Hate to burst your Hubble: Science stops as boffins scramble to diagnose gyro problem Space-watchers have been nervously watching that bit of space occupied by the Hubble Space Telescope as NASA tries to diagnose a problem with its gyroscopes. The Register first noticed a questionmark over Hubble's health during the weekend, when Michigan State University astronomer Jay Strader tweeted rumours that it was in …
Could a private sponsor not finance another repair mission, using SpaceX and a Dragon 2 capsule. It should be a bit cheaper than a Shuttle mission, and then they could rename it for PR purposes.
I propose a chewing gum manufacturer, giving us the Hubba Bubba Space Telescope.
"Could a private sponsor not finance another repair mission, using SpaceX and a Dragon 2 capsule. It should be a bit cheaper than a Shuttle mission, and then they could rename it for PR purposes"
It's a nice idea but one which could cost $1 billion+.
Back in 2012, the US National Reconnaissance Office donated two space telescopes to NASA, one of which has been allocated to the WFIRST project, and I'd like to like to see any spare funds spent on turning the second donated telescope into an optical wavelength Hubble replacement instead (despite the hype, the James Webb Space Telescope isn't a like for like replacement for Hubble not least because the JWST operates primarily at near and mid infrared wavelengths).
"and I'd like to like to see any spare funds spent on turning the second donated telescope into an optical wavelength Hubble replacement instead "
One of the proposals for the 2nd one is to do what you say and turn it into an optical telescope, but put it in mars orbit.
That way it could take high resolution pictures of the surface of Mars and also take pictures of space.
These 2 telescopes have a shorter focal length then Hubble does so they won't be able to see as far into deep space as Hubble can, but they can take better pictures of nearer stuff then Hubble can.
The focal length has nothing to do with how far you can see, but more about the field of view and resolution you get with a given sensor.
Example:
A full frame DSLR camera with a 100mm lens gives an approximate horizontal field of view of 20 degrees
If you replace the 100mm lens with a 50mm one your field of view will double and at the same time the resolution will be halved if using the same sensor.
The theoretical resolution of a telescope is not affected by the facal length of the telescope but by its diameter. Hubble has a theoretical maximum resolution of about 0.05" while in practice the resolution achieved with most of the sensors is about twice that 0.1"
If I recall correctly the telescopes they got were rumored to be spares for KH-11 telescopes. so they should probably be 2.4 meter diameter telescopes which is identical to that of hubble and it should thus be able to achieve more or less the same resolution.
"These 2 telescopes have a shorter focal length then Hubble does so they won't be able to see as far into deep space as Hubble can."
I didn't realise they made telescopes with parsec focal lengths! But I guess that's what makes astronomy so tricky: focusing light from objects so far away.
*Sigh* Stars are "prefocused" (they're point sources at infinity) and so focal length has bugger all effect on how far a telescope can see. It does look as if these scopes won't see as far as Hubble, but that's because they're not designed to be cooled [SOURCE] and so won't be able to separate (infra)red-shifted starlight from thermal noise. However the focal length will give it a much wider field of view than Hubble and it will be able to see fainter objects at much closer distances [ibid].
"I propose a chewing gum manufacturer, giving us the Hubba Bubba Space Telescope."
Or, if one prefers a chewing gum sponsor, then perhaps the more assonant Dubble Bubble Hubble Space Telescope ©®™.
"Could a private sponsor not finance another repair mission, using SpaceX and a Dragon 2 capsule."
The Dragon doesn't have a robotic arm to grab onto the HST, and using attitude thrusters up close is a no-no because the exhaust could/would contaminate the optics.
Sadly Hubble was designed to be repaired by the Shuttle only.
Let's hope that they fix it.
Gyros seem to be a perennial problem, I suppose that since they have to move (spin) all the time they suffer wear & bearings break.
One thing that I just learned is that the gyros are used to detect Hubble's orientation, and that reaction wheels are used to move/rotate it.
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>didn't replace the gyro's with the ring laser sort
Lifetime concerns, Nasa likes to use kit that has been around for 30+ years before relying on it.
It's not clear that LRGs (or at least early 90s versions) had the long term stability of a spinning gyro and
power requirements for early LRGs were high.
Space-qualified high-stability radiation-hard diode lasers weren't well proven, Hubble is in a terrible orbit for radiation
Since it also has magnetic field sensors and fine guidance cameras for precise pointing and after 30+ years they have good models of its dynamics I suspect you can do a lot without a gyro platform. The gyros were mainly to give an accurate absolute orientation for slewing to a new target.
Apparently bits of metal brought together in a vacuum don't know they are separate parts.
"I am astounded that someone thought using pressurized oxygen was a good idea"
The link cited above <https://www.spacetelescope.org/about/general/gyroscopes/> says that it was "oxygen pressurized air". I'm sure there was a sound engineering argument for using oxygen as the gas to maintain pressurisation but clearly in this case reality had different ideas about what's best.
I've had a look but I can't find an on-line source for this, but I recall reading that the recently launched ESA Aeolus satellite had trouble in development due to the laser causing optical surfaces to darken in vacuum tests and the solution was to install an oxygen source to leak out a wee bit of the stuff to oxidise whatever it was causing the problem.
<https://www.gim-international.com/content/news/esa-s-aeolus-lidar-equipped-wind-satellite-sent-into-orbit>
I remember reading an article about ring laser gyroscopes in Scientific American in the 1970s - noteworthy because some of the photos were censored (little black bars over parts of the image) for security reasons. RLGs, fibre-optic gyros etc. must have come on a bit since then. Do they use optical or mechanical gyros on Hubble???
"Mechanical as those are inherently stable (while spinning), optical gyroscopes need a feedback loop and continuous adjustment."
Optical ones are small enough that you can put a dozen in the space of one mechanical one and modern mechanical ones are smaller than the 1970s-era ones that were originally fitted, so you could make a judgement call and fit stupid levels of redundancy in a replacement package.
None of that matters if you can't make a service call to replace the things.
This doesn't sound like it's too serious yet. A gyro they knew was near to failing has failed, and one of the reserve ones they could have powered up to replace it isn't performing up to standard. Seems like they're keeping things in safe mode while they try to diagnose the problem and sort it, but they do have other gyros in reserve.
Yes, it's puzzling. I don't think I've ever seen anything quite like this before. I would recommend that we put the unit back in operation and let it fail. It should then be a simple matter to track down the cause. We can certainly afford to be out of communication for the short time it will take to replace it.
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