Johns Hopkins University

Spring 2008
Vol. 5, No.2

RESEARCH

>A Eulogy to FUSE

Pooling Expertise to Combat Pollution

Student Research: From the Field

High-Tech Access for a Centuries-Old Poem

For Female Would-Be Presidents, Press is Hard to Get

Fractured Origins

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A Eulogy to FUSE

As a child, Bill Blair used to wonder what happened when satellites broke while in orbit—did NASA go up there to fix them? After eight years at Johns Hopkins working as chief of observatory operations for the FUSE space telescope, he now knows the answer. Sometimes you do what you can from the ground. And sometimes, when old satellites die, you just have to let them go.

Launched in 1999, the Far Ultraviolet Spectroscopic Explorer (FUSE) was a workhorse for the astronomy community. Its instruments could detect the ultraviolet light given off by heavenly bodies—light that is invisible to the human eye, but that contains information about phenomena including the auroras of Jupiter and the dust that permeates the space between galaxies. "It looked at a little bit of everything," says Blair, a research professor in the Department of Physics and Astronomy. Astronomers across the globe tapped into the data provided by the space telescope, producing hundreds of research papers.

When FUSE originally launched into orbit 475 miles above the Earth, its mission was only supposed to last for three years. When it was retired last October, it had celebrated seven birthdays. The secret to its longevity, according to Blair: many sleepless nights for the mission control crew, who operated out of a control room in the basement of the Bloomberg Center for Physics and Astronomy. (FUSE is the largest astrophysics mission that NASA has ever handed off to a university to develop and operate.)

The challenges started in December 2001, when two of the four spinning wheels that control the direction of the scope broke. With no way to rocket up to FUSE to fix the broken parts, NASA was ready to pull the plug. But after eight months, the Hopkins team figured out how to program other on-board devices—called magnetic torquers—to compensate. Normally used to stabilize the scope, the torquers could produce about 10 percent as much force as a single wheel by interacting with the Earth's messy magnetic field. "It was like having a couple of strong muscles and one very weak muscle," says Blair. But it worked.

When a third wheel malfunctioned near the end of 2004, the team spent nearly 10 months readjusting the magnetic torquers. The jerry-rigged scope was limited to observing a much smaller region of space--barely able to fight the pull of gravity to turn itself--but its eyes could still see perfectly and gather great data about the objects in that patch of the cosmos.

Then the fourth and final wheel bit the dust last July. Without any strong muscles to point the scope, the team had to call it quits. In October, the scientists sent a small suicide pulse to their instrument, turning it into a dead hunk of metal and glass. It continues to orbit, slowly decaying until it will burn up in the atmosphere decades from now. But even as it experiences a cosmic cremation, FUSE's legacy will live on. It may take the astronomy community decades to sort through the massive amount of data that this tough old telescope left behind.