itself.

Scientists are still trying to determine if the expansion of the universe abruptly sped up about 7 billion years ago, or whether it has accelerated at a more consistent rate. Either way, the data is limited -- and largely dependent on Hubble. Supernovas are rare, and bright as these cosmic explosions may be, only Hubble can perceive many of them. Consider: The total number of Type 1a supernovas useful for gauging dark energy is currently in the double digits, but in the last year, Riess's team has charted six of the seven most distant yet seen.

"In just one year of using Hubble on this problem, which we haven't been able to do before, we've almost tripled our precision in our knowledge of the fundamental properties of dark energy," says Riess.

And since only select wavelengths of infrared light penetrate the earth's atmosphere, only Hubble can measure the speed of many stars. Tantalizingly, a more powerful camera for supernova-hunting, the Wide Field Camera 3, is also currently waiting to be added to Hubble.

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Hubble's awesome range also makes it invaluable for a more conventional line of inquiry, the study of early star and galaxy formation. Light produced by each element yields a different pattern when viewed though a spectrograph (which separates light into its constituent parts). Scientists can thus deduce what elements are in a burning candle -- or a distant star, if a spectrograph is good enough.

That's where Shull's instrument, the Cosmic Origins Spectrograph, comes in. The Space Telescope Science Institute, which handles Hubble's scientific operations, announced this month that Hubble has now viewed stars more than 13 billion light years away -- stars so distant that the light now reaching us was released within a billion years of the universe's creation. The Cosmic Origins Spectrograph, 20 times more sensitive than Hubble's current spectrograph, would analyze this ancient light -- and be able to reconstruct how galaxies like our own were formed.

Much of that galactic evolution, literally and figuratively, revolves around stars. Current cosmology holds that after the Big Bang, the universe expanded and cooled, with hydrogen clouds forming the first stars. Those stars, by heating up and burning out, produced and spewed out other elements -- including the ones necessary to support life. "Hydrogen and helium were formed in the Big Bang," says Richard Ellis, a professor of astronomy at Caltech, in Pasadena, Calif., "but all the metals, like carbon, magnesium, and silicon, were formed in the centers of stars."

Eventually star debris, clumping with other cosmic detritus thanks to gravity, formed solar systems around newer stars. Many scientists think the first billion years after the Big Bang was a time of rapid cosmic evolution -- precisely the period that Hubble has now reached. In this sense, Hubble is not just a telescope but a time machine. "That's exploration," says Shull. "To me, it's more fun than going to Mars."

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Not everyone, of course, will agree with that sentiment. While thousands have signed online petitions to save Hubble, NASA spokesman Donald Savage says the agency has not received many direct calls and letters about the telescope.

Ultimately, any choice between Hubble and a manned Mars mission is a choice between two distinct modes of astronomical exploration. Mars presents a specific, long-term undertaking -- and an all-or-nothing gamble. Hubble would provide a wider-ranging, more immediate, and steadier flow of discoveries.

Perlmutter, for one, believes that such broad, steady progress will best raise the level of science and technology available over time, to the benefit of everyone. He envisions science classes studying new telescope discoveries on the Web, thus inspiring the scientists, engineers, or inventors of the future. He says, "People get so excited by these kinds of questions that it really makes a huge difference for our whole society."

Peter Dizikes is a journalist living in Arlington, Mass.