Stanford professor explains how NASA might revive the Kepler space telescope

May 16, 2013 by Bjorn Carey
Artist's composite of the Kepler spacecraft Credit: NASA

(Phys.org) —Scott Hubbard, a consulting professor of aeronautics and astronautics, helped guide the Kepler mission when he served as director of NASA Ames Research Center. He explains how NASA might bring the planet-hunting spacecraft back online.

NASA officials announced Wednesday, May 15, that the Kepler space telescope – the agency's primary instrument for detecting planets beyond our solar system – had suffered a critical failure and could soon be shut down permanently.

Scott Hubbard, a consulting professor of at Stanford's School of Engineering, served as director of NASA Ames Research Center during much of the building phase of the Kepler . He also worked on the project alongside William Borucki, the Kepler science principal investigator at Ames and the driving force behind the effort, for the decades leading up to formal approval of the mission.

The Kepler spacecraft's photo-detector array registers more than 100,000 stars at a time, Hubbard said, and in order to detect exoplanets (planets orbiting stars outside our solar system), the telescope must remain extremely steady so that the stars do not wander across the optics. A series of four gyroscope-like reaction wheels whir within the telescope to hold its gaze. At least three must be functioning to keep Kepler stable. One failed about a year ago and was shut off, and NASA scientists announced Wednesday, May 15, that a second wheel was no longer operating and that Kepler had paused operations.

In a conversation with Stanford News Service, Hubbard explained the possible ways that NASA could bring the spacecraft back online, and what will do next if that's not possible.

How big of a loss will it be if the Kepler space telescope can't be repaired?

The science returns of the have been staggering and have changed our view of the universe, in that we now think there are planets just about everywhere.

It will be very sad if it can't go on any longer, but the taxpayers did get their money's worth. Kepler has, so far, detected more than 2,700 candidate exoplanets orbiting distant stars, including many Earth-size planets that are within their star's habitable zone, where water could exist in liquid form.

Kepler has done what the program managers said it would do, and that is to give us an inventory of extrasolar planets. It completed its primary observation phase, and had entered its extended science phase. We're already in the gravy train period – there's still a year and a half's worth of data in the pipeline that scientists will analyze to identify other candidate planets, and there will continue to be Kepler science discoveries for quite some time.

How might NASA engineers go about getting Kepler functional again?

There are two possible ways to salvage the spacecraft that I'm aware of. One is that they could try turning back on the reaction wheel that they shut off a year ago. It was putting metal on metal, and the friction was interfering with its operation, so you could see if the lubricant that is in there, having sat quietly, has redistributed itself, and maybe it will work.

The other scheme, and this has never been tried, involves using thrusters and the solar pressure exerted on the solar panels to try and act as a third reaction wheel and provide additional pointing stability. I haven't investigated it, but my impression is that it would require sending a lot more operational commands to the spacecraft.

If neither of these options works, Kepler is still an amazing space instrument. Could it conduct other types of experiments?

People have asked about using it to find near-Earth objects, or asteroids. Kepler carries a photometer, not a camera, that looks at the brightness of stars, and so its optics deliberately defocus light from stars to create a nice spread of light on the detector, which is not ideal for spotting asteroids.

Whether or not it could function as a detector for asteroids is something that would have to be studied, but since it wasn't built as a camera, I would say that I'm skeptical. That said, certainly between Ames Research Center and the Jet Propulsion Laboratory, they've got the best people in the world working on it.

What's next for exoplanet hunters?

As I said earlier, there is still a year and a half's worth of data in the pipeline to analyze to identify candidate planets, so there are still discoveries to be made.

It's important to make clear, though, that in the original queue of missions aimed at finding life elsewhere, a mission like Kepler was a survey mission to establish the statistical frequency of whether these planets are rare or common. It lived the length of its prime mission, and was extremely successful during that time at achieving this goal. It has paved the way for additional missions, such as TESS – Transiting Exoplanet Survey Satellite – and TPF – Terrestrial Planet Finder – which will continue the search for Earth-like exoplanets in the near future.

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zorro6204
1.2 / 5 (20) May 16, 2013
". . . the taxpayers did get their money's worth . . . "

Did we? Because, and I hate to say it, this has been a complete waste of time. Why? Because 50 years from now, or even 10, this same mission will cost a pittance compared to the present cost, due to the advances we'll make in the meantime, and THAT is where the money should be going, technique, not practice. Relax, these planets aren't going anywhere, we have time. We need to learn to spend our limited resources more efficiently.
islatas
5 / 5 (8) May 16, 2013
What is our motivation to make these advances if we never use them? At what point are we advanced and efficient enough that it's ok with you to proceed? I sure hope you typed this on someone else's device. We all know electronics advance all the time and spending money on one now is a total waste.
islatas
5 / 5 (7) May 16, 2013
I really hope this mission can be resurrected. It has been incredibly exciting and has stirred the imaginations of adults and children alike. Planets are near everywhere. This mission will be responsible for the spark that influences many people to consider science as a career. It's a model mission for sure!
Feldagast
1.4 / 5 (11) May 16, 2013
Send up a repair team on the shuttle, oh right they were mothballed. Wait let's send up its replacement to fix it, oh right we never replaced the shuttles. Maybe we can pay the Russians to fix it.
Q-Star
3.8 / 5 (10) May 16, 2013
Send up a repair team on the shuttle, oh right they were mothballed. Wait let's send up its replacement to fix it, oh right we never replaced the shuttles. Maybe we can pay the Russians to fix it.


And a shuttle, or a fleet of them, would fix it how?

What would these Russian repairmen use to go fix it?
TopherTO
4.6 / 5 (10) May 16, 2013
Send up a repair team on the shuttle, oh right they were mothballed. Wait let's send up its replacement to fix it, oh right we never replaced the shuttles. Maybe we can pay the Russians to fix it.


Unlike Hubble, we can't reach it by shuttle it orbits the sun not the Earth.
Telekinetic
3.2 / 5 (9) May 16, 2013
". . . the taxpayers did get their money's worth . . . "

Did we? Because, and I hate to say it, this has been a complete waste of time. Why? Because 50 years from now, or even 10, this same mission will cost a pittance compared to the present cost, due to the advances we'll make in the meantime, and THAT is where the money should be going, technique, not practice. Relax, these planets aren't going anywhere, we have time. We need to learn to spend our limited resources more efficiently.

I use the same logic before buying a new TV. Now, I still watch my B&W Zenith with a "rabbit ears" antenna because I'll be dad-burned if I get stuck with this year's newfangled set .
Neinsense99
3.2 / 5 (9) May 17, 2013
". . . the taxpayers did get their money's worth . . . "

Did we? Because, and I hate to say it, this has been a complete waste of time. Why? Because 50 years from now, or even 10, this same mission will cost a pittance compared to the present cost, due to the advances we'll make in the meantime, and THAT is where the money should be going, technique, not practice. Relax, these planets aren't going anywhere, we have time. We need to learn to spend our limited resources more efficiently.


In what distorted reality do people spend huge amounts of money and time perfecting techniques and tools without testing to see that there actually exists something to use the end product on? In which people want to spend their lives building things that they will not live to see used? Where no one needs to check to see if they are going down the right path? In which politicians that control funding don't want results during their term?
jsdarkdestruction
4.3 / 5 (6) May 17, 2013
". . . the taxpayers did get their money's worth . . . "

Did we? Because, and I hate to say it, this has been a complete waste of time. Why? Because 50 years from now, or even 10, this same mission will cost a pittance compared to the present cost, due to the advances we'll make in the meantime, and THAT is where the money should be going, technique, not practice. Relax, these planets aren't going anywhere, we have time. We need to learn to spend our limited resources more efficiently.

Kepler IS/WAS an advance we made, right now, in the present. how can we go further and advance in the future without doing so in projects like this in the meantime first?
alfie_null
5 / 5 (5) May 17, 2013
". . . the taxpayers did get their money's worth . . . "

Did we? Because, and I hate to say it, this has been a complete waste of time. Why? Because 50 years from now, or even 10, this same mission will cost a pittance compared to the present cost, due to the advances we'll make in the meantime, and THAT is where the money should be going, technique, not practice. Relax, these planets aren't going anywhere, we have time. We need to learn to spend our limited resources more efficiently.

By that logic, we should shut down the Internet until we all get, say, 100G fibre to our homes. We should stop firing off rockets until we figure out how to build a space elevator. We should stop building automobiles and wait for George Jetson's flying car (all the places we need to visit aren't going anywhere). Do you not understand what spurs technological advance?

I'm curious; what "limited resource" are we not spending efficiently? How would you reallocate resources?
antialias_physorg
4.3 / 5 (6) May 17, 2013
Because 50 years from now, or even 10, this same mission will cost a pittance compared to the present cost

Which is a pointless argument because if you go by that then you never do anything. And no: without actually trying it out it doesn't cost a pittance. Cost savings only ever kick in if you have a TRIED and true technology you can optimize. And unless you TRY you don't know. Science isn't engineering.
(Also there are a lot of fixed costs for putting sattelites in such an orbit - none of which will come down in the foreseeable future)

And I'm sure that you'de be screaming your head off just as much if people DID just sit in their garages and send money on perfecting stuff without ever putting it to use (or trying if it even works).

NASA allocated the funds based on what was affordable and doable at the time.
Blakut
5 / 5 (1) May 17, 2013
Even if they get astronauts to it, if it was not built with servicing in mind, there may be no easy way to repair it in orbit.
CreepyD
3.7 / 5 (3) May 17, 2013
The cost of these missions IS a pittance already.
I think this mission cost $0.5 billion if I recall. Compared to what's spent on other pointless things, that's nothing. Also compared to the data it's given us, it's well worth it.
This mission has enabled us to learn more than any other space mission ever imo, and I'm sure follow up missions will come.
antialias_physorg
4.4 / 5 (7) May 17, 2013
Even if they get astronauts to it

From the graphic at wikipedia about the orbit(position of Kepler
https://en.wikipe...rbit.png
I made a quick guesstimate as to the current distance and came up with roughly 24 million kilometers (which is about half the distance between Earth and Venus orbits)

Needless to say we haven't gotten humans that far out. Ever. (Much less on something as complicated as a repair mission.)

For the cost of a repair mission you could send a dozen new Kepler telescopes up there.
philw1776
2.7 / 5 (6) May 17, 2013
The good news is that there remains a backlog of data to be processed and analyzed with discoveries forthwith. Hopefully TESS late this decade will continue the discoveries focused on nearer stars. The biggest bummer is that the Terrestrial Planet Finder mission remains a power point proposal, unfunded.

Kudos to the excellent Kepler team. True pioneers.
Maggnus
5 / 5 (3) May 17, 2013
The biggest bummer is that the Terrestrial Planet Finder mission remains a power point proposal, unfunded.


The James Webb TPF mission is well on it's way to completion. See here: http://www.nasa.g...ete.html

There was an issue with funding during budget debates in the US, but that was resolved, as far as I know. Did I miss something?
Mayday
5 / 5 (1) May 19, 2013
An important point that should be remade is that money spent on space research and exploration is not "wasted." The money is always spent here, on Earth. It creates real jobs, meaningful careers, and an enormous general advancement of knowledge and technology. The money in the NASA budget goes back into the economy. And the technology filters back into our lives (you're probably looking at some right now). If you live in a community where NASA employees and its contractors live, you benefit as well. I wish they taught some real economics in our schools, don't you?