Hubble approaches 25 years
As it nears its silver anniversary, the telescope that changed the way we see the universe remains dominant in its field
GREENBELT, Md. — The Hubble space telescope turns 25 on Friday, but no one should call it old. It’s mature. It’s the great silverback of astronomy, grizzled from wear and tear and yet still powerful and utterly dominant in its field.
The Hubble changed our understanding of the age of the universe, the evolution of galaxies and the expansion of space itself. Along the way it has had the equivalent of knee- and hipreplacement surgery: Five times, astronauts on the space shuttle paid a visit to swap out old batteries and install new instruments, including, in 2009, the best camera the telescope has ever had.
“It’s fantastic. It’s better than ever. That’s not just hype, it’s the truth,” said Jennifer Wiseman, the senior project scientist for the Hubble at NASA’s Goddard Space Flight Center.
“This is 1970s technology, and it is still, after 25 years, the most powerful scientific instrument in the world,” said astrophysicist Patrick McCarthy of the Giant Magellan Telescope under construction in Chile.
However, the great telescope is essentially stranded in space.
The Hubble was designed to be serviced by the space shuttle. But the space shuttle fleet was retired in 2011, and the Hubble hasn’t had a repair job since that 2009 mission. At some point, the Hubble will begin to deteriorate — for example, losing its navigational ability as its gyroscopic sensors fail one by one.
“It’s kind of like predicting when’s the next time your car’s going to break down,” said Jim Jeletic, deputy project manager for the Hubble at NASA Goddard. Electronics eventually go haywire in a space environment that is flush with radiation. As it orbits the Earth 15 times a day, the 13-metre-tall Hubble goes in and out of sunlight, expanding and contracting, and that puts stress on various systems.
The Hubble was conceived in the 1940s, designed in the 1970s and 1980s, and still has vintage hardware on board, including a 1980s-era computer that freezes up occasionally and has to be rebooted remotely.
And then there’s gravity. The Hubble is orbiting the Earth about 547 kilometres above the surface, significantly higher than the International Space Station. There’s just a trace of atmosphere that high, but it’s enough to drag the Hubble a tiny bit and cause it to descend a little over a kilometre per year. NASA said this week that, based on current orbital projections, the Hubble is expected to re-enter the atmosphere “around 2037.”
One option would be to send a robotic craft to dock with the Hubble and guide it to a fiery, but controlled, re-entry into the Pacific Ocean. Another option would be to boost the telescope to a higher, “parking” orbit where it would stay for centuries as a piece of space junk.
“When the time comes, NASA will make a decision on the disposal plan. Until then, NASA will continue operating Hubble as long as the hardware lasts, enabling it to remain scientifically productive,” NASA spokesman Dwayne Brown said.