Hibernating instrument on Hubble roused as engineers ponder message problem

A software workaround for an iffy component looms. Sound familiar?

Ever had a component spew garbage and had to bodge around it? Engineers appear to be faced with a similar issue as they continue work to rouse the science instruments of the Hubble Space Telescope from their Safe Mode slumbers.

The good news is that the team might be close to isolating the problem. The bad news is that the finger of blame is hovering over a bit of hardware in the Science Instrument Command and Data Handling Unit. "Specifically," said NASA, "the team is analyzing the circuitry of the Control Unit, which generates synchronization messages and passes them onto the instruments."

NASA is working to resolve an issue that suspended science operations on Hubble.

The team is looking at taking steps to recover the Advanced Camera for Surveys instrument from safe mode to start collecting science with that instrument next week. https://t.co/GGtwDYuIYg

— Hubble (@NASAHubble) November 4, 2021

Why bad news? Because if there is a hardware fault, there is no way to replace the failed component. Engineers will have to work around it using software, possibly with an update to check for the lost messages and compensate for them, thus avoiding other protection software throwing a hissy fit and sending the science instruments into safe mode.

We've all encountered that one weird component in our projects that occasionally does something strange and we end up having to code a bodge to deal with its funny little ways.

The problem is knowing just how often the problem occurs, and to that end the team has resurrected the Near Infrared Camera and Multi Object Spectrometer (NICMOS) instrument, which has been inactive for more than a decade. Some of the functions of NICMOS were replaced by the Wide Field Camera 3 (WFC), installed during the final Space Shuttle servicing mission, STS-125 in 2009.

Although every component on the veteran telescope is precious, bringing up NICMOS represented less of a risk than using an active instrument. It was recovered on 1 November, and no additional synchronisation messages have been lost.

The Advanced Camera for Surveys (ACS) is next in line, but the team is proceeding very cautiously for fear of "additional stresses" on the hardware. "ACS was selected as the first instrument to recover as it faces the fewest complications should a lost message occur," said NASA.

All eyes will be on those synchronisation messages and the frequency of the problem. Once the scale and source of the issue is understood, any required software changes can be sketched out and a plan made for resuming the collection of science data from Hubble's remaining instruments. ®