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MESSENGER News Thread, news, updates and discussion
tasp
post Nov 30 2005, 06:02 PM
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QUOTE (JRehling @ Nov 30 2005, 10:37 AM)
The main thruster is apparently "this". It will be fired for the first time in this manuever. If "this"  tongue.gif  works, then we can have high expectations of a successful mission.

For no particular timely reason, I will re-voice the angst that it is so long between launch and any interesting science (even a Venus flyby)... If the earlier launch window had been hit, the mission would have been accelerated by *years*. The launch window that was used seems to have been about the worst one possible in terms of cruise duration.
*



Has anyone looked at return paths from Mercury to earth via Mercury, Venus and earth gravitational assists?
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JRehling
post Nov 30 2005, 07:53 PM
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QUOTE (tasp @ Nov 30 2005, 10:02 AM)
Has anyone looked at return paths from Mercury to earth via Mercury, Venus and earth gravitational assists?
*


It should be roughly symmetrical. You can't make the planets reverse direction, but conceptually...

The big problem is that a trip to Mercury starts with a huge rocket on the surface of the Earth. Getting a big rocket to the surface of Mercury is going to be a problem. The requirement would be at least to reach Mercury escape velocity and then enter a minimum-energy transfer orbit from Mercury's aphelion to Venus. Some additional savings could be had by using Mercury flybys to pump the orbit out to Venus. The rocket capable of that operation has to be the *payload* of some other rocket. The demands are incredible, certainly beyond any unmanned mission ever flown.

There would be an energy savings if, like Apollo, a remote rendezvous took place, so that the return fuel for the interplanetary cruise did not have to be landed onto the surface of Mercury. This would help, but the demands would still be huge (a rocket that could perform the cruise would have to enter Mercury orbit no matter how you look at it).

Look, it's just not going to happen in our lifetime! wink.gif
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dvandorn
post Nov 30 2005, 10:41 PM
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Well, it *may* not happen in the lifetimes of the average members of this forum. But that all depends on the state of advancement of propulsion technology. I've seen some articles on plasma drive concepts that are being championed by, among others, Franklin Chang-Diaz, that could dramatically increase the amount of delta-V capacity a spaceship can drag along with it.

If we can develop bigger, better propulsion systems in the next 20 or 30 years, things that can give you constant acceleration for most of your flight (and not at measely 1/100th G levels, either), then you can tool around the Solar System in months when you used to need to spend years. Months or years when you used to need decades.

It's not like we will *always* be limited to push-real-hard-then-coast-for-years technologies. At least, I'm sincerely hoping not.

-the other Doug


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tasp
post Dec 1 2005, 02:42 AM
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I was hoping that since Messenger was launched on a mid size rocket, and that a large part of the delta vee is from the grav. assists at earth Venus, and Mercury, a big Titan IV (or whatever the big launcher is now) could send a useful vehicle on a two way trip. The 'smash and grab' idea for a sample return I saw here is just starting to seem a little more doable, perhaps . . . .

Amazing to be looking at these (formerly) exotic trajectories, from Mercury sample returns to Pluto landers, it just keeps getting better all the time.
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Guest_BruceMoomaw_*
post Dec 1 2005, 10:22 PM
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Actually, it might be doable with a smaller booster. The question is how fast a flyby speed at Mercury you're willing to put up with during the sampling. Messenger will make multiple gravity-assist flybys of Mercury to slow itself down in order to minimize the fuel it has to burn at Mercury Orbit Insertion, but that problem doesn't apply to a nonstop smash-and-grab sampling flyby. The question is the speed at which the collected particles can plow through the aerogel before the frictional heat ruins them for scientific analysis.

But if you are willing to make that sampling run during your first flyby of Mercury, then making your way back to Earth via Venus gravity-asssist flybys becomes much easier and shorter.
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Guest_BruceMoomaw_*
post Dec 12 2005, 09:21 PM
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http://www.space.com/astronotes/astronotes.html : Messenger fired its big engine successfully for almost 9 minutes on Dec. 12 -- the last component of the craft that hadn't been operated until then. So everything works (except for occasional software collywobbles). Now if everything will just continue working...
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ljk4-1
post Dec 14 2005, 07:45 PM
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A thought from someone on another space list:

Will MESSENGER and Venus Express conduct any joint studies on Venus like Galileo and Cassini did with Jupiter in 2000? And if they can and do, what could they do together that they could not do alone?


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Guest_AlexBlackwell_*
post Dec 14 2005, 08:28 PM
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It might be possible during the June 2007 flyby; however, MESSENGER won't be collecting science data during the October 2006 flyby (due to solar conjunction), so that opportunity is out.
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Guest_AlexBlackwell_*
post Feb 23 2006, 05:35 PM
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MESSENGER Mission News
February 23, 2006
http://messenger.jhuapl.edu/

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MESSENGER Lines Up for Venus Flyby

MESSENGER trajectory correction maneuver 10 (TCM 10) lasted just over two minutes and adjusted its velocity by about 1.4 meters per second (4.6 feet per second). The short-duration maneuver yesterday placed the spacecraft on track for its next major mission event: the first Venus flyby on October 24, 2006.

Having completed six successful small TCMs that utilized all 17 of the spacecraft’s thrusters, this latest maneuver was the first to rely on the four B-side thrusters. During this maneuver, the thrusters on the opposite side of the spacecraft reduced a build-up of angular momentum due to an unseen force that causes the spacecraft to rotate if left uncorrected. This maneuver was only the seventh actual TCM for MESSENGER; the spacecraft’s trajectory was so close to optimal after TCM 3 and TCM 6 that planned TCMs 4, 7 and 8 weren't necessary.)

The maneuver started at 11 a.m. EST; mission controllers at The Johns Hopkins University Applied Physics Laboratory (APL) in Laurel, Maryland, verified the start of the maneuver within 11 minutes and 48 seconds, when the first signals indicating spacecraft thruster activity reached NASA's Deep Space Network tracking station outside Goldstone, Calif.

At the start of the maneuver, the spacecraft was 132 million miles (212 million kilometers) from Earth and 83 million miles (133 million kilometers) from the Sun, speeding around the Sun at 68,163 miles (109,698 kilometers) per hour.

For graphics of MESSENGER's orientation during the maneuver, visit the “Trajectory Correction Maneuvers” section at http://messenger.jhuapl.edu/the_mission/mission_design.html.


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Earth Flyby Image Gallery Now Online

MESSENGER’s Mercury Dual Imaging System (MDIS) acquired spectacular images during the Earth flyby in August 2005, including a "film" of our home planet as it receded in the distance. Now, you can browse through the best of the MDIS flyby frames on the MESSENGER Web site!

Visit the MDIS Earth Flyby gallery at http://cps.earth.northwestern.edu/MESSENGER_20050802/.
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dilo
post Mar 22 2006, 08:52 PM
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Flyby images are beautiful, thanks Alex.
Starting from one eof these pictures and using also the famous MRO moon image, I made these mosaics... is only a "petit divertissment", first one should be geometrically more correct, while second one is a tribute... wink.gif
Attached Image
Attached Image


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angel1801
post Mar 23 2006, 11:10 AM
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QUOTE (AlexBlackwell @ Dec 15 2005, 05:58 AM) *
It might be possible during the June 2007 flyby; however, MESSENGER won't be collecting science data during the October 2006 flyby (due to solar conjunction), so that opportunity is out.


This is because Mercury transits the Sun on November 8 (19:14 UT) to November 9 (00:15 UT). And transits can only occur at inferior conjunction ie when Mercury anf Earth line up in a straight line anf Mercury is at "New moon" phase. Mercury is too close to the Earth for a month or so before and after the inferior conjunction for realiable transmission of data.


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Guest_AlexBlackwell_*
post Mar 23 2006, 04:48 PM
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QUOTE (angel1801 @ Mar 23 2006, 11:10 AM) *
This is because Mercury transits the Sun on November 8 (19:14 UT) to November 9 (00:15 UT). And transits can only occur at inferior conjunction ie when Mercury anf Earth line up in a straight line anf Mercury is at "New moon" phase.

Thanks, angel1801. I think I remember something like that from an Astronomy 101 lecture but my memory is hazy because I was at a frat party the night before.

QUOTE (angel1801 @ Mar 23 2006, 11:10 AM) *
Mercury is too close to the Earth for a month or so before and after the inferior conjunction for realiable transmission of data.

Comm hiatus for solar conjunctions is a feature of many interplanetary missions. And I think you meant to write "Mercury is too close to the Sun..."
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ugordan
post Mar 23 2006, 05:06 PM
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QUOTE (AlexBlackwell @ Mar 23 2006, 05:48 PM) *
Comm hiatus for solar conjunctions is a feature of many interplanetary missions. And I think you meant to write "Mercury is too close to the Sun..."

I'm lost. Isn't the next flyby that's not going to be taking any science a Venus flyby? If so, what's Mercury got with it?

I'm also a bit puzzled by this no-science policy. Why couldn't have they programmed the s/c to play the data back a couple of days/weeks later?


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Guest_Sunspot_*
post Mar 23 2006, 05:11 PM
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QUOTE (ugordan @ Mar 23 2006, 05:06 PM) *
I'm also a bit puzzled by this no-science policy. Why couldn't have they programmed the s/c to play the data back a couple of days/weeks later?


That's what I was thinking too......
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Guest_AlexBlackwell_*
post Mar 23 2006, 05:16 PM
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QUOTE (ugordan @ Mar 23 2006, 05:06 PM) *
I'm lost.

Take a number, ugordan. I was "lost" first. tongue.gif

QUOTE (ugordan @ Mar 23 2006, 05:06 PM) *
Isn't the next flyby that's not going to be taking any science a Venus flyby? If so, what's Mercury got with it?

Assuming angel1801 was referring to the upcoming Venus flyby, you're right, though rather than issuing two corrections, I gave him/her the benefit of the doubt and assumed he/she was making a general statement with respect to MESSENGER being in orbit around Mercury. That's my "Bruce excuse." In reality, I just wasn't paying too close attention. biggrin.gif

This post has been edited by AlexBlackwell: Mar 23 2006, 05:17 PM
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