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NASA partially restored the Hubble Space Telescope to science mode after a software error temporarily halted observations, but engineers continue to study an issue that prevented the telescope’s opening door from closing and a separate issue with Hubble’s main camera.
NASA said Friday that Hubble resumed scientific observations at 8 p.m. EST Thursday (1 a.m. GMT Friday) after going into safe mode on Sunday. Safe Mode is an event in which Hubble places itself in a safe configuration to wait for instructions from the ground.
Hubble entered Safe Mode on Sunday after detecting a software error in the spacecraft’s main computer, NASA said. Ground crews at NASA’s Goddard Space Flight Center in Maryland traced the software problem to code recently uploaded to Hubble to “help compensate for fluctuations in one of its gyroscopes,” NASA said.
Gyroscopes are part of Hubble’s pointing system, use reaction wheels to rotate the telescope towards distant galaxies, stars and planets to collect scientific data and images. Gyroscopes measure the direction and speed of the movement of the spacecraft as it rotates.
Engineers found that the software error that caused Hubble to go into safe mode last weekend involved an improvement that did not allow writing to a specific location in the main computer’s memory, the company said. NASA. Ground crews have removed the suspicious code from the computer to allow Hubble to quickly resume science operations and will update the improvement to upload it back to the spacecraft, officials said.
But NASA continues to study two separate issues that engineers discovered when Hubble was in safe mode.
One concerns the opening door at the top end of the telescope, which failed to close automatically when Hubble went into safe mode on Sunday. The door prevents sunlight from damaging Hubble’s sensitive instruments, and closing the telescope cover during safe mode is supposed to protect the inside of the telescope in case the spacecraft accidentally points at the sun.
NASA closed the door of the opening when space shuttles traveled to Hubble for maintenance missions, but the door was never ordered closed after detecting that the spacecraft’s pointing was moving too close of the sun, the agency said in a statement.
Further analysis by ground crews indicated that the lid remained closed despite commands and power sent to the opening door. Manual controls connected from ground controllers to the main door motor also failed to move the telescope cover, NASA said.
“However, the same commands sent from the ground to his standby motor indicated movement, and that motor is now defined as the main motor. The team is studying options to further reduce the associated risks, ”said NASA.
Engineers are also assessing a “low voltage problem” with the Wide Field 3 camera, Hubble’s latest science camera and most widely used instrument. The error prevents the camera from resuming observations, but Hubble’s other instruments are fully recovered and operational, NASA said.
The famous in-orbit observatory, developed by NASA with the contribution of the European Space Agency, has been maintained and modernized by five space shuttle missions. The last maintenance visit by astronauts aboard Shuttle Atlantis in 2009 installed the Wide Field 3 camera.
With the space shuttles removed, Hubble is in the twilight of its mission. NASA’s next advanced space observatory – the James Webb Space Telescope – is slated to launch in October to expand Hubble’s vision with a larger mirror and a suite of more sophisticated science instruments.
Last year, during virtual celebrations marking the 30th anniversary of Hubble’s launch, mission officials said they expected to get at least five more years of interesting astronomical observations from the long-lived observatory. . Only three of Hubble’s six gyroscopes are still working, and the telescope needs three for regular operations.
This leaves Hubble without redundancy in its gyro system. Engineers have devised ways to track some of the telescope’s observations with a single gyroscope, but this would result in limitations on where Hubble could point when it orbits about 550 kilometers above Earth.
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