Hubble’s wide field camera returns to operation
Though the Hubble Space Telescope returned to science operations on March 12th after going into safe mode, its wide field camera did not.
Engineers however now report that they have successfully restored the camera to operations as well. The reason for the delayed restoration exemplifies Hubble’s aging status.
Analysis showed that voltage levels in WFC3 power supplies have slowly decreased over time as their electronics aged. The electronics experience colder temperatures when the hardware is turned off in safe mode. This factor coupled with the power the instrument components draw as they are turned back on contributed to the small voltage fluctuation that suspended WFC3 recovery operations. Further detailed analysis indicated that it would be safe to slightly reduce the low voltage limit to avoid a future suspend, and it would be safe to recover the instrument to its science state.
The instrument has now been safely recovered. Standard calibration of the instrument and other pre-observation activities will be conducted this week.
All the telescope’s equipment has been adjusted in recent years to deal with the varying ages of its instruments and its main structure. For example, this wide field camera was installed during the last shuttle serving mission in 2009, and is therefore one of Hubble’s newest components. It however is now more than a decade old, and thus needs careful handling to function properly.
Other components are far older, such as the primary motor to open and close the telescope’s “lens cap”. That failed during this safe mode, forcing engineers to switch to a back up motor to control the cap. Whether they can recover that primary motor is presently unclear, though unlikely.
Expect more such issues in the coming years.
On Christmas Eve 1968 three Americans became the first humans to visit another world. What they did to celebrate was unexpected and profound, and will be remembered throughout all human history. Genesis: the Story of Apollo 8, Robert Zimmerman's classic history of humanity's first journey to another world, tells that story, and it is now available as both an ebook and an audiobook, both with a foreword by Valerie Anders and a new introduction by Robert Zimmerman.
The ebook is available everywhere for $5.99 (before discount) at amazon, or direct from my ebook publisher, ebookit. If you buy it from ebookit you don't support the big tech companies and the author gets a bigger cut much sooner.
The audiobook is also available at all these vendors, and is also free with a 30-day trial membership to Audible.
"Not simply about one mission, [Genesis] is also the history of America's quest for the moon... Zimmerman has done a masterful job of tying disparate events together into a solid account of one of America's greatest human triumphs."--San Antonio Express-News
Though the Hubble Space Telescope returned to science operations on March 12th after going into safe mode, its wide field camera did not.
Engineers however now report that they have successfully restored the camera to operations as well. The reason for the delayed restoration exemplifies Hubble’s aging status.
Analysis showed that voltage levels in WFC3 power supplies have slowly decreased over time as their electronics aged. The electronics experience colder temperatures when the hardware is turned off in safe mode. This factor coupled with the power the instrument components draw as they are turned back on contributed to the small voltage fluctuation that suspended WFC3 recovery operations. Further detailed analysis indicated that it would be safe to slightly reduce the low voltage limit to avoid a future suspend, and it would be safe to recover the instrument to its science state.
The instrument has now been safely recovered. Standard calibration of the instrument and other pre-observation activities will be conducted this week.
All the telescope’s equipment has been adjusted in recent years to deal with the varying ages of its instruments and its main structure. For example, this wide field camera was installed during the last shuttle serving mission in 2009, and is therefore one of Hubble’s newest components. It however is now more than a decade old, and thus needs careful handling to function properly.
Other components are far older, such as the primary motor to open and close the telescope’s “lens cap”. That failed during this safe mode, forcing engineers to switch to a back up motor to control the cap. Whether they can recover that primary motor is presently unclear, though unlikely.
Expect more such issues in the coming years.
On Christmas Eve 1968 three Americans became the first humans to visit another world. What they did to celebrate was unexpected and profound, and will be remembered throughout all human history. Genesis: the Story of Apollo 8, Robert Zimmerman's classic history of humanity's first journey to another world, tells that story, and it is now available as both an ebook and an audiobook, both with a foreword by Valerie Anders and a new introduction by Robert Zimmerman.
The ebook is available everywhere for $5.99 (before discount) at amazon, or direct from my ebook publisher, ebookit. If you buy it from ebookit you don't support the big tech companies and the author gets a bigger cut much sooner.
The audiobook is also available at all these vendors, and is also free with a 30-day trial membership to Audible.
"Not simply about one mission, [Genesis] is also the history of America's quest for the moon... Zimmerman has done a masterful job of tying disparate events together into a solid account of one of America's greatest human triumphs."--San Antonio Express-News
OT: story linked from Drudge today https://www.accuweather.com/en/space-news/massive-piece-of-space-junk-tossed-from-iss-sets-record/916013
In regard to jetitisoning something from the ISS and sending it back to earth … if a person throws a ball from the ISS towards the Earth, would the ball stay in orbit? Or would it move at the rate and direction it was thrown, and pretty quickly fall to earth? ( which I guess also begs the question, can you throw a fastball on the ISS? )
If you throw a ball from ISS directly towards the Earth, remember that the ISS (and hence the ball) is traveling at some 17,000 mph in orbit. Assuming you are a major league pitcher and throw the ball at 100mph at the earth, the ball’s resultant velocity will be the vector sum of 17,000 horizontally and 100 vertically. It will just assume a slightly different orbit than the ISS.
“… the ball’s resultant velocity will be the vector sum of 17,000 horizontally and 100 vertically. It will just assume a slightly different orbit than the ISS. …”
I follow that the ball is orbiting the earth, just as the ISS is. Just do not understand why the ball does not not continue moving toward the earth at 100 mph.
Steve / Andi
-> I believe this is very enlightening. Manley discusses this exact situation in the first 5 minutes. (and, check out the math at around the 3:40 mark.)
((I can barely conceptualize orbital mechanics myself!))
“The Most Confusing Things About Spacecraft Orbits”
Scott Manley
May 2018
https://youtu.be/i5XPFjqPLik
11:07
Steve Richter asked: “if a person throws a ball from the ISS towards the Earth, would the ball stay in orbit?”
Scott Manley’s video was the first thing that came to my mind, but wayne beat me to it. Keep in mind that every maneuver in space only changes the orbit. Manley’s video shows that the original downward motion of the ball turns into an upward motion half an orbit later. That is a good way to think about orbits when you don’t want to do the math.
The reason for a ball to reach the Earth would be for the new orbit to have a low point, perigee, that is inside the atmosphere or that intersects the surface. As Manley pointed out, this would be about 1/4 orbit away from the point where the ball was thrown.
There is a lot that is counterintuitive about orbital mechanics, making space navigation even trickier than Earth-bound navigation. If you view the video Manley references early on, you will get a little more information, specifically about throwing things in the retrograde direction, against the direction of the orbital motion.
https://www.youtube.com/watch?v=cxNJoaBLLNM (8 minutes, “Could An Astronaut Throw Something From Orbit To Earth?”)
thanks for the Scott Manley link. Fascinating. Still do not understand.
Maybe it helps me to think of a space craft travelling from Earth to Mars. But the straight line course of the craft takes it past Mars. As it passes Mars, the straight line course will be bent by Mar’s gravity. The further from Mars as it passes by, the less the course will be affected. And the closer the craft is to Mars as it passes by, the more the course will be bent. Too close and it starts to orbit, but then flings out at close to a 90 degree angle? But far enough away as the craft passes Mars and it will be captured into the orbit of the planet?
Back to the ball and the space craft … if a ball is thrown from the craft at a 90 degree angle, that would put the ball in either a closer or further out orbit as both the craft and the ball pass by Mars.
Not asking for an answer. Just thinking out loud.
Steve Richter,
Thinking in straight lines is misleading. Even traveling from Earth to Mars, the Sun’s gravity curves the path into an ellipse around the Sun. It adds to the complexity of the calculation to reach Mars.
When something approaches from far away and is not in orbit around the planet, it requires a change in velocity in order to enter into an orbit around Mars. For our probes, this often occurs due to firing thrusters, but it can also happen by using Mars’s atmosphere to slow down to enter into an elliptical orbit. Without this change, the object would remain in a hyperbolic orbit, which does not go around the planet, in which it comes from far away and leaves to go far away again, just in a different direction.
In this video, Astronaut Chris Hadfield gives a basic lesson in orbits, with the second part talking about docking with a space station:
https://www.youtube.com/watch?v=PooFvQEN4n8 (16 minutes)