The Hubble Space Telescope鈥檚 main camera has been resuscitated after shutting itself down more than two weeks ago. Programme managers say it should resume normal science observations in another week or two.
Hubble鈥檚 most frequently used instrument, the Advanced Camera for Surveys (ACS), uses three 鈥渃hannels鈥� that each act as a camera. All three shut down on 23 September when managers tried to switch power from the Solar Blind Channel to the High Resolution Channel (HRC). A mechanical relay, or switch, flips back and forth to send power to either of the channels.
Managers suspected the switch did actually move as planned but that a piece of fibre or dust was in the way, blocking the electrical contact in the circuit. So on Monday at 1755 EDT (2155 GMT), they flipped the switch back and forth to try to dislodge the debris.
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They received confirmation that the fix had worked at 0540 EDT (0940 GMT) on Tuesday, when the ACS鈥檚 full voltage was detected and the HRC channel in particular showed vital signs again.
鈥淚鈥檓 really happy to say that it was as good an outcome as it possibly could have been,鈥� says David Leckrone, senior project scientist for Hubble at NASA鈥檚 Goddard Space Flight Center in Greenbelt, Maryland, US. 鈥淚t kind of vindicates the leading theory about what the problem was.鈥�
鈥業ntestinal fortitude鈥�
The fix comes as a relief to the team, who had feared that an electronics problem with the HRC would have caused it to lose half its field of view. More worrisome was the concern that toggling the relay to fix the original problem might have created a short circuit, putting the entire ACS out of commission 鈥� though managers later decided such a risk was minimal.
As a result of those fears, programme managers hope to keep the switch where it is. 鈥淗aving gone through this, none of us has the intestinal fortitude to flip it the way we used to flip it,鈥� Leckrone told New 杏吧原创. 鈥淲e鈥檇 like to leave it the way it is and find an alternative way to toggle amongst the three different channels.鈥�
That means the Solar Blind Channel cannot be used until programme managers decide on another way of sending it power, which is expected to take another two weeks or so. And even though the HRC is now receiving power again, engineers will simply monitor it this week to make sure it continues to function smoothly. It is expected to begin scientific observations again early next week.
The ACS is Hubble鈥檚 newest camera 鈥� it was installed in 2002 鈥� but this is not the first time it has shut down. It also stopped working in June 2006 when its original power supply failed; it was brought back online when managers switched to backup power (see Hubble鈥檚 main camera is back at work).
鈥淭hings do fail from time to time,鈥� says Leckrone. 鈥淭hat鈥檚 the reason we鈥檇 love to be able to go up and service Hubble if we can.鈥�
Hubble is expected to stop being able to make science observations in late 2008 unless it is fitted with new batteries and gyroscopes, which would extend its life expectancy until 2013. Within the next month, NASA should announce whether it will send space shuttle astronauts to upgrade the 16-year-old telescope.
