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Hubble has serious data problems – Digi.no

Hubble is equipped with several computers that fit different tasks and functions. One of these is a “payload computer” that controls Hubble’s instruments and systems. On the evening of Sunday 13 June, Hubble’s main computer sent a message to the ground crew that it no longer received a response from the payload computer.

Thus, the entire telescope was put in safe mode, and this has been the case for over a week, without a solution yet in sight.

NASA tried to restart the payload computer the next day, without success. They then wondered if the problem could be due to one of the machine’s memory modules having failed. Such memory modules can be damaged by cosmic radiation, and Hubble has been in space for over 30 years. It was therefore not unlikely that this could be the cause, but when NASA on Wednesday 16 June tried to switch to one of the three memory modules the payload computer has in reserve, it also failed.

Must in the worst case cancel

The next day, NASA once again tried to make both of the mentioned memory modules work, and in addition send more diagnostic information down to the ground stations, but this was not crowned with success either.

The memory modules in question are of the CMOS type (“Complementary Metal-Oxide Semiconductor”) and do not have a capacity of more than 64 Kb each.

The latest update from NASA came on June 18, and did not say much more than that they are still working on the case. In the meantime, scientific observations must wait or, in the worst case, be canceled. Observation time on Hubble is sought after and planned long in advance, and projects are queuing up to use the space telescope.



Made in the 80’s

The failed computer is of the type NSSC-1 (“NASA Standard Spacecraft Computer-1”) and was developed to make it cheaper and easier to build and maintain spacecraft by standardizing computers. Planning began as early as 1974, and it has since been used in a number of probes and vessels throughout the 80s and 90s.

Fortunately, Hubble has an extra NSSC-1 in reserve, in case the first one should fail. It is not known if NASA has yet tried to switch to the reserve unit.

Hubble’s mainframe computer was originally a DF-224 from Rockwell Autonetics with three processors, two of which were in reserve. It measured about 45 x 45 x 30 cm and weighed around 50 kg. The clock speed was 1.25 MHz. The first time Hubble was maintained after launch, the mainframe had a co-processor installed in the form of a 15 MHz Intel 80386 with an 80387 math co-processor. In 1999, both were replaced by a 25 MHz Intel 80486, something that seemed old-fashioned even then. However, it was a huge improvement: Not only was the speed increased by 20 times, it also got six times as much memory, in addition to being able to use far more modern programming languages ​​than before.

In addition to the payload computer NSSC-1 and the mainframe, Hubble also has a number of different smaller processing units connected to the various instruments.

The sequel may be delayed once again

Hubble was last physically maintained in 2009, but since the space shuttle program ended, NASA has not had the finances, will or ability to do so again. Hubble’s orbit 600 km above the earth’s surface is at the very limit of how far the space shuttle could reach, and no spacecraft with a similar range is in use today.

NASA has instead chosen to focus on JWST, often called Hubble’s successor, which has been under planning, development and construction for a very long time. It was supposed to be shot up in the autumn, however now appears to be further delayed.



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