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NASA has recovered the Kepler Space Telescope from 'emergency mode'

81 points by wanderer42 11y ago

miander 11y ago
Is there a more detailed/technical article available?
- LeifCarrotson 11y ago
  After a few links in the article pointing to other Verge articles, I found this: http://www.nasa.gov/feature/mission-manager-update-kepler-recovered-from-emergency-and-stable http://www.nasa.gov/feature/mission-manager-update-kepler-re...
Tzunamitom 11y ago
CTRL-ALT-DELETE?
pc86 11y ago
Can someone explain why emergency mode is the most fuel-intensive despite being the lowest powered?
- dtparr 11y ago
  Stolen shamelessly from the Ars Technica comment that explained it to me: http://arstechnica.com/science/2016/04/kepler-exits-emergency-mode-re-establishes-full-communication/?comments=1&post=30987657 http://arstechnica.com/science/2016/04/kepler-exits-emergenc... >Normally Kepler (in K2 mode) uses the pressure from sunlight combined with the two remaining reaction wheels to maintain orientation. It still does need periodic thruster usage but the heavy lifting is done by solar pressure and reaction wheels which makes the propellent usage very efficient. However it is a complicated and precarious balancing act. It needs full instrumentation, computer operation, and periodic updates from Earth to work. >When it goes into emergency mode it falls back on 100% station keeping thrusters because that is simpler although far more expensive in terms of fuel. They don't know exactly why it went into emergency mode but for whatever reason Kepler believed it could not maintain orientation without it. >In emergency mode it has to expand propellent because without some station keeping it would begin to tumble uncontrollably. If you have a spacecraft millions of kms away from Earth, tumbling out of control with its communication array no longer pointed at Earth you will probably never regain control. So it is a last ditch effort to maintain proper orientation on the hope that command & control update can fix the problem. It begins "looking" for an command & control signal from Earth (using propellent to orient the spacecraft). If/when it finds it, it then tries to keep that orientation using 100% station keeping thrusters regardless of fuel consumption. It will continue to do so until standard operation is restored or it runs out of fuel.
  - pc86 11y ago
    Perfect explanation, thank you!
Altaer 11y ago
I work on software for a few satellites (not Kepler) and they have gone into an emergency or safe mode a couple times over their long lifetime. None of those times ended up being because of a serious problem. While I am interested to hear back on what exactly tripped the emergency mode, I think the main sad news here is the loss of the finite supply of fuel on board, which will ultimately shorten Kepler's operational lifetime.
cyphar 11y ago
Kepler is definitely one of the most important space telescopes that we have (and will have for the foreseeable future). It has both long and short cadence data for many very interesting targets over 3 month periods. TESS will only give us data for one month on each arc of the sky it is scanning (although, it means we'll get a full picture of the sky) but it won't observe the K2 field (the ecliptic plane). It's such a shame to see it losing so much fuel and energy.

81 points by wanderer42 11y ago

miander 11y ago

Is there a more detailed/technical article available?

LeifCarrotson 11y ago
After a few links in the article pointing to other Verge articles, I found this: http://www.nasa.gov/feature/mission-manager-update-kepler-recovered-from-emergency-and-stable http://www.nasa.gov/feature/mission-manager-update-kepler-re...

Tzunamitom 11y ago

CTRL-ALT-DELETE?

pc86 11y ago

Can someone explain why emergency mode is the most fuel-intensive despite being the lowest powered?

dtparr 11y ago
Stolen shamelessly from the Ars Technica comment that explained it to me: http://arstechnica.com/science/2016/04/kepler-exits-emergency-mode-re-establishes-full-communication/?comments=1&post=30987657 http://arstechnica.com/science/2016/04/kepler-exits-emergenc... >Normally Kepler (in K2 mode) uses the pressure from sunlight combined with the two remaining reaction wheels to maintain orientation. It still does need periodic thruster usage but the heavy lifting is done by solar pressure and reaction wheels which makes the propellent usage very efficient. However it is a complicated and precarious balancing act. It needs full instrumentation, computer operation, and periodic updates from Earth to work. >When it goes into emergency mode it falls back on 100% station keeping thrusters because that is simpler although far more expensive in terms of fuel. They don't know exactly why it went into emergency mode but for whatever reason Kepler believed it could not maintain orientation without it. >In emergency mode it has to expand propellent because without some station keeping it would begin to tumble uncontrollably. If you have a spacecraft millions of kms away from Earth, tumbling out of control with its communication array no longer pointed at Earth you will probably never regain control. So it is a last ditch effort to maintain proper orientation on the hope that command & control update can fix the problem. It begins "looking" for an command & control signal from Earth (using propellent to orient the spacecraft). If/when it finds it, it then tries to keep that orientation using 100% station keeping thrusters regardless of fuel consumption. It will continue to do so until standard operation is restored or it runs out of fuel.
- pc86 11y ago
  Perfect explanation, thank you!

Altaer 11y ago

I work on software for a few satellites (not Kepler) and they have gone into an emergency or safe mode a couple times over their long lifetime. None of those times ended up being because of a serious problem. While I am interested to hear back on what exactly tripped the emergency mode, I think the main sad news here is the loss of the finite supply of fuel on board, which will ultimately shorten Kepler's operational lifetime.

cyphar 11y ago

Kepler is definitely one of the most important space telescopes that we have (and will have for the foreseeable future). It has both long and short cadence data for many very interesting targets over 3 month periods. TESS will only give us data for one month on each arc of the sky it is scanning (although, it means we'll get a full picture of the sky) but it won't observe the K2 field (the ecliptic plane). It's such a shame to see it losing so much fuel and energy.