Author Topic: Long life probes for exploration of the Solar sytem  (Read 1877 times)

Offline jee_c2

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I just read about the Dawn probe, which was launched in 2007, more than ten years ago.
I thought, that may be it is worth to think about a different approach on the exploration of the Solar system through autonomous spacecrafts. I thought of probes, which could operate for almost unlimited time, exploring, and making missions after missions.

What are the limits for a space probe to keep operating?
If we want real long operation time, probably the best energy source is the solar panels (even though, this restricts the operation zone). Best examples for this are the Mars rovers.
I've read an article about better (longer lifespan) solar panels for space applications: https://www.inverse.com/article/45212-ultra-thin-solar-panels-power-esa-satellites.

Propulsion is the next question: the winner should be some very high specific impulse engine (Ion thrusters probably). The biggest problem is the fuel for the engine, which will be out sooner or later. Atmospheric scooping - could it be a solution? Or in space tank station(s)? Or some method to gather proper reaction mass - from asteroids, or from the rings of one of a gas giant?

And the instruments, the electronics, sensors, and the structural elements - I think, those can function for long enough properly.

So, I imagined a fleet of these spacecrafts, sending around in the Solar system on different missions, sending back their collected data for process here on Earth. The probes could be built in series, making tens, hundreds of those. Could contain AI as part of their control. Could communicate with each other (creating in space network), making it easier to send back information.

While having longer lifespan, the probes should be built for relatively easy in space upgrade (changing sensors, putting better processors, more storage, perhaps even better solar panels, ...

So this could really boost the exploration of space around us. The point is: a different approach (like, when we talk about ELV-s and reusable ones).

What do you think about it? When could this kind of probes be built, and when are we going to do that (I think it is rather a "when?" than an "will we ever?")? What are the options, and problems, questions for the different subsystems? How should be the operating of these look like? What could be the objectives beside exploration (i.e. space mining, communication, ...)?

Offline high road

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Re: Long life probes for exploration of the Solar sytem
« Reply #1 on: 06/03/2018 11:12 AM »

Well, considering the infrastructure required to produce the fuel on site, swap out components and the vast amount of time needed for the spacecraft to travel between locations, I highly doubt this would be a better approach than sending spacecraft with a limited lifetime to a limited set of destinations.

Drop refueling, unlimited lifetime and changing out equipment, and we're already there. Dawn is orbiting its second destination. New Horizons is moving towards its second target. Kepler and Pioneer are still gathering data that was not part of their original mission.

The biggest problem is equipment eventually breaking down, like reaction wheels (Kepler, Dawn) and fuel valves (Juno), followed by fuel eventually running out.

Offline jee_c2

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Re: Long life probes for exploration of the Solar sytem
« Reply #2 on: 06/03/2018 07:26 PM »
Well, considering the infrastructure required to produce the fuel on site, swap out components and the vast amount of time needed for the spacecraft to travel between locations, I highly doubt this would be a better approach than sending spacecraft with a limited lifetime to a limited set of destinations.
Producing fuel on site? That is an option, but it depends on the propulsion engine, and what kind of fuel is proper for that engine.I.e. VASIMR: "The VASIMRŽ engines are capable of using almost any gas or substance with a high vapor pressure as a propellant." http://www.adastrarocket.com/aarc/faq1 So, may be, we do not have to make fuel, but rather it has to be collected. That could be via atmospheric scooping. Or it could be mining on a appropriate material, low delta V asteroid (/comet? if far enough from the Sun, may be).
Also, having a "stupid" (no scientific instruments), simple tank station satellite (probably on Sun orbit) could be the source of refueling.

Drop refueling, unlimited lifetime and changing out equipment, and we're already there. Dawn is orbiting its second destination. New Horizons is moving towards its second target. Kepler and Pioneer are still gathering data that was not part of their original mission.
Exactly, I totally agree. This was the original source of this idea. These probes demonstrate, that additional results can be achieved over the original plans, and also, that could remain functioning for a long  period in the space environment.
Based on these, the next logical step could be making multi mission probes, than going on, step by step and eventually reaching the described fleet of long fife, multipurpose exploration crafts.
I think, this will be a longer process, and will be done gradually. What I was interested in was, if this idea is known already, did somebody think about it, and at the current technological level, what are the biggest barriers.

The biggest problem is equipment eventually breaking down, like reaction wheels (Kepler, Dawn) and fuel valves (Juno), followed by fuel eventually running out.
Thanks. I see. Question is: can these built to be more robust? I mean, this is technological, engineering question. Of course currently, these probes were built for a certain mission(s), for a certain time. All the rest is bonus for us. That means, these parts should not be overdesigned, of course that is a cost factor as well.
SO, based on the failure of these constructs, is it possible to create ones, where these problems are solved. Or - by adding backup systems (this is also expensive in many fields!) - the whole craft could be made more robust. Robust enough to return for a maintenance service, when needed.
Thanks for pointing out the actual examples from real missions of these beak downs!

Offline Katana

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Re: Long life probes for exploration of the Solar sytem
« Reply #3 on: 06/06/2018 10:40 PM »
Metal fueled vacuum arc thruster burning iron asteroids may be possible.

https://iepc2017.org/sites/default/files/speaker-papers/paper_kuehn_iepc2017_0.pdf

Offline Kansan52

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Re: Long life probes for exploration of the Solar sytem
« Reply #4 on: 06/06/2018 10:59 PM »
For me, reduce the travel time on existing probes and more of them.

Offline jee_c2

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Re: Long life probes for exploration of the Solar sytem
« Reply #5 on: 06/08/2018 12:58 PM »
Metal fueled vacuum arc thruster burning iron asteroids may be possible.

https://iepc2017.org/sites/default/files/speaker-papers/paper_kuehn_iepc2017_0.pdf

I also thought about the possible application field for such (a fleet of) probes could be the Asteroid Belt, since here with proper preparation (i.e. the truster you mentioned) the refueling could be done from resources practically available in zero G - the probes could mine it's fuel from the selected asteroids.

Or, fuel could be produced from ice as well (https://www.space.com/9292-water-ice-common-asteroids-discovery-suggests.html). Mining that would be also easier.

Also, having these probes doing it's research would help gathering information about the asteroids faster for mining and utilizing operations in (and of) the Belt.

Offline Jim

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Re: Long life probes for exploration of the Solar sytem
« Reply #6 on: 06/08/2018 01:36 PM »

Also, having a "stupid" (no scientific instruments), simple tank station satellite (probably on Sun orbit) could be the source of refueling.

Drop refueling, unlimited lifetime and changing out equipment, and we're already there. Dawn is orbiting its second destination. New Horizons is moving towards its second target. Kepler and Pioneer are still gathering data that was not part of their original mission.
Exactly, I totally agree. This was the original source of this idea. These probes demonstrate, that additional results can be achieved over the original plans, and also, that could remain functioning for a long  period in the space environment.
Based on these, the next logical step could be making multi mission probes, than going on, step by step and eventually reaching the described fleet of long fife, multipurpose exploration crafts.
I think, this will be a longer process, and will be done gradually. What I was interested in was, if this idea is known already, did somebody think about it, and at the current technological level, what are the biggest barriers.


The whole concept is not viable

Tank statio is just not feasible and shows a lack of understanding orbital mechanics .    There isn't enough propellent or delta V to come back to tank station.


New Horizons is just flying out and found a target of opportunity that is in reach.  Voyager and Pioneer were planned to do their flybys so that they could continue the mission if they were successful going by Jupiter and Saturn

Dawn is just moving around the asteroid belt.  It can't come back near earth or go out to Jupiter.


The delta v to move around the solar system is just to great.  Anything that is past Jupiter, has to fly by Jupiter to get the energy to go further.   Same with going to Mercury or the Sun, but Venus is the flyby target. 

There is no coming back, they are all one way trips that continue

Offline jee_c2

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Re: Long life probes for exploration of the Solar sytem
« Reply #7 on: 06/11/2018 06:53 AM »
Sorry, my fault, I was not specific enough. Of course when I wrote about tank station, I meant it being in a proper orbit not"far" (deltaV) from the probes it is serving.

And this is only one of the options - not even the best. The other option is to make the probes capablee to gather their own fual. I mentioned two possibilities: atmospheric scooping and gathering material from the surface of an asteroid. (Or having an installed fuel processing module on an asteroid, from which it could be refilled.)

I would like to underline, this approach  is probably not for now, but some years (decade?) later. Tbc...

Offline IRobot

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Re: Long life probes for exploration of the Solar sytem
« Reply #8 on: 06/11/2018 07:29 AM »
If we want real long operation time, probably the best energy source is the solar panels (even though, this restricts the operation zone).
No, you just need more Plutonium. Solar panels also degrade over time.

Offline Jim

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Re: Long life probes for exploration of the Solar sytem
« Reply #9 on: 06/11/2018 01:30 PM »
Sorry, my fault, I was not specific enough. Of course when I wrote about tank station, I meant it being in a proper orbit not"far" (deltaV) from the probes it is serving.


Still not really viable.  Too much propellant would be wasted to rendezvous with the tank station.

Offline chipguy

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Re: Long life probes for exploration of the Solar sytem
« Reply #10 on: 06/11/2018 03:58 PM »
I think the discussion of power supply and propulsion for an
extended life probe so far misses the key problem.

The purpose of a probe is to position sensors and imagers
within range of interesting objects. These instruments tend
to ride the latest advances in technology and improve at a
fast pace.

The key drawback of a long life probe is the sensors and
imagers become obsolete compared to what would outfit
over time a series of cheaper lighter, single purpose, single
use probes.

Offline AegeanBlue

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Re: Long life probes for exploration of the Solar sytem
« Reply #11 on: 06/11/2018 05:53 PM »
The main issue with long living probes is not so much consumables as much as technological obsolescence. The Voyagers have cutting edge technology of 1972-3. By the time they made it to the launchpad in 1977 they were mid range technologically. At Neptune they were an old quaint system. Today they are more of a relic, worthy of a museum, that because of their location though bring about new science and new knowledge. Their cameras, turned off since Neptune, are Return Beam Vidicons, not CCDs, with all sorts of saturation issues. Their computer memory is so small that they sent out several programming changes during the planetary encounter because the computer could not do all the jobs all of the time. Let's not even start about their tape drive, whose minimum playback speed is faster than the current upload capacity of the radio transmitter, plus computer memory is so low data cannot be buffered there, data is simply lost every day. Some 6 times a year both Voyagers play back their recorded fields and particles data but not the whole thing, only what can be sent because of the bottlenecks in transmitting. On top of that their OS is so old, when someone retires or dies from the team they get replaced by someone often of the same age because only they know coding languages so obsolete. I love the Voyagers, but time and extreme distance takes its toll. Last year they said that they may be able to push them to get science back all the way to the 50 anniversary of the launch. Still we are seeing the difficulties.

On top of that the other example I would give is Landsat 7: Back in 2003 there was the scan line correction failure. Images that come back since 2003 have a Venetian blinds effect, losing a little under 40% of the image at the edges. At least resolution and sensors are not so much an issue, because Congress at the direction of the EO community has mandated that Landsat in order to keep forward and backwards compatibility will be at 30 m pixel. Landsat 7 is the target of NASA's refueling project. Sure, we will get more fuel, but we will also still get SLC-off images.

Offline jee_c2

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Re: Long life probes for exploration of the Solar sytem
« Reply #12 on: 06/13/2018 07:18 AM »
... tank station, being in a proper orbit not"far" (deltaV) from the probes it is serving.
Still not really viable.  Too much propellant would be wasted to rendezvous with the tank station.
Probably, you are right. It  depends on the "distance" of the two spacecrafts. It really narrows down the range of usability of such a solution. May be even to zero. I think, one application could be (if) the asteroid belt. There should be more tank stations, serving a lot of probes , which could make standard examinations, measures on the asteroids for mapping the belt for later mining activities.. I try to write a simplified simulation to find out the numbers.

It looks like, we should rather think about some propellent less drive like solar sail or Mr.Zubrin's dipol drive.. which also add more restrictions off course.

Offline rdheld

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Re: Long life probes for exploration of the Solar sytem
« Reply #13 on: 06/13/2018 11:16 AM »
so better to have shorter faster  missions?

Offline jee_c2

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Re: Long life probes for exploration of the Solar sytem
« Reply #14 on: 06/13/2018 05:00 PM »
In general we can say, that the current systems are about the best options for an optimization task result. This optimization task has some directives, some targets. Let's say creating a probe, which has specific tasks at a specific location (or more locations along it's well planned route), for that it should has the available best, latest instruments. Usually it will have the right amount of fuel to reach it's target (or to make a flyby there).

Comparing to it, the question is, if there is room and/or need for other type of probes, for which having the latest components, sensors is not so important, but it is important that the probe could visit lot of different targets, or could be quickly made available for examining something newly found. This is a bit similar to the question of using RLV or ELV. A different approach with a bit different targets, aiming optimization on different questions, parameters.

Optimization on the biggest delivered scientific value? Or economic value? (I.e. knowing which asteroid is worth mining?) Also a parameter, how fast do we want the results?

Offline whitelancer64

Re: Long life probes for exploration of the Solar sytem
« Reply #15 on: 06/13/2018 05:51 PM »
... tank station, being in a proper orbit not"far" (deltaV) from the probes it is serving.
Still not really viable.  Too much propellant would be wasted to rendezvous with the tank station.
Probably, you are right. It  depends on the "distance" of the two spacecrafts. It really narrows down the range of usability of such a solution. May be even to zero. I think, one application could be (if) the asteroid belt. There should be more tank stations, serving a lot of probes , which could make standard examinations, measures on the asteroids for mapping the belt for later mining activities.. I try to write a simplified simulation to find out the numbers.

It looks like, we should rather think about some propellent less drive like solar sail or Mr.Zubrin's dipol drive.. which also add more restrictions off course.

There have been proposals for a "grand tour" of the main asteroid belt, like Dawn, but doing flybys of many asteroids instead of going into orbit. Fuel needed for dV changes can be kept low by using the asteroids' gravity to adjust the orbit.

I thought it was a great idea, though the proposal to fly by many of Jupiter's trojans (the LUCY mission) was selected instead.

Similar to your thoughts, I think.
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Offline jee_c2

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Re: Long life probes for exploration of the Solar sytem
« Reply #16 on: 06/13/2018 06:20 PM »
There have been proposals for a "grand tour" of the main asteroid belt, like Dawn, but doing flybys of many asteroids instead of going into orbit. Fuel needed for dV changes can be kept low by using the asteroids' gravity to adjust the orbit.

I thought it was a great idea, though the proposal to fly by many of Jupiter's trojans (the LUCY mission) was selected instead.

Similar to your thoughts, I think.
Yes, and I also like the use of asteroids for changing course.
For commercial value, for mining map the Belt sounds better, but may be the Troyans promise more science value. Hard to tell.

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