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General Astronomy >> General Observing and Astronomy

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CharlesW
scholastic sledgehammer


Reged: 11/02/12

Loc: Chula Vista & Indio, CA
End of mission for LADEE new
      #6081232 - 09/14/13 10:38 PM

I read that LADEE has a six month mission life. Any chance they will bury the spacecraft into a convienently located mountainside that will be visible to us at EOS.

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mjs
sage


Reged: 02/26/04

Loc: Northern Indiana
Re: End of mission for LADEE new [Re: CharlesW]
      #6082253 - 09/15/13 03:12 PM

They're going to crash it into the Moon's surface at the end of the mission but I don't know where and doubt that it would be visible to backyard telescopes. LADEE isn't very large.

Mike


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brianb11213
Postmaster
*****

Reged: 02/25/09

Loc: 55.215N 6.554W
Re: End of mission for LADEE new [Re: mjs]
      #6082301 - 09/15/13 03:44 PM

Sheesh, the thing hasn't even started operating yet & you're already looking forward to termination?

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CharlesW
scholastic sledgehammer


Reged: 11/02/12

Loc: Chula Vista & Indio, CA
Re: End of mission for LADEE new [Re: brianb11213]
      #6082779 - 09/15/13 08:36 PM

I appreciate that the satellite isn't large at all, but the impact dust cloud could be. And I really can't get excited about what I would call a self-made employment opportunity for a number of atmospheric scientists and engineers. Looking for an atmosphere that is so sparse its atoms don't even collide? I'm as big a science fan as the next guy but come on.

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bluesteel
sage


Reged: 03/24/13

Loc: ILM
Re: End of mission for LADEE new [Re: CharlesW]
      #6083098 - 09/16/13 12:46 AM

Didn't lcross already send a kinetic bomb impacting the moon? And did it not ring like a bell for several minutes? Sounds like a waste of a perfectly good spacecraft, or an ulterior motive to me... And that kinetic bomb was over 2 tones of TNT equivalent from lcross... Don't think that satellite could even begin to match that... Kinetically.

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David Knisely
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Reged: 04/19/04

Loc: southeastern Nebraska
Re: End of mission for LADEE new [Re: CharlesW]
      #6083141 - 09/16/13 01:27 AM

Quote:

I appreciate that the satellite isn't large at all, but the impact dust cloud could be. And I really can't get excited about what I would call a self-made employment opportunity for a number of atmospheric scientists and engineers. Looking for an atmosphere that is so sparse its atoms don't even collide? I'm as big a science fan as the next guy but come on.




I remember watching the moon as Apollo 13's third stage S-IVB hit the moon. We didn't see anything despite the fact that the stage weighed-in at a whopping 22,599 lbs and hit the moon going about 5,572 mph. It only made a crater about 135 ft across and the ray pattern only went out to around 150 meters (492 ft) or so from the crater rim, so such an impact was a very brief event and probably not detectable from here on Earth.

As why LADEE is being flown, it is to find out more about the lunar atmosphere, as there are still quite a number of things we don't know about it. Another reason to do this mission is the presence of elevated dust just above the lunar surface. There is a real possibility that fine lunar dust being elevated and later settling on equipment might cause some problems when we eventually get around to sending long-term missions back to the moon. It is best to find out whether there may be a problem or not, as some observations during the Apollo missions indicated that something odd might be going on when it comes to the elevated lunar dust in the very very fine lunar atmosphere. LADEE may help answer this question. As for when and why it is probably going to be targeted for an impact, lunar orbits are not stable long-term anyway, so the LADEE spacecraft will eventually hit the moon anyway once it runs out of fuel. It would be best to target that impact into an area that might have some possible sub-surface material or volatiles that might be detected later-on. Otherwise, it will just be allowed to hit the moon, although again for impact studies, it might be nice to know exactly where it hit so the area can be imaged. Clear skies to you.


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csrlice12
Postmaster
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Reged: 05/22/12

Loc: Denver, CO
Re: End of mission for LADEE [Re: David Knisely]
      #6083391 - 09/16/13 08:21 AM

The moon inhabitants will collect the wrecked craft and put it into Crater 51 where it will be studied. Rumour has it they have a couple of missing astronaut bodies in cold storage........

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bluesteel
sage


Reged: 03/24/13

Loc: ILM
Re: End of mission for LADEE new [Re: csrlice12]
      #6084034 - 09/16/13 02:17 PM

Quote:

The moon inhabitants will collect the wrecked craft and put it into Crater 51 where it will be studied. Rumour has it they have a couple of missing astronaut bodies in cold storage........



Crater 51 is old news. They now use crater fifty seven and eight tenths for storage now. They also like their astronauts how they like their coffee... Ground up and frozen.

Quote:

As for when and why it is probably going to be targeted for an impact, lunar orbits are not stable long-term anyway, so the LADEE spacecraft will eventually hit the moon anyway once it runs out of fuel.



Learn something new everyday! Those pesky mascons! Interesting though that they have found several areas where you can do a low orbit of sorts without decay. Why would NASA not want to park LADEE there for prolonged observation? Disposable satellites, like cell phones in this day and age? Clogging of instruments due to the dust they are trying to observe and analyze? It just seems so wasteful in my eyes to throw away the satellite without prolonged use... I'm looking at you as an example Voyager 1!


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csrlice12
Postmaster
*****

Reged: 05/22/12

Loc: Denver, CO
Re: End of mission for LADEE new [Re: bluesteel]
      #6084095 - 09/16/13 02:54 PM

But it's such fun blowing things up.........

But hey, what we gonna do when we find out that ain't no moon.........


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Tori
sage


Reged: 01/10/12

Loc: Somerville, MA/Warren, NH
Re: End of mission for LADEE new [Re: csrlice12]
      #6084397 - 09/16/13 05:43 PM

Quote:

The moon inhabitants will collect the wrecked craft and put it into Crater 51 where it will be studied. Rumour has it they have a couple of missing astronaut bodies in cold storage........




*chuckle*

Posts like this make me wish that cloudynights had a +1 or like button.


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Pinbout
Postmaster
*****

Reged: 02/22/10

Loc: nj
Re: End of mission for LADEE new [Re: Tori]
      #6084533 - 09/16/13 07:07 PM



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David Knisely
Postmaster
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Reged: 04/19/04

Loc: southeastern Nebraska
Re: End of mission for LADEE new [Re: bluesteel]
      #6085207 - 09/17/13 02:10 AM

bluesteel posted:

Quote:

Learn something new everyday! Those pesky mascons! Interesting though that they have found several areas where you can do a low orbit of sorts without decay. Why would NASA not want to park LADEE there for prolonged observation? Disposable satellites, like cell phones in this day and age? Clogging of instruments due to the dust they are trying to observe and analyze? It just seems so wasteful in my eyes to throw away the satellite without prolonged use... I'm looking at you as an example Voyager 1!




The orbit LADEE uses is one that requires a minimum of launcher energy to achieve (i.e. a small rocket like the Minotaur V). It is an orbit that ends up having both a low lunar altitude (20 to 60 km) and a low inclination. It also isn't just the mascons that are the problem. With a lunar orbit, you have three bodies involved: the moon (with its lumpy gravitational field), the Earth (the major "perturber"), and the Sun. It isn't so much a "decay" of the orbit as it is a perturbation in the orbit. Each body will introduce gravitational perturbations in the orbit that can be enough to slowly change that orbit, often eventually to a point where one part of it may intersect the moon's surface at some location. For all low lunar orbits (like the ones necessary for study of a weak lunar atmosphere), this can be unavoidable unless you do periodic thruster firings to re-establish the proper orbit (or use a very special inclination orbit at a bit higher altitude which minimizes the perturbations). Once you run out of fuel in your probe, it's usually "bye bye spacecraft". Orbits that are much higher than 750 km in altitude over the moon can even be perturbed into either escaping the moon altogether or smashing into the moon, although there are a few special case ones that can be stable for a much longer period of time (more useful as communication satellite orbits for farside lunar bases than for low-altitude lunar atmosphere studies).

Quote:

Clogging of instruments due to the dust they are trying to observe and analyze? It just seems so wasteful in my eyes to throw away the satellite without prolonged use




They aren't going to "clog" the instruments, as previous orbiting spacecraft haven't had that trouble. They are going to look for and study any dust which might be present not far above the lunar surface. The satellite should easily be able to gather its information in the time allotted before its fuel supply is exhausted. You can't "refuel" it. It would also have taken a bigger launcher and more fuel to get the spacecraft into one of those "frozen" stable lunar orbits, but those orbits may be too high to study what they sent LADEE there to look at. Nothing is being "wasted". It is as simple as that. Clear skies to you.


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