The Hubble Space Telescope, one of the most iconic instruments in the history of astronomy, faces new challenges as it enters its fourth decade of service.
Recently, NASA reported issues with one of Hubble's three remaining gyroscopes, which are essential for aiming and stabilizing the telescope.
Despite these setbacks, NASA remains optimistic about Hubble's future, emphasizing that the telescope can continue to perform groundbreaking science well into the 2030s.
NASA's Plan for Hubble's Future
Trouble with one of Hubble's gyroscopes prompted mission managers to switch to a backup control mode. This change will limit some observations but will keep the telescope operational. "We still believe there’s very high reliability and likelihood that we can operate Hubble very successfully, doing groundbreaking science, through the rest of the 20s and into the 2030s," stated Patrick Crouse, the Hubble project manager.
The gyroscope issue became apparent on May 24, when gyro No. 3 was taken offline due to erratic behavior. This left Hubble operating with only two functioning gyroscopes. NASA developed a software solution years ago to operate Hubble with just one gyro, keeping another in reserve. While this mode reduces efficiency, it extends the telescope's operational life. "Our team first developed a plan for one-gyro operations over 20 years ago, and it is the best mode to go forward to prolong Hubble’s life," Crouse said. This plan allows the telescope to continue capturing high-quality data, albeit with some limitations in its field of view and maneuverability.
Hubble's Gyro Challenges
Launched aboard the shuttle Discovery on April 24, 1990, Hubble initially suffered from a flawed mirror that prevented it from focusing starlight correctly. A corrective mission in 1993, involving spacewalking astronauts, installed new instruments and mirrors that fixed the issue, transforming Hubble from a national embarrassment into a symbol of scientific achievement. Over the years, Hubble has undergone multiple servicing missions, the last of which occurred in 2009, to replace aging components, including its gyroscopes.
The gyroscopes are critical for Hubble's operation, as they allow the telescope to lock onto targets with high precision. Originally equipped with six gyros, Hubble now relies on the three remaining units installed during the last servicing mission. With the recent failure of gyro No. 3, NASA is implementing a single-gyro operation mode to extend the telescope's life. "There are some limitations. It will take us more time to (move) from one target attitude to the next and to be able to lock on to that science target," explained Crouse, noting a reduction in scheduling efficiency by about 12 percent.
Reboost Mission Considerations
Despite the gyro failure, NASA has ruled out, for now, a proposed commercial mission to boost Hubble to a higher altitude using a SpaceX Crew Dragon spacecraft. This mission, suggested by SpaceX and entrepreneur Jared Isaacman, aimed to extend Hubble's operational life by reducing atmospheric drag.
However, NASA's current assessment highlighted potential risks and technological challenges that outweigh the immediate benefits. "We greatly appreciate the in-depth analysis conducted by NASA and our partners, but we believe we need to do some additional work to determine whether the long-term science return will outweigh the short-term science risk," said Mark Clampin, director of astrophysics at NASA Headquarters.
Hubble's Continuing Contributions
Hubble's ability to conduct world-class science is complemented by the capabilities of the James Webb Space Telescope (JWST), which observes in the infrared spectrum. Together, these telescopes provide a comprehensive view of the universe, with Hubble focusing on visible light observations. The synergy between Hubble and JWST is expected to yield significant scientific discoveries, enhancing our understanding of the cosmos.
NASA estimates that Hubble will remain in orbit until at least 2035, allowing ample time to consider future options for its maintenance and enhancement. The telescope continues to produce valuable scientific data, contributing to our knowledge of the universe's structure, evolution, and phenomena. As it operates alongside JWST, Hubble's observations remain crucial for astronomers worldwide.
"We do not see Hubble as being on its last legs," emphasized Clampin, reflecting the agency's confidence in the telescope's ongoing value. The decision to forego an immediate reboost mission underscores NASA's commitment to maximizing Hubble's scientific return while managing risks carefully.
While Hubble faces significant challenges with its aging gyroscopes, NASA's strategic planning and technological innovations ensure that this venerable telescope will continue to provide extraordinary scientific insights for years to come. As Hubble approaches its 35th anniversary, its legacy of discovery and exploration remains as strong as ever.