Riding with Robots writes "Today, more than three decades after the last spacecraft visited Mercury, Messenger buzzed just 200 kilometers above the planet's surface. During the encounter, the robotic spacecraft conducted a range of scientific observations, including imaging swaths of Mercury's surface that have never been seen up close before. A few of the first pictures are now available, with many more to come in the next few days."
Just as in Biology, a lot of what is observed in Astronomy is what's big, pretty, and easy. Venus and Mercury are two planets that are largely unappealing by normal standards - way too hot, completely dead and barren. It's always good to see good science being done for the sake of science, not public opinion. Cassini and the rovers were fantastic, but the less glamorous missions are just as important to our understanding.
Part of the problem, too, is that it's really tricky to get to Mercury due to the amount of delta-v you need to shed Earth orbit, plus unlike Mars, Mercury has a negligible atmosphere which makes aerobraking useless. That's why they did three slingshot maneuvers to get there. The navigation team at JPL has really outdone themselves with this flight, and are to be commended.
It actually takes more delta-v to get to the sun than it takes to leave the solar system from here. This is why that whole "send dangerous waste to the sun" is a really bad idea. It takes a huge amount of fuel and if you miss, you've got a dangerous payload in a highly eccentric orbit that almost certainly crosses the Earth's. What could possibly go wrong?:-)
And maybe it's because I'm a space nerd, but I think MESSENGER is glamorous as hell.
Perhaps you could clarify something for me. After you break earth's orbit, why would it take any extra energy to get to the sun? (This is assuming of course that the garbage is pointed at the sun and timed so it wouldn't get close enough to Venus and Mercury to divert it's course. Why would getting away from the sun be easier than going towards it?
And a solution to send garbage safely would be to aim it a bit high or low (perpendicular to orbit of Earth). The slingshot would almost never send it back towar
This is assuming of course that the garbage is pointed at the sun and timed so it wouldn't get close enough to Venus and Mercury to divert it's course. Why would getting away from the sun be easier than going towards it?
If you point it right at the Sun from ground perspective, it will just come back to circle the Earth unless propelled really hard. One needs to find a way to bleed sun-orbiting speed off of it. There's no free lunch.
Standard movement vector of solar wind (outward) is neglected (slides along the surface), and we're acting only in perpendicular direction, our orbital speed against "zero" component of the speed vector of the solar wind.
Solar sails do not use the solar wind (i.e. charged particles) for propulsion, but the light pressure (photons). Also, you can actually control the direction of the thrust gained from from the solar sail by changing the direction in which the photons are reflected (at the expense of absolu
Actually, pointing something towards the sun wouldn't really send your payload into the sun unless you pushed really, really, really hard. To get something to approach the sun using chemical rockets, one must think about the concept of an orbit. An orbit is defined by the object's speed around its central body. Thus, in order to get closer to the sun, your payload would have to drop its orbital velocity to near enough to zero, if you want a fast collision. You would need to use energy to get to the limit of earth's gravitational influence, about 1,000,000km out. At this point, you would essentially moving with the same orbital velocity as the earth with respect to the sun. Escape velocity for Earth is about 11km/s. With respect to the Sun, the Earth has an orbital velocity of about 48km/s. This means that to get you probe to go on a straight line to the sun, you would need 59km/s of delta v, which is a hell of a lot, and delta v is (essentially) directly proportional to amount of fuel you must carry. Now, granted, you could take a more circuitous route to arrive at the sun, and use less delta v, but it would still be a significant fraction of the 59km/s.
With regards to you second question, unless the highly inclined orbit was altered again at perigee and apogee with respect to the sun, your payload would return to the Earth's orbit.
Note: I am not a rocket scientist, at least not for a while, but I have done a bit of interplanetary stuff like this. All the numbers come from google. And it is entirely possible I'm quite mistaken, but I hope this was a bit helpful.
The answer is easiest to see in terms of angular momentum. (Orbits are really all about angular momentum, more so than energy.) If you break free of Earth's immediate gravity, you're still in pretty much the same orbit as the Earth going around the Sun. You have to dump a lot of that angular momentum to reach Mercury or the Sun, and that takes quite a bit of work. Remember, escape speed from the Earth's surface is around 11 km/sec, but the Earth's orbital speed is around 30 km/sec. You have to dump abo
That's why they did three slingshot maneuvers to get there. The navigation team at JPL has really outdone themselves with this flight, and are to be commended.
Interestingly enough, the navigation of this flight was outsourced to Kintex [kinetx.com]. The mission itself is managed by APL... AFAIK, JPL wasn't particularly involved.
Sort of. It was thought to be tidally locked, until they found out it rotates approx. thrice for every two revolutions around the sun. Mercury has quite a complex orbit, with mercurial days varying between 176 and 58.7 earthen days, as you can read up in Wikipedia [wikipedia.org]
You can't exactly put a base on the "unlit side", though. All sides get sunlight at some point. It's like saying that the humans have built Washington DC on the night-side of Earth: possibly technically true when said, but not very descriptive since that changes.
Those are just the approach images, the shots taken up through yesterday that show what the probe saw as it was speeding toward the planet. The close-ups taken today will be downloaded and posted over the coming hours and days. http://messenger.jhuapl.edu/gallery/sciencePhotos/ [jhuapl.edu]
Well, it'll go into orbit eventually, so yes. Hopefully.
And even without getting a lot closer, this is *huge*. Fully 55% of Mercury's surface has never been imaged by spacecraft (and cannot really be imaged well from the ground), so we don't have a very good idea what more than half the planet looks like. This flyby, I'm told, well see about half of the un-imaged area.
Hats off to the folks who put this together. I was in high school the last
time we saw any closeup pictures of Mercury. Every time we send probes to other
panets we find out really cool stuff. Messenger should be no exception.
If we can't go there ourselves, we can send robots. Robots are cool.:-)
>A few of the first pictures are now available, with many more to come in the next few days.
Actually, only a few approach images are available. The first images from the close approach will not be available until 01/05/08 when Messenger has finished data collection and points its antenna towards Earth and begins to transmit data. Can't wait for images of a very harsh environment.
How about Quindicembre? But Dicembre really ought to be Dodicembre anyway since it's the twelfth month not the tenth, but if Dicembre is the twelfth, then the fifteenth would be Tredicembre.
Either way it's not really so long to wait, since this would be the thirteenth month.:-)
Actually July and August were just renamed. July was Quintilis before being renamed in honour of Julius and August was Sextilis. The year used to start in March (Spring) so the month numbers were correct at one time.
*clearly* he meant 01/15/8000000000008 , which in in the Mecurian calendar means the first month, fifteenth day in the 8-Trillion-and-8th Mecurian solar rotation.
Plus, the Mercury citizens have learned to simply abbreviate as '08' on their paper calendars-- if you write all the zeros, the paper calendars usually catch fire before you are done-- so it's important to write quickly!
You must have read this highly informative site [ufos-aliens.co.uk] and applied your intensive research efforts directly to the debunking of this obviously fake planetary fly-by. My hat is off to you; job well done buddy...
Dang it all, even I can't keep from laughing at that page.
stare for a tenth of a second at the Sun through 8x binoculars. then you will have some idea why a camera that can image mercury's sunlit surface can't detect stars.
Section of Reworked Venera-13 Image
http://www.mentallandscape.com/V_DigitalImages.htm [mentallandscape.com]
Checkout the venus pics if you havent already from the link above.
Mercury surface pics would be cool.
Nonsense. It's part of a perfectly natural cycle the planet goes through and if you stop driving your SUV you might even make the planet COLDER than it should be. There is no global warming problem;)
200km! Wow, that's incredibly close to Mercury. For comparison's sake, geosynchronous orbit (where all our TV and most communication satellites live) are at 36,371 km from earth, 181 times as far as this probe went to mercury. Even the highest resolution earth imaging satellites we have orbit at around 500km.
While you can't scoop up the dirt, being that close for visuals has to be nearly as good as landing there...
Again? (Score:2)
Re:Again? (Score:4, Insightful)
Parent
Re:Again? (Score:5, Informative)
Part of the problem, too, is that it's really tricky to get to Mercury due to the amount of delta-v you need to shed Earth orbit, plus unlike Mars, Mercury has a negligible atmosphere which makes aerobraking useless. That's why they did three slingshot maneuvers to get there. The navigation team at JPL has really outdone themselves with this flight, and are to be commended.
It actually takes more delta-v to get to the sun than it takes to leave the solar system from here. This is why that whole "send dangerous waste to the sun" is a really bad idea. It takes a huge amount of fuel and if you miss, you've got a dangerous payload in a highly eccentric orbit that almost certainly crosses the Earth's. What could possibly go wrong? :-)
And maybe it's because I'm a space nerd, but I think MESSENGER is glamorous as hell.
Parent
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And a solution to send garbage safely would be to aim it a bit high or low (perpendicular to orbit of Earth). The slingshot would almost never send it back towar
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If you point it right at the Sun from ground perspective, it will just come back to circle the Earth unless propelled really hard. One needs to find a way to bleed sun-orbiting speed off of it. There's no free lunch.
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Solar sails do not use the solar wind (i.e. charged particles) for propulsion, but the light pressure (photons). Also, you can actually control the direction of the thrust gained from from the solar sail by changing the direction in which the photons are reflected (at the expense of absolu
Re:Again? (Score:5, Informative)
With regards to you second question, unless the highly inclined orbit was altered again at perigee and apogee with respect to the sun, your payload would return to the Earth's orbit.
Note: I am not a rocket scientist, at least not for a while, but I have done a bit of interplanetary stuff like this. All the numbers come from google. And it is entirely possible I'm quite mistaken, but I hope this was a bit helpful.
Parent
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Re:Again? (Score:4, Interesting)
Interestingly enough, the navigation of this flight was outsourced to Kintex [kinetx.com]. The mission itself is managed by APL... AFAIK, JPL wasn't particularly involved.
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Re:Cant wait (Score:5, Informative)
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Yeah, but the emo nights are the worst. Planets can be so bipolar!
Re:Cant wait (Score:5, Funny)
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Re:Cant wait (Score:5, Funny)
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Re:Cant wait (Score:5, Funny)
Or... a Predator! *ducks*
Parent
Re:Cant wait (Score:5, Funny)
Sorry.
Parent
Zoom? (Score:2)
Re:Zoom? (Score:5, Informative)
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Re:Zoom? (Score:4, Funny)
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Re:Zoom? (Score:5, Informative)
And even without getting a lot closer, this is *huge*. Fully 55% of Mercury's surface has never been imaged by spacecraft (and cannot really be imaged well from the ground), so we don't have a very good idea what more than half the planet looks like. This flyby, I'm told, well see about half of the un-imaged area.
Parent
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The Planet?
They just took a few shots of the moon if you ask me.
Re:Zoom? (Score:5, Funny)
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Three Cheers for NASA! (Score:5, Insightful)
Hats off to the folks who put this together. I was in high school the last time we saw any closeup pictures of Mercury. Every time we send probes to other panets we find out really cool stuff. Messenger should be no exception.
If we can't go there ourselves, we can send robots. Robots are cool. :-)
...laura
Re:Three Cheers for NASA! (Score:5, Funny)
cool stuff? Now come on, this is Mercury.
Parent
Re:Three Cheers for NASA! (Score:4, Funny)
Parent
Correction (Score:3, Informative)
>A few of the first pictures are now available, with many more to come in the next few days.
Actually, only a few approach images are available. The first images from the close approach will not be available until 01/05/08 when Messenger has finished data collection and points its antenna towards Earth and begins to transmit data. Can't wait for images of a very harsh environment.
Oops... (Score:5, Informative)
The first images from the close approach will not be available until 01/05/08
Parent
Re:Oops... (Score:4, Insightful)
In Quîndecimber?
14 months is a long time to wait.
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In Quîndecimber?
14 months is a long time to wait.
Either way it's not really so long to wait, since this would be the thirteenth month. :-)
Re:Oops... (Score:5, Interesting)
Parent
Re:Correction (Score:5, Insightful)
Could we please use unambiguous date formatting?
Something like YYYY-MM-DD?
I guess you actually meant 2008-01-15 with a typo.
Parent
Re:Correction (Score:5, Funny)
Plus, the Mercury citizens have learned to simply abbreviate as '08' on their paper calendars-- if you write all the zeros, the paper calendars usually catch fire before you are done-- so it's important to write quickly!
Parent
Re:Correction (Score:5, Insightful)
ISO 8601.
Additionally, I'm completely unaware of anyone or anyplace using
YYYY-DD-MM as a date format, and my googleing seems to confirm that.
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I know the following post was less vague as there aren't 15 months, but for clarity sake can we ask for ISO dates?
2008-01-05: No mistakes.
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Dang it all, even I can't keep from laughing at that page.
Re:Photos are FAKE (Score:4, Insightful)
Parent
great flyby animation (Score:5, Informative)
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It's a FAKE! (Score:5, Funny)
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Not only that, but if you look closely enough, you can see it's just one of the faked moon photos upside down! Definitely a hoax!
A good quick read (Score:4, Informative)
After they found the Face... (Score:2, Funny)
Re:After they found the Face... (Score:4, Funny)
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Global warming on Mercury (Score:5, Funny)
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Extremely Close (Score:4, Interesting)
While you can't scoop up the dirt, being that close for visuals has to be nearly as good as landing there...