Japan And EU Plan Joint Mission To Mercury

Devar writes "Japan and the European Space Agency have revealed their plans for a joint mission to Mercury that would be the first to land a probe on its surface. The mission also includes two orbiters to map the surface, all due to be launced in 2010."

Re:Joint mission?

[mess31173]

Avg. Surface temp. (of mercury): Day 623 K Source [wikipedia.org]

That's hot enough to keep it lit. And get you fried, in this case, in more ways than one.

Re:Joint mission?

[Scarblac]

Firstly, of course the moon rotates as well. It just rotates at the same angular velocity at which it orbits Earth, so we always see the same face. This is caused by a process called tidal lock.

Mercury is in tidal lock with the sun. But because its trajectory is elliptical, it's not a 1:1 lock, but a 3:2 lock: there are 3 Mercury days in 2 Mercury years.

A Mercury day is 58.6 Earth days, a Mercury year is 88 Earth days, according to this fact sheet [the-solar-system.net]. 58.6 days should be enough for most missions.

Re:Why Mercury?

[Paul Neubauer]

There have been many missions to Venus and Mars, a few flybys of Jupiter (and Galileo orbiting Jupiter). Saturn and beyond have only flybys so far, but it takes a long time to get to them. Mercury is relatively close, is close to the sun so solar power can be used (avoiding silly controversy over nuclear power sources) and has only had one spacecraft look at it, from mainly one angle. Also, it's not the moon, but a "new" world to explore. All in all, it's a nice place to send a few robots to prove one's technology and show off, and get useful new results in a reasonable amount of time.

BepiColombo

[FlexAgain]

Even though they don't mention the name, this sounds likes they are talking about BepiColombo [esa.int] which has been in the works for several years now.

One of the more exciting bit about the mission is the lander (or impactor, depending) which is one of the things which distinguishes it from the US Messenger. Unfortunately, this is also one of the elements most likely to be removed, due to cost and complexity.

Re:Why Mercury?

[FlexAgain]

Why did they choose Mercury? Don't get me wrong, I think it's pretty cool, but why not some of the other planets in our system? Scientists are fascinated with Mars because of the possibility of life. There's fascination about Saturn and it having a bazillion moons. Jupiter with it's nutty red spot (man that's a hell of a storm).

Well, at the moment, ESA has a mission going to Mars (Mars Express), Venus shortly (Venus Express), Saturn is covered by Huygens (in combination with Cassini).

Nothing is going to Jupiter, Uranus, Neptune, or Pluto at the moment, but most of those are real buggers to get to easily.

Mercury is the only planet in the inner solar system which ESA hasn't sent anything to yet (or is about to). Add to that the fact that so little is known about it, Mariner 10 left many questions unanswered, and it's about time we had a look.

Re:Why Mercury?

[cjabaley]

For a low cost mission Mercury is probably your best bet. There's no atmosphere to speak of, and external propulsion won't have to be terribly elaborate, because the sun's gravity will do most of the work. Also, as the two posters above me mentioned, very little has been studied about Mercury. On a more scientific note, mercury is the perfect place to study the effects of extreme heat and gravity on a planet and the inorganic substances that exist there. Moreover, it can provide more information about the level of radiation bombardment that could be expected for objects passing close to the sun.

Re:Why Mercury?

[darkwhite]

All in all, it's a nice place to send a few robots to prove one's technology and show off

It is, the only problem being that it's really, really hot. As far as I understand, you have to have a reflective shield turned to the Sun at all times, and even so, your electronics are in for a very rough ride. This makes soft-landing much harder for surface probes, unless you land on the shaded side. Impact landing should be easier, but doesn't collect nearly as much information. Even worse, once you soft-land, you'll have to shield yourself from both the Sun and the ground, which makes rovers all but impossible, and soil sampling hard, too. (But if you land on the shaded side, those problems should go away.)

Also, it takes half a year to fly to Mars, but Mercury requires an elaborate orbit injection trajectory: the MESSENGER probe will spend 4 years before injection. So in terms of PR returns, it's probably better to keep sending stuff to Mars, especially because there's more to explore there. (Certainly no carbon-based life on Mercury, except maybe in craters with permanent shadow...)

Re:Joint mission?

[RodgerDodger]

Seesh, did you read the proper answer?

A) Mercury does rotate. However, your "proper answer" got it wrong; while Mercury rotates on its axis every 58.6 days, it's moved a long way around the sun in that same time. As a result, it's day (period between one sunrise and the next) takes longer than its rotation period [arizona.edu]. In fact, it takes about 3 rotations to get one 'day'. Also, because of the elliptical orbit and long rotation period, you can get a funky double-sunset effect [nasa.gov], when the sun sets, then rises again in reverse before setting again.

B) Mercury does so have an atmosphere [the-solar-system.net]. The atmosphere is, on average, about 440K; quite hot enough. The night side is cold, not because there is no atmosphere, but because the atmosphere is so thin it radiates the heat away into space very fast. Mercury actually has a very turbulent convenction system, especially around the terminator line.