With Fuel Exhausted, NASA Retires Kepler Telescope (space.com) 124
ewhac writes: NASA today announced that it is retiring the Kepler telescope after nearly ten years of service -- double its initial mission life. In that time, Kepler discovered over 2,600 exoplanets, most of which are between the size of Earth and Neptune, sparking an entirely new field of astronomical research, and revealing for the first time just how common exo-planetary systems are. With its fuel supply exhausted, Kepler is no longer able to maneuver or reorient itself to make observations. NASA has elected to decommission the spacecraft and leave it in its current, safe orbit away from Earth.
Fill 'er up? (Score:2)
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There might not even be an accessible fuel valve.
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Plumbers (pro and amateur) handle this all the time. It's called a hot tap.
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Planned obsolescence (Score:2)
Claims of exceeding the initial plans look much better than "oops, we didn't provide for refueling".
Managing expectations is the key — remember, for another example, the Mars vehicles? How every report about their adventures included a reminder, that they've exceeded expectations and therefore we ought to welcome whatever results we got from them, instead of asking, why this or that subsystem stopped functioning...
Excellent PR-job, NASA. The private sector, often blamed
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How would you plan to refuel something that is ~150 million kilometers, roughly 100 million miles, away from your planet?
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The distance is irrelevant — if a maintenance craft can get to it at all, it can refuel. International Space Station is 254 miles above Earth, but is routinely resupplied (and refueled) despite this much higher altitude.
If we can send a car into space [slashdot.org] just for the heck of it, we can reach any object in the Earth orbit...
The process of refueling in space is, likely, even easier than
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254 miles is NOT higher than 100,000,000 miles.
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Ooops, you are right, I misread the numbers.
But it is still reachable — if we were able to send Kepler there with the 2008 technology, we could've sent a refueling craft with 2018 (and even 2014) technology... If, that is, we allowed for it back then.
But, hey, maybe not. Maybe, it really was — and still remains — an impractical thing to do and the obsolescence planned by NASA in 2008 is reasonable and proper. Which, in turn, ought to remove th
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Could we?
Is 8 years (2008->2014) enough time to develop the technology to intercept Kepler and refuel it?
It seems unlikely that one could get there so much faster, use the fuel required to then match speed, and then transfer the fuel in a way that doesn't create its own problems with trajectory.
I'm not a scientist, but what little I know leads me to believe the real life application is even more difficult.
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They didn't need to know about it. They just had to provide for the the externally-reachable fuel valve or some such.
Faster than what? We know the exact position of the telescope at any time. The intercepting mission could aim for where the craft will be years after it is launched — and get there, slowly...
Absence of the vagaries of air-currents
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But the refuel mission would need to match it's location in 2 years, and then slow down to match its speed.
One may as well ask why we didn't just launch a second refueling vessel at the same time, or maybe just make Kepler bigger.
Both of these are easier solutions.
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We can't get autonomous cars to 100% never crash into big red firetrucks yet, and you want us to do a refuel mission that due to the distance HAS to be fully autonomous and have millimeter precision.
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It doesn't need that much precision, really.
Get on a similar orbit. Slow down until it's 100 miles away. Match speed.
Tap the gas to adjust gradually. When you're getting close, initiate some capture or docking maneuver. You can do either extremely slowly. For a capture, you can extend the arm and wait for mission control to confirm. Then you can open the arm and wait for confirmation. Then you can lower the arm and wait for confirmation. Then you can close the arm and wait for confirmation. Then you
Re: Planned obsolescence (Score:2)
To my knowledge, a car doesn't have to functions in low orbit. Also to my knowledge where Kepler is currently is not low orbit.
In what way is fueling a spacecraft easier than fueling a plane? A spacecraft is likely moving 100x - 1000x faster. Also fueling systems for planes rely on gravity which is a problem in outer space. The last time I checked it is relatively easy to launch a plane. Launching a space craft takes lots more time and effort and cost to coordinate.
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Speed is not necessarily the issue here, but as you said chucking a large object on a random heliocentric orbit is not the same as refueling in space.
Space maneuvers and orbital mechanics are another beast completely, there is no comparison to any earth-based phenomenon - it's not easier or harder than refueling a plane, it's simply something completely different, there is nothing comparable. It's like trying to compare recipes to algebra - there are easy and hard recipes, and easy and hard formulas, but yo
Re: Planned obsolescence (Score:2)
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Because Kepler is 137 million km from earth.
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Kepler orbits the sun, not the earth, in an earth trailing orbit. So, yes, the cost of refueling it would be a bit high. One might say the cost would be astronomical.
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Yes, by several orders of magnitude.
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Why would it be heavier?
It only needs to carry the fuel and a refueling mechanism, a replacement needs to carry the fuel and a telescope. I would imagine a refueling mechanism could be quite a bit smaller/lighter..
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If it's not designed for refueling then there won't be a filler cap. Or anywhere to grab onto.
And it's probably impossible to do without destabilizing the orbit.
.
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Then they designed it poorly. And if you can refill it, it can readjust its orbit.
I'd wager the cost of a refueling mission would be well worth it. The value of completing such an exercise would be far greater than the value the telescope itself provides.
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You need the fuel to get there too.
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Even if you could build some sort of fuel tanker craft to go a fuel up the telescope, that was cheaper than a new scope and lest costly to launch you still have to consider the risks..
You are talking about doing something by remote control our automation over vast distances; with limited ability to make any corrective actions once the match is struck so to speak. It requires an extremely high degree of precision as well. The slightest anomaly or error and you miss by mile trying to do something where mill
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Re: Fill 'er up? (Score:2)
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You want to re-route to the end of the universe? It could work, but it seems infinitely improbable.
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Being that the Kepler is further away then our Moon is. And the moon is still currently the longest space flight we have manually manned. I would think so.
Even if we were to have a robotic fuel craft. Creating such a craft and have it make a such detail connection to refuel it. Would still be more expensive then launching a new telescope.
We can also launch a new one with better technology that can dig even deeper then what the Kepler could.
Part of the problem with the American Space Shuttle program was th
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Re: Fill 'er up? (Score:2)
And considering where Kepler is , the logistics are closer to a mars mission than a moon Mission. People seem to be under the impression it's ISS distance. Frankly it'd be cheaper to send a more up to date replacement and use the savings to fund a moon mission
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Why not refuel? Would the cost of a refueling mission be greater than a whole new telescope?
That is basically the issue. The cost of designing, building, and launching a refueling mission is comparable to the cost of launching a replacement probe if you planned ahead by making more than one and the probe has a limited and unknown remaining operating life.
Considering the cost of Shuttle launches, I suspect the same applied to the Hubble but it made a great justification for the Shuttle.
Re:if only (Score:5, Informative)
For Hubble, maybe. But Kepler is currently 187 million kilometers behind Earth on a heliocentric orbit and drifting back at 31km/s. Nothing we had, have or will have for a long time can reach there to do a refueling job. It was designed as a sacrificial instrument from the start.
Re: if only (Score:2)
A DSV-1 with suitable payload could get there.
Re: if only (Score:5, Insightful)
A DSV-1 with suitable payload could get there.
At great cost with money that should go for the next generation of spacecraft.
Look, Kepler served its purpose. It confirmed over a thousand exo-planets, and thousands more unconfirmed. It is not particularly useful to find a few hundred or even a thousand more. Kepler has been in space for 10 years, and was built with tech even older than that. It is time to move on.
We need a NEW spacecraft that can detect smaller planets, planets further from their star, and even exo-moons. We need to be able to look for spectroscopic signs of O2 in star-crossing exo-planets, which may mean life. Spending $500M on a refueling mission will accomplish none of this.
Re: if only (Score:5, Informative)
A decade of improvements (Score:2)
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I'm not disagreeing with that.
I've pointed out elsewhere how to build a telescope capable of spectrometry on Earth-sized planets hundreds of light-years away. Getting a lot of flak for pointing it out, I should add.
So that's the choice. An obsolete telescope we technically can refuel but probably shouldn't, and a space-based interferometer capable of everything you asked but is utterly rejected and despised by many on Slashdot.
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utterly rejected and despised by many on Slashdot.
NASAs research priorities and budgets are not set by the Slashdot consensus. So what does it matter what people here think?
Re: if only (Score:2)
Congress wouldn't pay for manned space flight.
Re: if only (Score:2)
NASA's estimate for such a journey is 16-20 years.
Such a probe could return in a viable length of time. Easier than transmitting data 4.1 light years and you'd get better bandwidth.
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Nobody has any theory for how to make an interstellar probe return. Any solar sail that can manage to keep accelerating long enough to get up to an appreciable fraction of the speed of light will have no prayer at stopping, because solar sails only work within star systems and it'll be going so fast it'll pass through the star system in far, far less time than it spent accelerating in ours. You need an equal amount of time in the same energy conditions to decelerate as you had to accelerate.
Re: if only (Score:2)
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Why? You have two sets of solar sails, one facing one way, one facing the other.
You don't need the ship facing the other way. The ship isn't doing anything useful, it's space not water.
You open up the first set on leaving, jettison when it ceases to be useful, then open the other set at the equivalent point in the other system.
0 + X - X = 0
Repeat the process for the return journey.
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The fastest probe we have ever sent goes 0.023% the speed of light.
The fastest we have even sent an object is 0.000135% the speed of light.
So which is it?
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NASA calculates a solar sail could accelerate a probe to 0.25 C.
That fast enough for you?
If you want to tell them they're hopeless at engineering, go right ahead. That's between you and them, though.
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Interesting, but a return means it has to slow down again in our solar system which is a couple of stars short of the requirements. And the 4.6% of C limit means we're looking at a nearly 200 year round trip, which is a lot harder to secure funding for than a 50 year trip some people will actually live to see the results of.
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Solar tacking, duh.
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You have two solar sails.
Remember, the equations most balance, so you have a solar sail for going out, which you discard when acceleration approaches zero (as galactic winds will essentially act as a brake) and you open up a second solar sail facing the other way when you reach the equivalent point in the other solar system.
You now degenerate to zero, since the total momentum exerted in each direction must now be equal and you started at zero.
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That doesn't make any sense. All other things equal, if a star can accelerate a probe with a solar sail to a certain speed away from the star, the same star should be able to deaccelerate the same probe back to the speed it started at when it approaches the star.
Of course, a few things that might make it unequal is that we could bounce the probe around our solar system and sling it around some planets to give it a boost (and the probe would get a boost simply because we would launch it from Earth which its
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Any solar sail that can manage to keep accelerating long enough to get up to an appreciable fraction of the speed of light will have no prayer at stopping, because solar sails only work within star systems and it'll be going so fast it'll pass through the star system in far, far less time than it spent accelerating in ours. You need an equal amount of time in the same energy conditions to decelerate as you had to accelerate.
So either dive into the sun at the target system or do what Robert Forward suggested:
https://arc.aiaa.org/doi/10.25... [aiaa.org]
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The fastest we have even sent an object is 0.000135% the speed of light.
The fastest probe we have ever sent goes 0.023% the speed of light.
So which is it?
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I'm going by a 1989 NASA calculation for a solar sail.
They reckoned that you need 1 square km of sail per 10g of probe, but that you could reach a quarter light speed by the time you exited the solar system.
Since the fall off of energy follows the inverse square law, and the mass will increase due to dust and other debris accumulating on the sail as a function of velocity, it seems reasonable to assume that if their 0.25C is correct, you'd reach more than that half way (since you'd have much less than half
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Cost of maintaining shuttle programme: fixed costs plus cost per shuttle. Kicker: the fixed part is very, very non-trivial!!! An operational shuttle is not something you just keep around.
Secondly, it is well known that the shuttle design was a compromise of so many "things" it was supposed to do, that it was never anywhere near the original ambition of having something you could land and then just fly again, and is seen by many as a bit of a failure. Just search for "space shuttle bad design" and you'll get
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The old shuttles, whether USA or Rusian, would not be able to reach the Kepler. It is verrrrrry far away from earth - millions of kilometers.
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and is seen by many as a bit of a failure
NASA is either terrible at estimating their equipment lifetime or good at keeping positive press by publishing an expected lifetime much shorter than the real lifetime.
The glass is twice as big as it needs to be.
Re: if only (Score:2)
Or that NASA is good at over-engineering things so that they complete the mission objectives. If Kepler didn't last as long enough to complete the initial mission time, would the US government and the people keep funding them?
If we take the example of the Mars rovers Spirit and Opportunity, NASA (and no one else) knew what the climate of Mars would do until they sent the rovers. The main concern with the rovers could be engulfed in dust storms for weeks as soon as they arrived. So they overbuilt the battery
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Over-engineering is when you pay $350Bn but you needed $200Bn to finish the mission. That's waste.
Efficiency is when you need to pay $200Bn to finish the mission and you pay $210Bn to get twice as much out of it.
NASA has a record of claiming that things like the Mars Rover are performing amazingly, and that they don't understand how it's been able to keep going so long. They should have a risk profile that shows e.g. 50% likelihood of meeting mission objectives at $200Bn spend, 95% at $250Bn spend, 98
Re: if only (Score:3)
The whole problem with your premise is that it requires omnipotence and premonition. In hindsight you can claim something wasn't efficient when it exceeded the original goals but back when these things were launched no one had any knowledge of the future in how long things would last.
NASA never claimed one iota of what say they claimed. Instead NASA was given clear mission parameters and a budget which they had to meet. In the specific case of the rovers they didn't know the severity of dust storms or how b
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The whole problem with your premise is that it requires omnipotence and premonition.
Dude I have certification in a field centered around this, and I don't have certification in the specific KA for people who took extended study in estimating. Yes, there's actually certification specifically for estimating, and for risk management, and a number of things.
In the specific case of the rovers they didn't know the severity of dust storms or how badly it would degrade battery charging.
The Rover should have had a more-detailed analysis. NASA was actually pretty accurate with their predictions of its lifetime; they had anticipated dust buildup on the solar panels, and the dust storms were actually cleaning the solar pa
Re: if only (Score:2)
Dude, so you knew 16 years ago how dust storms would affect both rovers over the course of the next 16 years? Why the hell didn't you tell NASA so they didn't have to design to the worst case scenario?
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They didn't just design for the worst-case scenario. They overbuilt.
What's your excuse for NASA not being able to figure out how much fuel long-term space probes consume?
Re: if only (Score:2)
So your answer really is you didn't have the slightest clue about the future. So what I said before: NASA doesn't have omnipotence. Funny how that applies to everyone.
As for Kepler fuel, you do understand that most things are designed with a 2X safety factor right? Kepler's original mission was 3.5 years. 2X would be 7 years; however, in 2013 (4 years into the mission) failure of a 2nd reaction wheel meant that mobility of the telescope was limited. Thus they didn't use as much fuel as they would have used
Re: if only (Score:2)
Mission parameters of Pathfinder: 1 month
Actual mission duration of Pathfinder: 3 months
Pathfinder didn't give NASA an entire year of data much less a decades worth to determine charge rates, cleaning etc. Remember extrapolation (which NASA had to guess) != interpolation.
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You don't seem to understand anything about estimating. Pathfinder gave NASA ground data to correlate with telescope data, enabling them to model the Martian atmosphere--that was the point. The biggest miss on Opportunity was predicting a continuous coating of dust on the solar panels, which didn't happen at all.
A month is enough to get a read on insolation at ground versus in space versus weather, by the way, so NASA has a pretty good estimate of year-long insolation data, and can work out charging rat
Re: if only (Score:2)
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The weather patterns weren't unusual and unpredicted; the probe's performance given those patterns was.
Re: if only (Score:2)
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The shuttle couldn't come close to reaching this, it would take an Apollo-level manned mission to even get there.
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If we only had a craft able to fly up there and refuel and fix/upgrade it... oh wait we DID! NASA really should have kept 1 space shuttle for just this kind of mission. Sigh. Oh well.
It's almost as if you don't know where this thing is orbiting.
Clue: Shuttles aren't designed for deep space missions.
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Kepler is way out of the shuttles range.
Besides the shuttle ability to do such things was over exaggerated, and a normal rocket design could probably do such safer and cheaper then the shuttle.
Salud! (Score:5, Informative)
Farewell and thank you for a job well done. It's important to remember to count all the victories and remind ourselves at how good it can be. Who would have thought that astronomy would be a hot field? But with better eyes and better thoughts we can peer deeper into the inky blank and make better sense of what we're seeing. Human advancement is possible. The stars are ever closer. Thank you Kepler.
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Farewell and thank you for a job well done.
Did the last person to use it leave it pointed at the Earth or something? It's still going to be pointed at something. Have it take pictures of that.
Not much of a choice (Score:4, Insightful)
With "its fuel supply exhausted", NASA has "elected to [...] leave it in its current, safe orbit". If you have only one option, seems to me there is not much electing to be done ...
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It can also be taken to mean they won't fire anything at it to push it away from Earth because it's ALREADY pushed away from Earth.
Re: Not much of a choice (Score:2)
They could slowly spiral it into the sun, or they could use the fact that it has to reflect a lot of light to slowly push it into an outward spiral.
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No, they can't do either.
- spiral into the sun needs alot of delta-V Kepler doesn't have
- use light reflection to sail it requires an active system to keep the attitude stable, Kepler doesn't have that either.
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with only 2 reaction wheels, the spacecraft will drift around one axis, so there's a good chance the solar pressure will be converted into rotation rather than delta-V.
And oh yes, keeping Kepler running in this mode for another decade means another decade of operation cost for no benefit.
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Next! (Score:2)
Don't decommission it (Score:2)
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Radio Amateurs do it all the time - it's a particular subset of the hobby. There are some tiny cubesats orbiting around for this exact purpose. It takes a bit of work and equipment but is doable.