What's Next for Hubble?
When the crew of the Space Shuttle Atlantis released the Hubble Space Telescope to return to orbit, concluding the final astronaut mission to upgrade and repair Hubble, astronomy fans around the world rejoiced. Hubble, renewed and equipped with new cameras, would now return to its work of revealing the universe.
But after the furor and high-profile feats of a servicing mission, Hubble sinks into silence. This time, a three-month hiatus will take place between the mission and any new images.
The quiet belies the intense activity going on behind the scenes. Engineers and scientists are conducting a slow, painstaking process of Servicing Mission Observatory Verification (SMOV) bringing the telescope to full functionality, making the adjustments and gathering the information that will allow them to provide the best, clearest, cleanest images. Once that's accomplished, Hubble will begin taking its Early Release Observations (EROs), images intended to demonstrate the telescope's new technology.
At the Space Telescope Science Institute in Baltimore, Md., and Goddard Space Flight Center in Greenbelt, Md., teams work together to make sure the telescope is pointing correctly and that its instruments are working with their intended precision.
Hubble's pointing is adjusted with the help of six gyroscopes, all of which were replaced during Servicing Mission 4. To ensure that the telescope is pointing accurately, engineers change the direction of the telescope in a measured way, and then examine the data generated from the gyroscopes. The data is then used to calibrate the gyroscopes to ensure precise pointing.
Next, engineers and scientists look at Hubble's instruments. The instruments are in the natural process of "outgassing" the extra, unwanted molecules within them from their time on Earth are floating away due to the lack of atmospheric pressure.
Outgassing is important for a couple of reasons: the molecules can interfere with the instrument when high voltages are present, possibly damaging it; and they can absorb wavelengths of light, preventing the instrument from collecting all the information it could. To avoid these dangers, engineers wait until the outgassing is complete before bringing the instruments to full power.
The new instruments weightless for the first time, and now in the vacuum of space will be out of alignment. But that's expected, so the instruments are built with mechanisms that allow engineers to adjust them from the ground, often by moving small mirrors within the instrument itself. Each instrument needs a few weeks to go through the alignment process.
Finally, engineers take the instruments through a calibration process. Calibration is the process of identifying and dealing with data that belongs to the instrument, versus data that belongs to the sky.
Engineers observe a familiar astronomical object and compare the data they receive with the data they know should be there. They can then adjust the instruments to remove the data that comes from the instrument itself, or, more frequently, arrange to have it removed on the ground. Finding and identifying this erroneous data is a major part of the SMOV process.
Once all these tasks, have reached a particular point in the plan, Hubble starts taking its Early Release Observations (EROs), the first high-quality images from the telescope. The targets have been chosen in advance by a team that selects them for their ability to showcase Hubble's new capabilities.
The targets are kept a mystery until their release, but the goal is to provide the most impressive views of a good mix of astronomical objects some within the galaxy, some far beyond.
To those who know what to look for, the new images will be the first true display of the power of Hubble's new technology, dazzling amateur and professional astronomers with a wealth of new information. Scientists will immediately have access to the images for use in their research. These compelling images are expected to be released in September.
As the ERO images are completed, Hubble will go back to the day-to-day task of observing the universe. Equipped with new eyes and fresh technology, it will work ceaselessly, minute by minute, to answer the pressing questions of modern astronomy. Though the servicing missions may be over, Hubble's revelations will continue far into the future.
Space Telescope Science Institute