With Fuel Exhausted, NASA Retires Kepler Telescope (space.com)

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.

Comments

THERE WILL BE CONSEQUENCES FOR YOUR LIES KEN DOLL

[Anonymous Coward]

THERE WILL BE CONSEQUENCES FOR YOUR LIES NAZI FAGGOTS INCLUDING KEN DOLL

Filter error: Don't use so many caps. It's like YELLING.

Filter error: Don't use so many caps. It's like YELLING.

Fill 'er up?

[Squeeonline]

Why not refuel? Would the cost of a refueling mission be greater than a whole new telescope?

Re:Fill 'er up?

[Calydor]

There might not even be an accessible fuel valve.

Re:Fill 'er up?

[Anonymous Coward]

Because Kepler is 137 million km from earth.

Re:Fill 'er up?

[Anonymous Coward]

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.

Re:Fill 'er up?

[Brett Buck]

Yes, by several orders of magnitude.

Re:Fill 'er up?

[Anonymous Coward]

Indeed. The refueling vehicle would be much heavier than a new satellite - and therefore much more expensive to get into the same orbit - and then out of the way (or even back to earth again).

Re:Fill 'er up?

[csmithers]

Yea, unmanned vehicles are not normally designed to be refueled, especially when they are 94 million miles away. Manned vehicles, however, present a different problem. You really can't leave a person out in space without attempting a refuel, can you ?

Re: Fill 'er up?

[Type44Q]

Is that how it works??

Re:Fill 'er up?

[thesupraman]

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..

Re: Fill 'er up?

[Anonymous Coward]

Could you refuel the Apollo CSM in space? The LM? The Shuttle?

Re:Fill 'er up?

[Joce640k]

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.
.

Re:Fill 'er up?

[Anonymous Coward]

Plumbers (pro and amateur) handle this all the time. It's called a hot tap.

Re:Fill 'er up?

[Anonymous Coward]

Considering how much time and effort goes into a simple hubble repair, a Kepler missions seems far fetched. NASA would have been the first to sign up for any reasonable idea. Everybody has seen how well they treat their spacecraft and historic artifacts.

Re:Fill 'er up?

[Anonymous Coward]

Yea, unmanned vehicles are not normally designed to be refueled, especially when they are 94 million miles away. Manned vehicles, however, present a different problem. You really can't leave a person out in space without attempting a refuel, can you ?

If you're sending a manned vehicle in deep space and it is running out of fuel just tell the pilots to stop at Milliways. I've heard they have a great restaurant and they will fill up your gas tank as a bonus.

Re:Fill 'er up?

[RobinH]

Well, if they forgot to include a docking port, they can always to up there an attach to it with an Advanced Grabbing Unit and transfer fuel over that way, right?

Re:Fill 'er up?

[Anonymous Coward]

Well, you wouldn't need to attempt a refuel, but it might be somewhat unpopular of a decision and would probably end all involvement you currently have in society if you didn't.

Re:Fill 'er up?

[jellomizer]

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 the idea of a reusable space craft, because that is what we see in Science Fiction and our idea of a spacecraft. But we found out that for the most part reusable space crafts are not affordable and safe.
Sure we as the little people get side tracked that equipment that cost more then all the homes in swanky high end neighborhood, to be disposable after a few years. But that is the nature of space economics. It is expensive, and even more so to go back, or to do maintenance. It just doesn't have the economy of scale.

Re:Fill 'er up?

[jellomizer]

You need the fuel to get there too.

Re:Fill 'er up?

[DarkOx]

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 millimeters count.

Our Areo-space engineers have done a lot of amazing things - frankly things that many thought would never be possibly. They are super smart folks who deserve a great deal of respect. Still something like this would have a pretty good probability of failure. Much more so because it was not planned at the outset and has not been done before so they have no experience with it. You have to add the chance of failure times the cost of the effort at least. Really its worse than that because we are talking about a single event not a case of of we are going to do this 1000 times and odds are 1% of the time it won't work so we more or less can expect to have to scrap 10 units..

Re:Fill 'er up?

[gnick]

You want to re-route to the end of the universe? It could work, but it seems infinitely improbable.

Re: Fill 'er up?

[Anonymous Coward]

Yes, mainly because you have a man. But I wouldn't recommend it. Those fuels are corrosive.

Re:Fill 'er up?

[kaizendojo]

With what? We don't have any shuttles anymore and we're some time away from manned missions to space again.

Re:Fill 'er up?

[sexconker]

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.

Re:Fill 'er up?

[SuperDre]

Refuling might be an option, if they still had a shuttle operational. But at the moment there is no shuttle operational (at least not publicly) for doing support missions like these. And I guess a small drone won't be good enough for completing a task like this..

Re: Fill 'er up?

[sg_oneill]

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

Re:Fill 'er up?

[jpaine619]

Are you fucking serious? You want to launch an entire spacecraft, to fly all the way out to Keppler, the resuscitate 2008 technology?

Why the hell wouldn't you just launch a new spacecraft, Keppler 2, with 2018 technology?

Jesus H. Christ..... This is common sense....

Re:Fill 'er up?

[Agripa]

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.

if only

[TheRealQuestor]

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.

Re:if only

[bruce_the_loon]

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

[jd]

Congress wouldn't pay for manned space flight.

Re:if only

[Anonymous Coward]

Or what if we would have included an packed solar sail to jettison the probe towards the nearest planetary system detected by Kepler? Just for the fun of it, of course. And to test some equipment while we at it.

Re:if only

[CptJeanLuc]

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 many hits.

Thirdly, I'd say that if they had kept the shuttle programme going, it would have stifled some of the innovation we are currently seeing.

As much as I would like to have shuttle capabilities, it was always a dead end in terms of being a platform for going further into space exploration.

Re:if only

[Anonymous Coward]

Kepler is 137 million km from Earth. About a million times too far away for the space shuttle to get to,

Re:if only

[Anonymous Coward]

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.

Re: if only

[jd]

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.

Re: if only

[jd]

A DSV-1 with suitable payload could get there.

Re:if only

[Brett Buck]

The shuttle couldn't come close to reaching this, it would take an Apollo-level manned mission to even get there.

Re: if only

[ShanghaiBill]

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

[Anonymous Coward]

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.

Dude the shuttle couldn't even get to 5000 km above the earth. Kepler is more than 100 000 000 km away. There is nothing we had, have or will have in the near future that can go that far away fill her gas tank and come back.

Re: if only

[Gavagai80]

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

[Type44Q]

Yeah, you'd have to include the ability to do a 180 halfway along your journey (assuming stars with equal output); definitely a deal breaker.

Re:if only

[Joce640k]

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.

Re: if only

[Anonymous Coward]

I like how you put that last part in bold.

Re: if only

[Jjeff1]

We have a replacement, it's called TESS https://tess.mit.edu/ It's not quite the same as Kepler, but has a similar mission. Good news is TESS's imaging sensors cover a LOT more area than Kepler.

Re: if only

[110010001000]

What planetary system could be reached within 16-20 years? The closest one is over 4 light years away. The fastest we have even sent an object is 0.000135% the speed of light.

Re:if only

[Anonymous Coward]

Erm, if nothing we had can get there, how did Kepler get there in the first place? Surely we must have had something to get it there in the first place.

Wouldn't a Falcon Heavy be able to send something to that orbit, as it has proved it can send a payload to Mars?

Re: if only

[RobinH]

It seems like there are some theories about how to slow down, at least if you're aiming for the Alpha Centauri system (which is a 3 star system).

Re:if only

[Anonymous Coward]

But Kepler is currently 187 million kilometers behind Earth on a heliocentric orbit and drifting back at 31km/s

I don't know the accuracy of that statement made by brucetheloon, but if correct, that's how. We put it into an orbit around the sun, and then we slowed it down a little, and over 10 years it's been drifting back behind us. If in 10 years it has managed 187m km, and the circumference of earths orbit is 940m km, we should be able to reach it in about another 40 years.

Re:if only

[jellomizer]

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.

Re: if only

[110010001000]

Alpha Centauri is 4 light years away. The fastest probe we have ever sent goes 0.023% the speed of light. That means it would take 17,000 years to get there. So unless there is some magical technology that can make probes faster, we don't need to worry about slowing down.

Re: if only

[Anonymous Coward]

It's called Daelecious (or something like that--my spelling is rotten) yielding 7% of c.

Re:if only

[bluefoxlucid]

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

[RobinH]

I think you're missing a big part of this discussion. :) It's about using a lightsail to accelerate a tiny probe up to a significant fraction of the speed of light using Earth based lasers. See the Breakthrough Starshot initiative. The discussion was about the difficulty of slowing down on the other end.

Re: if only

[UnknowingFool]

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 system to guarantee that the 4 month mission could be completed under the worst conditions.

Another factor is that Kepler and the rovers where never designed to be serviced so everything has to last as long as possible with no hope of service.

Re: if only

[bluefoxlucid]

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% at $252Bn spend; and also, a graph of likely mission opportunities (e.g. extended operating lifetime) at each spend level.

In other words: it's perfectly okay to say you built this to have a 98% chance of completing the mission and that there's a 50% chance of going an extra 2 years and a 20% chance of going an extra 5 years. It's deceptive to say you built this with an expected lifetime of 5 years and holy shit it's still going strong at 15 years! An expected lifetime of 5 years could be that you had a 6-month variation, and could be 50% likely to make it to 5 years, 90% likely to make it 4.5 years, and 10% likely to make it to 5.5 years. It could also mean that you had a 50% chance of failure by 5 years and a 10% chance of failure by 6 months, so you built it to have a 5% chance of failure by 5 years--and it has about 50% likelihood to make it 8 years and a 10% likelihood to make it 12 years.

That all sounds fancy, but it's standard. More than that, it misses the elephant in the room.

NASA didn't build Kepler or the Rover to last a few years before breaking down from component wear.

NASA built them to outlast their mission, and provided fuel expected to exhaust in the mission time.

NASA claimed this truck got 12mpg, fueled it up with a 35gal fuel tank so it could go 420 miles on a tank, and got 1,050 miles out of the tank because it actually goes 30mpg. WTF?

It turns out the tank only needed to be 14gal.

Re: if only

[jd]

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.

Re: if only

[sexconker]

Solar tacking, duh.

Re: if only

[sexconker]

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?

Re: if only

[sexconker]

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?

Re: if only

[jd]

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.

Re: if only

[jd]

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.

Re: if only

[jd]

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.

Re: if only

[jd]

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 the dust and much more than half the energy).

It takes about 17 hours for a signal to travel from the heliopause to Earth. If that's the edge NASA was using, it would take the aforementioned probe 5.7 days to reach it, which can't be right - the sails can't get enough energy in that time.

They might have been using the Oort cloud, which NASA's website describes as an edge of the solar system. In that case, you're looking at about a light year. That means under 8 years to get there, although most of that distance will be over 1/8 C.

So you've 2 light years to go at 0.25C (8 years travel) the 1 ly at either side. Let's say that's averaging 1/3 C. So that's 6 years on either side, bringing us up to 22 years. We're probably averaging more than that, since it's not linear acceleration. That's how you get down to below 20.

Re: if only

[Gavagai80]

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.

Re: if only

[UnknowingFool]

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 badly it would degrade battery charging. The worst case scenario had to be used to design the system.

Opportunity has possibly suffered the worst case scenario that NASA planned more than 16 years ago: an intense dust storm has possibly drained the batteries to the point where the rover is likely dead for good. It just took 16 years for it to happen.

Re:if only

[Anonymous Coward]

There is a difference between putting a sedan-sized object in orbit around the sun, and hitting an existing sedan-sized object currently in orbit around the sun.

Or for a baseball analogy (I know, I know, tradition is car analogies), it is easy for a batter to hit a ball 500 feet. It is much harder for a batter to hit a ball 500 feet and have it land in the exact same spot as the first.

Re: if only

[ShanghaiBill]

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

[bluefoxlucid]

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 panels, which caused the discrepancy.

Space vessels are a different matter: NASA has plenty of experience getting them into space and operating them in space. They know the power drain and the conditions of operation. It'd be nice if there were some fuel left over after launch, except the launch stages drop off the probe and so that extra fuel is lost. This leaves NASA with a pretty good idea of exactly how much fuel they have once they get into space--and, besides, once they're in space they know how much fuel they have and can re-estimate from there.

That means NASA should be able to predict space vessel lifetimes pretty well. They're built to exhaust their fuel source, and NASA knows how long fuel lasts. NASA knows the operating conditions and the fuel demands. At some point, NASA should be able to determine the probe's lifetime, rather than calling it at 5 years and having half the fuel left at 10.

The same is, again, not true of things in orbit which we repair. We end up extending their lifetimes by intervention. This is also why nobody can predict how long a car will last.

Re: if only

[UnknowingFool]

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?

Re: if only

[UnknowingFool]

In what world did NASA have enough data for detailed analysis? The number of previous battery operated, solar powered rovers before Spirit and Opportunity: 1 (Mars Pathfinder)
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.

Re: if only

[bluefoxlucid]

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

[bluefoxlucid]

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 rates from that to relatively-high accuracy because they have a lot of data about how atmosphere interacts with insolation. They also knew a lot more than you do about batteries, and estimated a shorter battery life and higher wear.

As to extrapolation versus interpolation, most estimating isn't exactly that. A lot of estimating is "A is like B, and X is like Y except smaller/bigger and made with B. We've been using a new technique to do C, which is completely-unlike B, but should apply to parts of the process of doing B, so B should be improved in budget and time by these factors. Doing X should thus come out in this manner. Here's the time, budget, and resources necessary." We've never done anything like this, but we know about how much it should cost and how long it should take--and what the variation is in our estimates (i.e. risk).

Re: if only

[UnknowingFool]

You don't seem to understand that one month of data isn't enough to predict 16 years worth of data. Can you use one month of data here on Earth to forecast 16 years? Hell no. Yet you think you can magically predict weather on another planet where we didn't have detailed data.

Re: if only

[UnknowingFool]

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 if the wheels kept functioning.

In other words, Kepler was fully functional for only 4 years or so. NASA has been able to work around the failures for the last 5 years by refining what it could do. Which means you were basically dead wrong about Kepler.

Re: if only

[toddestan]

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 itself is moving). We could reverse that in the target solar system but pulling that off might require knowing more about the characteristics of the target solar system than the data we'd have at launch.

Another factor would be how luminous the target star is - a star less bright than the Sun obviously won't be as effective at slowing the probe down than our Sun would be at accelerating it. But that could be used to our advantage in the case sending probes to stars that are more luminous than the sun.

Re: if only

[Agripa]

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...

Re: if only

[bluefoxlucid]

The weather patterns weren't unusual and unpredicted; the probe's performance given those patterns was.

Re: if only

[UnknowingFool]

Extrapolation is not interpolation. Someone with the credentials you claim should know this. One month of Mars data doesn't begin to cover all the seasons of Mars. And all 4 Mars seasons take about 1.8 Earth years. I can't see how anyone can claim one month is enough data.

Salud!

[HeckRuler]

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.

Re:Salud!

[sheramil]

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

[CptJeanLuc]

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 ...

Re:Not much of a choice

[Calydor]

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

[jd]

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.

Re: Not much of a choice

[hackertourist]

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.

Re:Not much of a choice

[Anonymous Coward]

It's not like they weren't watching the fuel gauge. They've known it was low on fuel for years. They elected to use the last of the fuel for a few more days of observations rather than modifying the orbit.

Re: Not much of a choice

[SqueakyMouse]

Pushing it into a spiral means pushing it continuously. If you stop pushing it, then all you've done is changed its orbit. To make it spiral into the sun, it needs to be decelerated until its orbital speed hits zero. It's travelling at 30km/s and weighs a tonne, so it's not an easy feat to pull off.

Re:Not much of a choice

[Anonymous Coward]

So I guess that self-destruct mechanism was a bit of a waste then.

Re: Not much of a choice

[Anonymous Coward]

keppler doesn't have reaction wheels? Funny, I think it's got 2/4 sets working adequately. That's clearly enough to point the shiny side at the sun on half the orbit and the panels at the sun on the other half to pick up some energy from solar radiation. They've got "a long time" to pick up delta-V, probably another decade

Re: Not much of a choice

[hackertourist]

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.

Re:Not much of a choice

[Solandri]

Kepler is in a slight earth-trailing orbit. 371 days to orbit the sun once, instead of 365 like the Earth. So the Earth should catch up to it again in some 60 years, but because Kepler's orbit is slightly larger it's unlikely to intersect the Earth as the two pass each other again. The orbit was selected because it required less fuel to attain and maintain than the L2 Lagrangian point/a?, meaning more fuel could be used for observations.

BRETT BUTTFUCK HERE TO EXPLAIN SPACE TO US

[Anonymous Coward]

THANKS BRETT BUTTFUCK

Re:BRETT BUTTFUCK HERE TO EXPLAIN SPACE TO US

[Anonymous Coward]

Remember:
NO MEANS YES!
YES MEANS ANAL!

Supreme Court illegitimate filter encountered.

Not Retiring, KILLING

[Anonymous Coward]

It's like taking your wife's mother out to the forest and leaving her. Justifiable or not, it is a KILLING, homicide in the case of your mother-in-law. In Florida it is known as the stand-your-ground law.

Re:Not Retiring, KILLING

[Anonymous Coward]

Scientists bent on refueling Kepler are just as illogical as scientists insisting that something be done with Kepler.
Kepler is a legend of the space program. "Salute the sky and send it warm thoughts" is what they say at JPL. Well, I heard one guy say that once.

Re:Not Retiring, KILLING

[Anonymous Coward]

It's like taking your wife's mother out to the forest and leaving her. Justifiable or not, it is a KILLING, homicide in the case of your mother-in-law. In Florida it is known as the stand-your-ground law.

No one sane of mind should put "Florida" in any civilized discourse. Florida and Floridians are a certified basket case.
Lets not worry though, climate change will take care of them quickly enough.

unchosens wandering in desert 200+ years

[Anonymous Coward]

finally being airlifted/dropped off, at the grand matage casino... out back, near the employee tents..

THEN REFUEL ASAP

[sirv]

Refuel, bitches !!!

Next!

[Ihlosi]

Considering Kepler found 2600 exoplanets (maybe a few more will be found in exising data) by looking a small sliver of the sky, more advanced telescopes looking at different parts of the sky will certainly yield even more worthwhile discoveries.

Wall-E

[Anonymous Coward]

Wall-E will find it eventually, along with the rest of the space junk.

It's in an "Earth Trailing" orbit...

[Anonymous Coward]

I.e a period of a little more than a year but roughly the same as earth's. That's a reasonable place
to leave it. If it were in an Lagrange point it might be worth not junking that location up for
future missions, although I'm not sure enough of scale to know if that even matters.
How 'big' is the useful area around L2 anyhow?

Why fuel?

[Anonymous Coward]

Why does it need to use fuel at all, when it could use gyroscopes?

Archaeology in the making

[Anonymous Coward]

I love it.
It joins all the other drifters and landers spread around the solar system.
Hopefully whoever finds it puts it in a museum or collection, and not a junk pile.

Don't decommission it

[chiefcrash]

Instead of decommissioning it, why not open it up to amateurs? They won't mind where it's pointed for the chance to play with it...

Re:Don't decommission it

[LordWabbit2]

Agreed. Would love to even get the chance to ping a satellite.

Re:Don't decommission it

[hoofie]

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.

Re:Don't decommission it

[Anonymous Coward]

If the antenna isn't pointed at Earth, they'll never get to play with it.

Planned obsolescence

[mi]

double its initial mission life

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 for planned obsolescence of consumer devices, ought to take notice. If your iPhone still works after one year, that is a wonderful feat of technology — quit whining, rejoice, and pay us for a new telescope, er, phone.

Kepler discovered over 2,600 exoplanets

Yes, enforcing laws, defending borders, and searching for exoplanets — exactly the things government is supposed to be doing...

Re:Planned obsolescence

[Calydor]

How would you plan to refuel something that is ~150 million kilometers, roughly 100 million miles, away from your planet?

Re:Planned obsolescence

[mi]

How would you plan to refuel something that is ~150 million kilometers, roughly 100 million miles, away from your planet?

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 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 it is for airplanes. And American airplanes have been refueling in flight for decades. It is a solved problem. Indeed, NASA are already researching robotic refueling of satellites themselves. Back, when Kepler was designed, they could've provided for a possibility of a manned refueling mission...

Re:Planned obsolescence

[Calydor]

254 miles is NOT higher than 100,000,000 miles.

Re:Planned obsolescence

[mi]

254 miles is NOT higher than 100,000,000 miles.

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 the stigma from the very term "planned obsolescence" and we should stop blasting private companies for it too...

Re:Planned obsolescence

[AvitarX]

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.

Re:Planned obsolescence

[mi]

Is 8 years (2008->2014) enough time to develop the technology to intercept Kepler and refuel it?

They didn't need to know about it. They just had to provide for the the externally-reachable fuel valve or some such.

It seems unlikely that one could get there so much faster

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 — which aerial refueling is subjected to — makes space refueling much simpler...

Re:Planned obsolescence

[AvitarX]

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.

Re:Planned obsolescence

[Calydor]

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.

Re: Planned obsolescence

[UnknowingFool]

For both Kepler and the Mars rovers, both the budget and the mission parameters called for a finite amount of time. The fact that they lasted longer than the mission parameter is not "planned obsolesence". This is bonus results. This is also the situation where launching another vehicle or rover would cost so much more that it is cheaper and easier to keep using what is already been launched and re-purposing it.

Re: Planned obsolescence

[UnknowingFool]

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.

Re:Planned obsolescence

[sexconker]

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 can retract the arm and wait for confirmation. Then you can attempt refueling connection and wait for confirmation. Then you can open the valve on the receiver and wait for confirmation. Then you can open the valve on the giver and wait for confirmation. Then you can reverse the process.

At each step you can pause and wait. And each step gets you to a separate step where you've got more control. You don't need to hit a hole in one from Earth to Keppler. You drive out, use your wedge on the hazards, then pull out your putter once you're on the green.

Re: Planned obsolescence

[Karhgath]

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 you cannot compare them.

Kepler is more or less immobile (relative to an object trying to dock with it) Docking with something "immobile" in space is both extremely complex and quite "easy" to do now. It's one of the more difficult maneuvers you could do in space (probes landed on the moon before the first docking in space), but like anything, it's easier when you've done it hundreds of time, and have technology and algorithms on your side to account for comm delays and such, calculate precise trajectories, etc. Still, I do not believe we attempted automated docking outside of Earth's orbit ever - I'm sure we could attempt it, and the theory is pretty close, just that we have no practical experience and it's expensive to attempt.

You cannot use Kepler to slow down the refueling crash like a planet/celestial body, so you need to rendezvous with it. A rendezvous with the ISS is "easy" as it can be intercepted at specific interval from Baikonur, so you need minimal fuel and maneuvers to change plane and such. Now, Kepler is on a heliocentric orbit, so to be able to launch and "eject" the refueling craft on the same plane as Kepler takes fuel. Depending on timing and parameters compared to Kepler's launch, it could take either more fuel, or we'd have to wait for a good window (not sure on the timing here). After that, you get an object on the same plane but a very different orbit than Kepler/Earth that must match Kepler's orbit, which an take a lot of fuel and a lot of time.

But wait!! Kepler orbit is not exactly the same orbit as earth, and actually is slightly "larger", so Kepler is "slower" than earth. By now (10 years) it's incredibly far behind Earth. To slow down an object to reach it, you would need tons of fuel (accelerate, wait, then decelerate), or wait years and years to reach it with minimal fuel. If we double the "speed" of the refueling craft vs Kepler, we need to slow down equally after and it would still take 10 years to reach Kepler, for a lot more fuel than Kepler used.

Then, you get there... and you are correct on your second point - refueling in space is hard (no gravity). Refueling the ISS with people assisting and having very large equipment available is much much easier than an automated refueling being done remotely with small crafts, much longer communication delays and such. Then Kepler was not made to be refueled...

So yeah, not an easy feat at all. Oh, and you want fuel remaining to "ditch" the refueling craft, you don't want it interfering or risking collision.

Re: Planned obsolescence

[Anonymous Coward]

Can you consult your nearest math nerd to see if all your âeasyâ(TM) step by step is actually doable.

Re:Planned obsolescence

[Anonymous Coward]

The real question is what is the cost of a re-fuelling mission compared to a completely new telescope. Usually, the cost of these things is in design and in getting them up there - so my guess is that if we just wanted more Kepler, it would be cheaper to build another Kepler telescope and launch that than to design and run a different mission to refuel.

Open up it's current data feeds to amateurs

[Anonymous Coward]

I think it would be interesting to just leave it's instruments turned on and create a feed where amateurs could pull down the data and look at it.

A decade of improvements

[Fencepost]

It's not like there have been any significant improvements in digital imaging, low-power processing, attitude and position sensors and miniaturization in the decade since Kepler and the iPhone 3G were built and launched.