My basis for the guess being the cost of deep space missions, the general lack of interest in deep space missions and the inherent cycle times between probes to particular planets.
My guess post dates yours by 20 years because I think there will be gaps on some of the 'easy' to get to ones like Mars for a time while there are ones out at Neptune or whatever and it will take 15 years of wrangling to get a third generation orbiter in place. I think I'm being optimistic about it though.
If anywhere, I'd say Mars is the least likely to have a gap - it seems able to get public interest (such as it is) in a way that Venus and Mercury don't, and it's a relatively benign environment.
The most likely "gap" is, I suspect, Mercury - very easy to argue there's not much payoff from sending another orbiter, and a relatively short lifespan once you get there.
Yep, that was the reason I pushed my answer forward ten years over my initial choice. I suspect there will be multiple probes around the Sun before Mercury gets one for itself.
I would only anticipate your answer being the correct one if human space flight were scrapped in favor of a big program of orbiters.
Oh, and I feel that I'm being pretty optimistic with my 2090 guess. I would not be surprised if due to the inevitably limited lifespan of machines that humanity never has orbiters around all eight planets at the same time.
I don't know why there would be orbiters around all of the planets at the same time. It would involve a serious committment of time and resources, and without a compelling reason I don't know why anyone would do it. It might happen by coincidence if there were multiple agencies involved, so perhaps my answer should be post-2200 rather than never.
Indeed. I expect the cost of sending an orbiter is only going to go down slowly, and the expected lifetime is going to increase but not that quickly, and so it seems that for rather a while it's not going to be an efficient use of resources to have orbiters around any given outer-gas-giant planet continuously. In addition, the cost is significantly lower if you do flybys from one planet to get to the next, so it's questionable whether it's worth frequently sending separate orbiters to Uranus and Neptune rather than generally sending joint missions that fly by Uranus a few times before heading to Neptune.
This may change if we start putting landers on moons, I suppose; a significant part of the reason we have continuous orbiters around Mars is for lander communication. But it's not clear at this point that there are many gas-giant moons that will support long-lived landers and are interesting enough to warrant sending multiples of them. Maybe Titan, which means you'd be likely to have a longer-term Saturn orbiter.
This. I can't see the economic sense of having landers on at least one moon of Jupiter, Saturn, Uranus, and Neptune simultaneously, thereby requiring simultaneous orbiters. I can foresee the possibility, perhaps in a scenario where space science takes the form of a four-way Great Power rivalry, but as a rational economic proposition it leaves much to be desired. However, you can't send landers to Venus with foreseeable technology, and I'd expect everything you can learn about Venus with orbiters to be wrapped up within a few decades.
I reserve the right to change my answer if inner system orbiters come within the budget of individual universities, which would bring the opportunity to make spurious economic decisions regarding same to thousands of actors.
At least two Venus near-term landing missions are seriously being planned even as you read this - the Venus In-Situ Explorer (VISE) and the European Venus Explorer (EVE). At least one has a reasonable chance of being funded. You can also find more speculative but not completely nutty plans on the web for nuclear powered long-term Venus rovers.
Also, even if landers remain short-lived, the most interesting exploration of Venus might be done by long-lived balloons. Balloon exploration of Venus has has already been done once, and there are plans to do it again.
Finally, I can't believe that everything you can learn about Venus will be learned within a few decades - Venus has quite a few mysteries already and I'm confident there will be more mysteries as we learn more. For now, as a lay person, I have these questions: Where did the water go? Were there oceans? Did the surface really re-form all at once, and when, and why? Did life ever start there? Is there life in the upper atmosphere even now? What's that weird radar-bright stuff on the Venusian mountaintops? I'm looking forward to finding out!
I can see a scenario where you have orbiters in place around, say, Io to teleoperate the machinery that actually touches down on the surface. The same for the Planet formerly known as Pluto. Pathfinder-style rovers that can survive in either of these types of environments would tend to be expensive, I imagine. Far better to have someone on-sight to make sure they don't drive into a cauldron of steaming water rather than rely on AI to accurately gauge and avoid hazards.
In addition, the cost is significantly lower if you do flybys from one planet to get to the next, so it's questionable whether it's worth frequently sending separate orbiters to Uranus and Neptune rather than generally sending joint missions that fly by Uranus a few times before heading to Neptune.
How can something doing a flyby of Uranus on its way to Neptune get more than one pass at Uranus?
I was thinking of something that entered a (probably relatively eccentric and large) orbit and then exited it again, rather than a gravity-assist sort of path.
I didn't actually think about this long enough to figure out whether that was actually a plausible scenario. I suspect it isn't, though.
So, it was a revelation to me that Cassini could use Titan to leave the Saturn system and head back to Jupiter. How about this: a probe that flies by Uranus, enters an orbit around Neptune, and then, after a suitable number of orbits exploring the Neptune system, uses a Triton flyby to go back to Uranus and either does a flyby or start orbiting there. I'm not doing any math here, or even any internet lookups (in favor of a very quick reply), but I would suppose that Saturn:Titan sufficiently scales down to Neptune:Triton to make this possible.
Indeed. I expect the cost of sending an orbiter is only going to go down slowly,
It may be more efficient to focus on growing the economies paying for the probes rather than trying to bring the probe costs down (But if anyone wants to mass-produce probes, I am OK with that).
I have no idea, but I think I've been immersed in history too much lately, because I thought, "Wait, eight planets, that doesn't sound right..." (pause, in which anyone else would say "But there are nine!") "Isn't it actually seven?"
By this do you mean when will we likely have simultaneous orbiters around all eight planets, or when we will have put orbiters around all eight planets? The latter is probably within thirty years, considering that we're only missing Uranus and Neptune. The former is going to be when it's worthwhile having permanent orbiters, and when we figure out how to actually do that with Mercury, which is an indeterminate amount of time.
How hard is it to get a long term orbiter around Mercury? How fast does the Sun perturb any satellites there? I don't foresee a long term orbiter there unless we have some reason to put one at a Lagrange point.
I'll go with never, being rather pessimistic about the prospects for impending environmental, economic, and social collapse, pandemic, class warfare, (insert your preferred, clichéd gloom & doom here) ....
Never is such a long time, even for doom and gloom. After all, James recently posted a blog entry about a pretty drastic doom-and-gloom scenario -- the complete extinction of the human race, and yet he entertained the notion of not just one but many intelligent tool-using successor species... ...so cheer up! The intelligent rat-people who replace us might have a really inspirational space program!
Somewhat to my own surprise, I voted "Never". It's taken >50 years to get this far, and we might be at or past the peak.
Given that very soon now, the US will no longer have a manned space program, I'm feeling pretty pessimistic about the future of space exploration in general.
Mercury reason #1: Instead of using orbiters at Mercury, Robert Forward's Statite's might be used to hover such that they are constantly in the sky above the more useful polar regions.
Mercury reason #2: Some of the people commenting above wondered what need there would be to have orbiters simultaneously around each planet. One reason involves climate change here on Earth. I'm not a climatologist, but I imagine that it would be useful to understand the sun's effect on the atmospheres of each of the planets, so that we can better distinguish between the effects of the sun, and other terrestrial causes of climate change ("Beware the beast man, for he will make a desert out of his home and yours....") I'm thinking of this system-wide monitoring as taking place in a moderately far-off future where future tech makes things a bit easier. But Mercury, being atmospherically-challenged, might be the one planet where we wouldn't monitor the sun's effect - so Mercury would be the spoiler, and we'd only have 7 of 8. On the other hand, as Pluto's atmosphere resurrects itself (the atmosphere comes and goes at different points in its orbit), we might be monitoring its atmosphere instead, so we'd still have 8 orbiters around objects historically thought of as planets. And maybe we'd want to monitor the atmosphere of Titan, and maybe even Triton's too.
Alternatively: Despite Uranus' tilt, despite its rings, despite Mirada's deep canyons, and despite Uranus' other various unique features, it might be viewed as the most boring of the planets, and I can imagine a time when it is neglected while each of the other planets is being simultaneously visited.
This is fun - it's a science-based elimination game! Mercury/Venus: I like the answers people have given above, but these are the hard ones to keep funding. Hmm. But in another 2-3 funding cycles, the Decadal Surveys might think about them again. Earth: well, guaranteed. Mars: ditto. Jupiter: Juno to launch very soon. Europa if you're into the long-term payoffs (and depending where this decade's Europa/Titan fight goes; by the next 3 funding cycles, guaranteed to get them both). Saturn: Titan, Titan, Titan. And Enceladus. Frankly, you're going to have to drag people away from this one if you want them to stop looking at it. Uranus: If the Cassini crowd get another orbiter to go to Titan, we can send Cassini to Uranus for the better part of a decade. Neptune: Triton! We don't have to go to the Kuiper Belt to look at a KBO, and we can go into orbit instead of zooming by!
So all 8? Pushing it...but the ones that go to the outer Solar System in particular tend to be long-term missions. Anyway, the science will be more important than the simultaneity :)
Here's a paper (abstract and preview only) showing how Cassini could be redirected, via Titan flybys, to Jupiter, Uranus, or Neptune, or first to Jupiter and onward via Jupiter to Uranus, Nepture, and a Centaur, and then out of the system ala Voyager. But when this was discussed on unmannedspacefligt.com, the reaction was "WHAT? There is so much more science to do at Saturn, why would you ever leave?!" The people who are operating Cassini are pretty focused on Saturn, and somehow I think having a second probe at Saturn wouldn't lead them to think that Cassini shouldn't stay at Saturn. A bird in the hand.... ....on the other hand, it looks like the options for Cassini are still quite varied, and while some of them involve a death plunge like Galileo, other options include a very long term low-resource-usage wide orbit of Saturn doing seasonal observations of Saturn Titan, and Encelasdus, which means Cassini might yet play a key role in the glorious eight planets at once observation campaign. pdf.aiaa.org/preview/CDReadyMAST08_1856/PV2008_6753.pdf
On a more sierous note, one of the things that may just limit the amount of simultaneous deep space missions might not be the cost of the orbiters themselves or the lead times, but the amount of staff you need on the ground to guide the mission and digest the data coming back. NASA or ESA personell budgets are not infinite after all.
Here's a fast mission to explore a planet's poorly understood geology.
I once did a little research trying to figure out what sort of devices could function for extended periods in molten iron, and there are a few things, like immersion sensors, that the steel industry uses. Stevenson, like Landis, proposed Stirling coolers.
I picked 2050 because A) it's a semi-round number, and B) I enjoy being optimistic about sending unmanned stuff into space. But I certainly am not envisioning NASA (or The Big Governmental Space Agency of 2050) having 8 simultaneous orbiters.
ion engines mean cheap small probes are quite likely, and will be more and more common - also the energy cost for a mission will be less important with a SI in the tens of thousands. More countries in space, trying to get recognition means open slots will be rarer and rarer. So, really, I would have chosen 2020, but went conservative and chose 2050.
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The most likely "gap" is, I suspect, Mercury - very easy to argue there's not much payoff from sending another orbiter, and a relatively short lifespan once you get there.
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Oh, and I feel that I'm being pretty optimistic with my 2090 guess. I would not be surprised if due to the inevitably limited lifespan of machines that humanity never has orbiters around all eight planets at the same time.
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You mean, kind of like space exploration since the 1970's...
I didn't read the question as requiring orbiters around all eight planets at the same time. I guess I need to read more carefully next time. :-)
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This may change if we start putting landers on moons, I suppose; a significant part of the reason we have continuous orbiters around Mars is for lander communication. But it's not clear at this point that there are many gas-giant moons that will support long-lived landers and are interesting enough to warrant sending multiples of them. Maybe Titan, which means you'd be likely to have a longer-term Saturn orbiter.
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I reserve the right to change my answer if inner system orbiters come within the budget of individual universities, which would bring the opportunity to make spurious economic decisions regarding same to thousands of actors.
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I was thinking in terms of pure research, to be honest.
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Also, even if landers remain short-lived, the most interesting exploration of Venus might be done by long-lived balloons. Balloon exploration of Venus has has already been done once, and there are plans to do it again.
Finally, I can't believe that everything you can learn about Venus will be learned within a few decades - Venus has quite a few mysteries already and I'm confident there will be more mysteries as we learn more. For now, as a lay person, I have these questions: Where did the water go? Were there oceans? Did the surface really re-form all at once, and when, and why? Did life ever start there? Is there life in the upper atmosphere even now? What's that weird radar-bright stuff on the Venusian mountaintops? I'm looking forward to finding out!
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*boggles*
*checks the surface temperature of Venus. 740k.*
*reviews melting points on the periodic table*
Okay, I suppose I can see what sort of wheeled vehicle could rove upon Venus. Perhaps we will probe the other seven planets simultaneously some day.
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Yeah! Check out the Venus Future Missions thread in the Venus section at http://www.unmannedspaceflight.com/ for a discussion (I love that forum).
And this Wikipedia page cites a paper by the Geoffrey A. Landis (the name is probably familiar) on Venus rovers.
http://en.wikipedia.org/wiki/Observations_and_explorations_of_Venus#Future_missions
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How can something doing a flyby of Uranus on its way to Neptune get more than one pass at Uranus?
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I didn't actually think about this long enough to figure out whether that was actually a plausible scenario. I suspect it isn't, though.
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It may be more efficient to focus on growing the economies paying for the probes rather than trying to bring the probe costs down (But if anyone wants to mass-produce probes, I am OK with that).
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If the question is at what time will all of them have or have had orbiters, I'll guess 2100.
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...so cheer up! The intelligent rat-people who replace us might have a really inspirational space program!
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Given that very soon now, the US will no longer have a manned space program, I'm feeling pretty pessimistic about the future of space exploration in general.
Blame Mercury
Mercury reason #1: Instead of using orbiters at Mercury, Robert Forward's Statite's might be used to hover such that they are constantly in the sky above the more useful polar regions.
Mercury reason #2: Some of the people commenting above wondered what need there would be to have orbiters simultaneously around each planet. One reason involves climate change here on Earth. I'm not a climatologist, but I imagine that it would be useful to understand the sun's effect on the atmospheres of each of the planets, so that we can better distinguish between the effects of the sun, and other terrestrial causes of climate change ("Beware the beast man, for he will make a desert out of his home and yours....") I'm thinking of this system-wide monitoring as taking place in a moderately far-off future where future tech makes things a bit easier.
But Mercury, being atmospherically-challenged, might be the one planet where we wouldn't monitor the sun's effect - so Mercury would be the spoiler, and we'd only have 7 of 8. On the other hand, as Pluto's atmosphere resurrects itself (the atmosphere comes and goes at different points in its orbit), we might be monitoring its atmosphere instead, so we'd still have 8 orbiters around objects historically thought of as planets. And maybe we'd want to monitor the atmosphere of Titan, and maybe even Triton's too.
Blame Uranus
Re: Blame Uranus
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Mercury/Venus: I like the answers people have given above, but these are the hard ones to keep funding. Hmm. But in another 2-3 funding cycles, the Decadal Surveys might think about them again.
Earth: well, guaranteed.
Mars: ditto.
Jupiter: Juno to launch very soon. Europa if you're into the long-term payoffs (and depending where this decade's Europa/Titan fight goes; by the next 3 funding cycles, guaranteed to get them both).
Saturn: Titan, Titan, Titan. And Enceladus. Frankly, you're going to have to drag people away from this one if you want them to stop looking at it.
Uranus: If the Cassini crowd get another orbiter to go to Titan, we can send Cassini to Uranus for the better part of a decade.
Neptune: Triton! We don't have to go to the Kuiper Belt to look at a KBO, and we can go into orbit instead of zooming by!
So all 8? Pushing it...but the ones that go to the outer Solar System in particular tend to be long-term missions.
Anyway, the science will be more important than the simultaneity :)
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pdf.aiaa.org/preview/CDReadyMAST08_1856/PV2008_6753.pdf
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Also, the University of Arizona just got done running Mars Phoenix, and now they are looking forward to running more space missions:
http://www.cnn.com/2008/TECH/space/06/26/arizona.mars/index.html
Grad students are cheap! :-)
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I once did a little research trying to figure out what sort of devices could function for extended periods in molten iron, and there are a few things, like immersion sensors, that the steel industry uses. Stevenson, like Landis, proposed Stirling coolers.
The spin-offs seem obvious.
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So, really, I would have chosen 2020, but went conservative and chose 2050.