This is probably what the demise of the Hubble Space Telescope was always going to look like: components failing one by one, with no way to replace them. In the last few months, the Hubble has repeatedly gone into safe mode as one of its remaining three gyros keeps giving faulty readings. But the Hubble and the people operating it are resilient and resourceful. The telescope is back to science operations now, though in single gyro mode.
NASA has released the first image the Hubble captured in this mode, and it’s clear that the Hubble is performing well.
This image is Hubble’s contribution to a three-telescope, multi-wavelength observing effort. The James Webb Space Telescope (JWST- infrared) and the Atacama Large Millimetre/submillimetre Array (ALMA-radio) are both involved. Hubble captured this image with its Wide Field Camera 3 (WFC3.)
“Hubble’s new image of a spectacular galaxy demonstrates the full success of our new, more stable pointing mode for the telescope.”
The image shows the lenticular galaxy NGC 1546, which is about 61 million light-years away in the constellation Dorado. The galaxy is oriented so that the glow from its core lights up dust lanes. The dust absorbs starlight and then emits it again at lower wavelengths, making the dust appear brown. The core is yellowish, which indicates a population of older stars. Bright blue regions peeking out from the dust lanes are where active star formation is taking place. Background galaxies are also visible, including an edge-on view of a reddish spiral galaxy on the left.
The Hubble started its mission with six gyros, which help the telescope point itself at chosen targets. There are now only three left, and one of them is repeatedly causing problems. NASA says the gyro is experiencing ‘saturation,’ meaning it also indicates that the Hubble is at its maximum slew rate, regardless of the actual slew rate.
But as this image shows, science operations are still continuing effectively, even though NASA says there are some minor limitations in the single gyro mode. In this mode, the telescope’s view of some regions of the sky is limited. The single gyro mode is part of the telescope’s design, just in case four or five of its six gyros fail.
It’s amazing that the space telescope can operate with a single gyro. It can capture the light from objects billions of light years away while travelling at about 27,000 km/hour (17,000 mp/h). All the while, it keeps its pinpoint gaze steady. NASA describes it as keeping a laser shining on a dime over 320 km (200) miles away. The telescope requires long exposure times; sometimes, it focuses on a single time for 24 hours.
This is Hubble’s second set of six gyros. They were all replaced during a 2009 servicing mission.
In this image, astronaut Mike Massimino works to remove and replace Hubble’s Rate Sensor Units, which contain the telescope’s gyroscopes, during Servicing Mission 4 in 2009. All of Hubble’s gyroscopes were replaced during the mission. Image Credit: NASA“Hubble’s new image of a spectacular galaxy demonstrates the full success of our new, more stable pointing mode for the telescope,” said Dr. Jennifer Wiseman, senior project scientist for Hubble at NASA’s Goddard Space Flight Center in Greenbelt, Maryland. “We’re poised now for many years of discovery ahead, and we’ll be looking at everything from our solar system to exoplanets to distant galaxies. Hubble plays a powerful role in NASA’s astronomical toolkit.”
Everything has a beginning and an end, including the Hubble. Over time, gyros and other equipment will continue to fail. Just like other aged spacecraft, like the Voyager Probes, engineers and mission staff will adapt and find new ways to keep the telescope going, probably with reduced results. But one day, the space telescope will cease functioning.
Considering all that Hubble has contributed, it will be a very sad day when the telescope shares its final image with us.
