While the likelyhood of a Mercury Lander mission is very low, I was wondering if any planning/studies have been done on such a project?
The European 'BepiColumbo' mission planned for the next decade included a lander at once point, but it was cut. I believe this mission also included multiple orbiters and a collaboration with JAXA... but I'm not sure off the top of my head.
I don't see why it would be particularly difficult.. as long as it landed either during the day or the night.. I can't imaging a spacecraft withstanding the temperature difference between them.
Impactor could work
Doug
ESA studied alternative possible designs for a BepiColombo lander in great detail, until they concluded that they just didn't have the money. Meanwhile, the US has pretty firmly concluded that a Mercury multiple-small-lander mission is the only logical next step after Messenger and BepiColombo, although it's not all that high on NASA's Solar System priority list. (It would likely be a New Frontiers-class mission, costwise.)
Although the Bepi-Colombo lander is cancelled, ESA has spend some money on studies. So there are people building stuff that won't actually fly...
Well - studies dont equal flight hardware. Maybe some simulations, maybe some studies, some spreadsheets - but I doubt a single bit of metal was cut.
Doug
actually, hardware is actually made at this moment. However, they will make it such that it is also possible to use it on Mars, very conveniently
(1) That Mercury smash-and-grab mission is a real idea -- in fact (although I know virtually nothing about it), there was apprently at one point a Discovery proposal to do just that for one of Mercury's polar regions (to also try and obtain information on the polar deposit composition).
(2) Actually, it is thought likely that Mercury's regolith differs somehat in closeup appearance from the Moon's simply because meteoroids have been smashing into it at much higher speed. At a mnimum, there should be a lot more melted impact glass mixed into it. It's questionable, however, whether any such differences would be interesting enough to be worth a camera. But:
(3) A Mercury lander WOULD have a lot more uses. We very badly need to know more about the planet's strange internal structure -- for which seismometers, magnetometers, and (if possible) heat flow probes would be invaluable. In fact, just plain old measurements of the planet's libration rate by tracking a lander would be very informative about its interior -- Stanton Peale once suggested a Mercury lander that would do nothing else whatsoever!
And while we might be able to get good data on the element makeup of Mercury's crust from a smash-and-grab mission, there are also some important mineralogy measurements (Raman, Mossbauer, X-ray diffractometry) that could probably be done neitehr by such a mission nor by an orbiter. Finally, a surface lander might tell us more about the planet's super-rarified atmosphere than we could discover from an orbiter.
[quote=BruceMoomaw,Aug 16 2005, 07:53 PM]
(2) Actually, it is thought likely that Mercury's regolith differs somehat in closeup appearance from the Moon's simply because meteoroids have been smashing into it at much higher speed. At a mnimum, there should be a lot more melted impact glass mixed into it. It's questionable, however, whether any such differences would be interesting enough to be worth a camera.
I cannot imagine sending a lander to a planetary body without a camera! It would be interesting to see if the character of the surface varies from the Moon, and if there is a lot more impact glass than the lunar surface one would expect a more pronounced heliogenshein effect than what one sees on the Moon. The higher gravity might cause slightly different crater details on the small scale.
Don Davis
Well quite - of the planets on which one COULD land - it is only Mercury and Pluto from which we dont have surface imagery
Doug
You're forgetting 2003 UB313, Doug... (Or, alternatively, The Planet That Must Not Be Named. Come to think of it, I hope the Potter craze hasn't gone so far that they end up naming the thing Voldemort.)
JRehling,
your smash and grab idea is interesting. It could be perhaps beterred if the impactor hits the surface with a very low angle, nearby horizontal, so that the plume would be also nearby horizontal. And the main spacecraft would travel right in at low relative velocity, we could perhaps even collect more than dust, little stones.
BruceMoomaw,
just to get the exact movement of Mercury from a lander would require only little electronics for that lander, just retro rocket and guidance devices, and avoiding heat by landing at night. The payload itself would be just a mirror, similar to the ones placed on the Moon, so that it could easily withstand heat and need no electronics, insulators and the like.
A still simpler method, although more speculative, would be to send special reflecting glass balls, protected into a kind of low melting point metal or plastic, and shot this on the ground without retrobraking. With a low enough impact velocity, the casings protects the glass balls. (An additionnal idea would be to fly the glass balls just behind a larger impactor, so that the plume would brake them). Once the sun rises, the casings melt, lefting the glass balls naked, so that they could be used for measuring distance with a laser shot. Not all glass balls would work, but if we send many a fair amount could work. This is not worse than landing the MERs into an airbag!
The idea of a lander on Mercury or Venus arises special concerns, due to the extreme heat. Maybe I shall start a thread about the suitable technos for this.
[quote=DDAVIS,Aug 16 2005, 03:30 PM]
[quote=BruceMoomaw,Aug 16 2005, 07:53 PM]
(2) Actually, it is thought likely that Mercury's regolith differs somehat in closeup appearance from the Moon's simply because meteoroids have been smashing into it at much higher speed. At a mnimum, there should be a lot more melted impact glass mixed into it. It's questionable, however, whether any such differences would be interesting enough to be worth a camera.
I cannot imagine sending a lander to a planetary body without a camera! It would be interesting to see if the character of the surface varies from the Moon, and if there is a lot more impact glass than the lunar surface one would expect a more pronounced heliogenshein effect than what one sees on the Moon. The higher gravity might cause slightly different crater details on the small scale.
Don Davis
JRehling observed " We probably have, or will have, Mercury meteorites in collections "
Maybe but it's doubtful. They'll look, in all probability like lunar highlands breccias, but bulk compsition will be obviously non-lunar... a different pattern of volatile element depletion from what we think really heavily stripped the moon of "volatile" elements, including things like potassium, halogens, lead, zinc... in the mega impact that lead to our double planet.
More distinctive, and telltale, will be oxygen isotope fractionation patterns. The solar system was mixed thoroughally, but not completely, and martian, earth/moon, asteroidal (many different batches) and cometary isotopes are utterly distinctive in an 016/17 vs O16/18 plot.
There is *ONE* oddball meteorite I read about 2 or 3 years ago that resembles lunar meteorites but has an odd oxygen isotope pattern and it was being discussed as a possible mercurian ejecta sample, but I haven't heard a peep in the public reporting since.
Expectations, as I recall, from orbital dynamics stuff is that we should get about 1 merc meteorite for every 100 lunar ones <separate impacts?>.. and we dont' have 100 lunar ones.
Where we *should* put a lander down is on the mercury polar ice deposits in permanent shadows in craters. Keeping the lander warm will be the problem, not cool. This stuff is radar-bright and depolarizing.. the radar penetrates many wavelengths into the scattering ice without being absorbed and gets diffusely scattered back out with high reflectance.
Utterly unlike the marginally detected radar signature of lunar polar volatiles, if the detection claims aren't bogus anyway.
What is astonishing with Mercury is that it closely ressembles the Moon, but it does not seems to have volcanic activity, despites the fact that Mercury is much larger than the Moon. The Moon hade huge lava flows about 3-3.2 Gyears ago, forming the "seas". But as fas as I know there are no traces of lava or volcanoes. A popular hypothesis about these lava flow is that they were produced by the cooling and closing of the inner liquid core. But I think the hypothesis of a tidal heating would be interesting too, while explaining why Mercury had not such a volcanic episode.
Another difference (perhaps explaining the lack of volcanoes) is the huge iron core. There is also the network of NE-SW and WN-ES fractures running all around it. A popular hypothesis is that these fractures are due to the shrinking of the iron core when it cooled, perhaps at the occasion of the large impact of Mare Caloris.
If getting a refector on Mercury is the objective, how about an impactor filled with thousands of tiny reflective devices -- like confetti -- that are released on impact to cover a large surface area? Or, a giant paint ball that would splat on the surface, coating it with reflective paint?
Here is a recent study of the probability of finding a mercuriam meteorite:
http://www.lpi.usra.edu/meetings/lpsc2003/pdf/1933.pdf
The conclusion is that probability-wise "we may be getting close..."
tty
We don't want a reflector on Mercury for libration studies -- we need an actual, stationary surface beacon for reeally good measurements. (Remember that this was considered a worthwhile experiment even for the Mars Netlander -- and studies of Mercury's libration are thought to be more important.)
Certainly, when a Merury lander finally occurs, the first one will be in the polar regions (the BepiColombo lander would have landed at about 87 deg latitude). This isn't just because of the polar deposits; it's because that's the one part of Mercury where a lander can have a really long lifetime -- which is crucial for seismic studies.
Cant but agree with BruceMoomaw, libration studies is one good reason, the other is my own favourite, seismic. All we have about Mercurys interior currently is quesswork, informed guesswork perhaps -but still.
A lander might have to be assisted by a set of impactor probes, at least two.
If such a lander also would get some more toys to maximize the science return like a little shovel, a chemistry set and one Polaroid to imagine the polar-void - all the better.
centsworth_II your idea is interesting, but it would not work as it: glass balls or paint drops arriving on Mercury surface at a cosmic speed would simply explode like meteorites. They need some kind of braking, if not an actual landing. For example they could be dropped on the ground from a low orbit.
But that would not be enough, says BruceMoomaw. So what do you need? an accurate reflector like the ones the astronauts installed on the Moon? I recall that these reflectors were made of an array of diamond-shaped pieces of glass, which has the property of sending back any ray of light right in the direction where it came. This is much more accurate and much more efficient (a much larger part of the light is reflected back to the emitter) than with just randomly scattered glass balls. But an already powerfull laser is required to shot at the Moon reflectors; 12 000 000 000 more power would be required to have Mercury with the same devices. This is perhaps the reason why there was no light reflectors on the top of any of the already numerous Martian landers.
So BruceMoomaw, what do you need? A radio beacon? It would be much more efficient in power, but less accurate. May an orbiter provide enough accuracy? After all, much info on Mars position may be infered from the radio wave emitted by Mars landers and orbiters, much more anyway than with nothing. So I understand that at least an orbiter around Mercury would provide much more data than nothing. And a lander still more.
The ideal would be active laser telemetry (a lander-based laser would reply to an Earth based one) but this would imply to send power lasers in spaceships. Let us have a dream: a powerfull laser geodesic network allowing to know the position of any planet with a micron accuracy...
I honestly don't know why they had it in mind, but Stanton Peale's scheme would definitely have involved an active radio beacon. (This is more easily understandable for the Mars Netlanders, since laser reflectors on Mars would quickly get dust-coated.)
Well, I know that, John. I presumed that Richard Trigaux (like myself) was thinking about a surface reflector with an orbiter bouncing lidar off it -- just as the libration experiment on the Mars Netlanders would have involved a radio receiver on a Mars orbiter. But I still don't know why such surface laser reflectors (or radar reflectors) couldn't be used in association with an orbiter for Mercury libration measurements.
ESA was thinking about a lander only 3 degrees from the pole, but NOT in shadow. If I remember correctly, they hadn't quite ruled out powering (and heating) it with a small RTG, which of course WOULD make a shadowed-area landing possible. But the purpose of the lander was to get a better geological understanding of Mercury in general -- not of one of the polar deposits in particular.
Just throwing out some ideas, may be helpful in the long run.
The amazing trajectory Messenger is taking to Mercury would be reversible, wouldn't it? I'm thinking an orbiter/lander could be sent to Mercury (granted this part is going to be heavy) to study the planet, and the lander could collect some surface samples and put them into orbit around Mercury.
A retreiver craft could be sent to collect the samples and then return to earth via a reversed version of the Messenger flight plan.
The key to making this work is that you set it up so that as much of the delta v as possible is provided by gravity assists from Earth, Venus, and Mercury for all the spacecraft involved in the mission.
Also,
To expand on some of the ideas posted in this thread, could a kevlar net orbiting Mercury (tethered to a shielded orbiter) 'snag' debris from a plume generated from an impactor craft?
This might be a 'cheap and dirty' way of retrieving materials from the surface of Mercury as part of mission to return them to earth.
There was, I've heard (though I haven't confirmed it), a smash-and-grab Mercury sampling mission once proposed for Discovery. Meanwhile, the ESA has actually done the preliminary design for a full-fledged Mercury landing and sample return -- although they also did so for Venus, which may give you some idea of how politically realistic the plan is. I'm convinced that, given their cost, it will be a long time before we see a landing and sample-return mission from any large world that doesn't have possible biological evidence -- that is, Mars and (in the longer run, if previous landers turn up something interesting) Europa.
Two or three years ago, there was some reporting on an odd meteorite that had distinctive isotope patterns and chemistry. There was some speculation it was Mercury ejecta, but that interpretation didn't seem strongly favored. I don't recall it's name/designation. I've heard no further discussion of it, and have wondered what the status on it is. Meteoritical Society meeting abstracts may have contained something but I haven't broused them extensively.
I can't find the reference to the Mercury smash-and-grab sample return either, although I had found it on the web a couple of years ago. It was a real "outsider" proposal, conceived from someone not really working in space exploration, IIRC, and I don't know if it was an official Discovery proposal or not -- yet it is a solid idea. Certainly this kind of sample return is not as useful scientifically as having a rover move around and delicately select a geologist's wishlist, but what this kind of mission lacks in benefit, it makes up for in cost savings.
NWA 011 is the name of the meteorite that was speculated upon as being mercurean in origin. Here are some discussions of the item's origin, however, that don't even mention the word "Mercury", FWIW:
http://web.utk.edu/~lataylor/pub-list/Floss-1153.pdf
http://www.lpi.usra.edu/meetings/lpsc2004/pdf/1094.pdf
http://aaa.wustl.edu/Work/pub_files/northwestafrica011.html
There can only be so many rocky parent bodies in our solar system's past/present that were large enough to exhibit major radiogenic heating, and Mercury is one of them. Perhaps we'll end up with an exhaustive list one day and identify the Mercury meteorites by elimination. But we're not close to that day...
A smash-and-grab sample return would not only have its own value, but would also possibly clinch the identification of Mercury meteorites in our possession. In terms of delta-v, we more or less need a solar orbit that has aphelion at 1 AU and perihelion at 0.48 AU -- that is more delta-v than a Venus/Mars lander, but then the craft would essentially be an Earth lander without instruments. It would be highly desirable to perform remote sensing of the impact site, a la Deep Impact -- the instruments should perhaps be mainly contained on the impactor, since instruments on the return craft wouldn't have any use after the impact while flying back to Earth.
Keep in mind that this thing will fly past Mercury at damn high speed, and thus its sample grains may be largely melted. However, since a comparably high-speed flyby of Europa is considered scientifically worthwhile, I presume one of Mercury is too.
In this 1971 book, Beyond the Moon: Future Explorations in Interplanetary Space
by C. B. Colby, there is a chart of then future planetary missions:
http://sun3.lib.uci.edu/~jsisson/beyond.htm
For Mercury, they indicate an orbiter for 1982. Was there ever an actual plan
to orbit Mercury in the early 1980s?
Of course the chart also declares a manned lunar base in 1978 and manned
expeditions to Venus and Mars in 1982 and 1981, respectively.
NASA never -- and I mean never -- put any Mercury orbiter anywhere in even the also-ran listings of its desired future planetary missions, until Chen-Wan Yen, in the late 1980s, came up with the complex but workable kind of multiple gravity-assist flyby setup that Messenger is now using. Until then it was thought to be far too expensive and complex for what (to quote Ken Croswell in 1991) "isn't a sexy planet." Indeed, I didn't hear a peep about Mercury as a possible high-priority target until the Discovery Program AOs started.
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