After completing a series of tests and carefully considering options, NASA announced that work is underway to transition its Hubble Space Telescope to operate using a single gyroscope. While the telescope entered safe mode on May 24, where it will remain until the work is completed, this change will allow Hubble to continue exploring the secrets of the universe throughout this decade and the next, without the majority of its observations being affected. .
Of the six gyroscopes currently on the spacecraft, three remain active. They measure the rotation speeds of the telescope and are part of the system that determines and controls the direction in which the telescope points. Over the past six months, one gyroscope in particular has returned increasingly faulty readings, causing the spacecraft to enter safe mode several times and suspend scientific observations while the telescope awaits further instructions from the ground.
This gyroscope is experiencing “saturation”, where indicates the maximum spin rate value possible regardless of how fast the spacecraft is spinning. Although the team has been able to repeatedly reset the gyroscope’s electronics to normal readings, the results have only been temporary before the problem reappeared as it did in late May.
To return to consistent scientific operations, NASA is transitioning the spacecraft to a new operating mode it had long considered: Hubble will operate with a single gyroscope, while keeping another gyro available for future use. The spacecraft had six new gyroscopes installed during the fifth and final space shuttle servicing mission in 2009. To date, three of those gyroscopes remain operational, including the gyroscope currently experiencing problems, which the team will continue to monitor.
Hubble uses three gyroscopes to maximize efficiency, but you can continue to make scientific observations with a single gyroscope. NASA first developed this plan more than 20 years ago, as the best operational mode to extend the life of Hubble and allow it to provide consistent science with fewer than three gyroscopes operating. Hubble previously operated in dual-gyro mode, which is insignificantly different from single-gyro mode, between 2005 and 2009. Single-gyro operations were demonstrated in 2008 for a brief period with no impact on the quality of scientific observation.
While scientific observations continue to be made in gyroscope mode, some minor limitations are expected. The observatory will need more time to pivot and set a scientific goal and you won’t have as much flexibility as to where you can observe at any given time. It also won’t be able to track moving objects closer than Mars, although these are rare targets for Hubble.
The transition involves reconfigure the spacecraft and the Earth system, as well as evaluate the impact on future planned observations. The team hopes to resume scientific operations again in mid-June. Once in gyroscope mode, NASA anticipates that Hubble will continue to make new cosmic discoveries alongside other observatories, such as the agency’s James Webb Space Telescope and the future Roman Nancy Grace Space Telescope, for years to come.
Launched in 1990, Hubble has more than doubled its useful life planned and has been observing the universe for more than three decades, recently celebrating its 34th anniversary.
