Second Space Telescope Shuts Down, NASA Says

  • Second Space Telescope Shuts Down, NASA Says

Second Space Telescope Shuts Down, NASA Says

NASA said the gyro is reporting rotation rates "orders of magnitude higher than they actually are", although it did appear to be properly tracking the telescope's movements.

This is similar to a speedometer on your auto continuously showing that your speed is 100 miles per hour faster than it actually is; it properly shows when your vehicle speeds up or slows down, and by how much, but the actual speed is inaccurate.

If the outcome indicates that the gyro is not usable, Hubble will resume science operations in an already defined "reduced-gyro" mode that uses only one gyro. In this high mode it may be possible to subtract out a consistent large offset to get an accurate reading. The extremely high rates now being reported exceed the upper limit of the gyro in this low mode, preventing the gyro from reporting the spacecraft's small movements.

Scientists turned on a replacement gyro, but the backup didn't perform as hoped.

It is the second technical problem that affects an American space telescope, as for some days something similar has happened to Hubble, which, having lost one of its orientation gyros, has also been forced to operate in a "safe mode", stopping the observations sky's. The spacecraft remains in this configuration until ground control can correct or compensate for the issue.

As well, the team says that all of Chandra's instruments are "safe", and that "all systems functioned as expected". The spacecrafts' gyroscopes are small spinning wheels that work to rotate the telescope and keep it stable while observing.

To meet the stringent pointing requirements necessary to study far-off astronomical objects and obtain groundbreaking science data, Hubble's gyros are extremely accurate. For optimal efficiency Hubble needs to have at least three gyros in working condition.

Built with multiple redundancies, Hubble had six new gyros installed during Servicing Mission-4 in 2009.

When questioned about keeping one of the last two gyros switched off, she said the standard instruction is to switch to one gyro mode when only two remain active.

"Chandra is 19 years old, which is well beyond the original design lifetime of 5 years", NASA explained. Later in 2001, NASA extended its lifetime to 10 years. The current situation has raised questions about its age but its replacement James Webb Space Telescope is not likely to launch till 2021 so Hubble has to be carefully managed till then.