NASA on Hubble Space Telescope Restoration: Possible Read/Write Problem but Equipment "In Good Health"

NASA continues to diagnose the issue with the payload computer onboard the Hubble Space Telescope - with its recent tests last June 23 and 24 revealing that the telescope and its science instruments are still in "good health" and in a "safe configuration."

The Hubble Space Telescope made headlines over the past week as its payload computer stopped on June 13, effectively halting all collection of science data on the spacecraft.

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Isolating the Payload Computers Issue

In its June 25 news release, NASA explains that the Hubble Space Telescope carries two payload computers, one of which is a backup. These payload computers are housed in the Science Instrument and Command and Data Handling (SI C&DH) unit. Additionally, different parts make up the payload computers as a whole, which includes the following:

A Central Processing Module, or CPM, processes the commands coordinating and controlling the science instruments onboard.
A Standard Interface, or STINT, connects the CPM and other components and allows them to communicate.
A communications bus that contains the lines transmitting signal and data between parts of the payload computers.
A memory module that keeps operational commands to the science instruments; three additional memory modules serve as backup.

NASA said that its June 23 and 24 tests included powering up the backup payload computer for the first time. Their tests revealed that combinations of these pieces of hardware - a mix of parts from the main and the backup payload computers - showed the same error of unsuccessful attempts to write or read commands from memory.

Through these tests, NASA thinks that it is "highly unlikely" that the problem is with all the individual hardware tested, which prompted them to look at other parts, such as the Command Unit/ Science Data Formatter also within the SI C&DH unit. The Command Unit formats and transmits data to certain locations, such as the science instruments, while the Science Data Formatter converts data gathered by the science instrument to recognizable formats before being transmitted into the ground station.

Science Instruments on the Hubble Space Telescope

According to Hubblesite, the dedicated website for the spacecraft, the Hubble Space Telescope, was originally designed to hold six different science instruments. Its current suite of instruments includes the Wide Field Camera 3 (WFC3), which gives the telescope better imaging capabilities by observing ultraviolet and infrared light in addition to the visible light spectrum. Fitted in a high-resolution, wide-view vision system, the main camera onboard the Hubble has provided NASA with some of its most spectacular images.

Also, in processing the ultraviolet light that it captures, the telescope also uses the Cosmic Origins Spectrograph (COS) to capture radiation and break it into parts that can be further studied in detail. It is often used in tracking and identifying distant light sources like stars or quasars - the latter being an extremely luminous object that often contains a black hole surrounded by massive amounts of gas.

Aside from the COS, the Hubble Space Telescope also has a Space Telescope Imaging Spectrograph (STIS) and other science instruments such as the Advanced Camera for Surveys and the Near Infrared Camera and Multi-Object Spectrometer (NICMOS).