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ICE is alive !
Hungry4info
post Oct 4 2008, 05:10 PM
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QUOTE (ugordan @ Oct 4 2008, 07:49 AM) *
Yes, but what's the harm in leaving the spacecraft alive?

Funding.


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ugordan
post Oct 4 2008, 05:12 PM
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QUOTE (Hungry4info @ Oct 4 2008, 07:10 PM) *
Funding.

Funding doesn't run the spacecraft radio transmitter. It does not do so whether we're listening or not.


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Hungry4info
post Oct 4 2008, 05:17 PM
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Oh. I thought one needed to continue funding a mission for it to remain active/operational, like with Voyager. Is the funding to pay the people who work with the spacecraft?


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scalbers
post Oct 4 2008, 05:40 PM
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QUOTE (tedstryk @ Oct 4 2008, 02:32 PM) *
I think you are thinking of Viking 1.

Thanks for the correction Ted. Here's more clarification from Wikipedia:

The Viking 1 Lander was named the Thomas Mutch Memorial Station in January 1982 in honor of the leader of the Viking imaging team. The lander operated for 2245 sols (about 2306 earth days or 6 years) until November 11, 1982, when a faulty command sent by ground control resulted in loss of contact. The command was intended to uplink new battery charging software to improve the lander's deteriorating battery capacity, but it inadvertently overwrote data used by the antenna pointing software. Attempts to contact the lander during the next four months, based on the presumed antenna position, were unsuccessful.


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brellis
post Oct 4 2008, 05:42 PM
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Polluting the solar system with radio waves could be a serious issue as we develop more sensitive instruments for listening to the cosmos.
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ugordan
post Oct 4 2008, 05:49 PM
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QUOTE (brellis @ Oct 4 2008, 07:42 PM) *
Polluting the solar system with radio waves could be a serious issue as we develop more sensitive instruments for listening to the cosmos.

I don't see how this can worsen the situation when we've already crowded the Earth orbit with all kinds of radio-active stuff. As along as it's tracked and catalogued, no confusion should arise. We might as well turn the Voyagers off then - or do missions that radiate, but continue to be funded not classify as "pollution"?


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dvandorn
post Oct 4 2008, 05:56 PM
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OK -- there are a few reasons why, at the end of a spacecraft's mission, you would want to shut it down and turn off its systems, including its radio transmitter/receiver.

It's true that funding only really pays for the ground support of a mission. Extended missions are funded to pay for the DSN time it takes to communicate with the spacecraft, and to pay the people tending the spacecraft, both in an engineering and in a scientific sense.

Turning off the spacecraft may just be a formality on a vehicle that is nearly out of RCS fuel, for example, or a vehicle that is about to go into a power-negative state for longer than it can ever be expected to recover from. Each of these things happens with fair frequency.

Another reason to turn off a spacecraft is to shut down any further requests for an extended mission. On a political level, someone in management somewhere may be sick to death of seeing extension after extension to a given mission drain funds off from projects that manager is more interested (or invested) in. A final directive to a final mission extension is often "shut down the spacecraft in such a way that it cannot be revived," or words to that effect. It's a way of stating with certainty that *no* further extensions will be allowed.

And, if you have no further interest in using the spacecraft, there is a legal principle that suggests you want to deny that resource to anyone who might want to use it for purposes of which our country may not approve. Now, I grant you, there is very little one could do with a 30-year-old probe that would violate America's interests... but, as with a lot of legal principles, it looks at low-likelihood events with very large consequences and decides what actual preventive measures are warranted. In some cases, you want to shut down your spacecraft at the end of their missions just to make sure no one else tries to use them.

-the other Doug


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ugordan
post Oct 4 2008, 06:15 PM
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QUOTE (dvandorn @ Oct 4 2008, 07:56 PM) *
A final directive to a final mission extension is often "shut down the spacecraft in such a way that it cannot be revived," or words to that effect. It's a way of stating with certainty that *no* further extensions will be allowed.

Given that reasoning and assuming the same was the case with ICE, if I were to be sarcastic I'd say the next command transmitted to ICE should then be "power down"... rolleyes.gif


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brellis
post Oct 4 2008, 10:56 PM
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QUOTE (ugordan @ Oct 4 2008, 10:49 AM) *
I don't see how this can worsen the situation when we've already crowded the Earth orbit with all kinds of radio-active stuff. As along as it's tracked and catalogued, no confusion should arise. We might as well turn the Voyagers off then - or do missions that radiate, but continue to be funded not classify as "pollution"?


The Voyagers are providing very valuable information, and they will continue to do so for decades to come, but one day they could be considered our first pieces of interstellar refuse. Near-earth debris is of much more concern!

On this topic, I raise the issue of radio pollution only as a possible reason why they wanted to turn it off in 1999. When we tried to contact it, it was right where we thought it would be, but what if it wasn't?

Location of the source could be a big issue. If post-mission ICE is in an earth-type orbit around the sun, still sending signals, but we can't control it, or can't locate it, then we have created a piece of interplanetary radio debris that follows us around, pointed at earth. While similar to no-longer-useful near-earth radio transmissions, we do have precise tracking of earth-orbiting radio satellites, both active and inactive. As we refine our space-based radio observations, we're getting more sensitive cosmic ears. A forgotten spacecraft floating in interplanetary space that should have had its transmitter turned off would create unnecessary work for a mission team.

It's a bit like the space debris problem -- if ICE were transmitting and nobody remembered leaving it on, it might create an unnecessary crisis.
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climber
post Oct 5 2008, 12:41 PM
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I guess dmuller would have to add ICE there: http://www.dmuller.net/space/


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Geert
post Oct 5 2008, 05:07 PM
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QUOTE (tasp @ Oct 4 2008, 08:00 PM) *
Has anyone looked over where ICE has been hanging out for the last 10 years?? Some seedy bar in the asteroid belt, or soaking up some rays around Venus ??


I seem to remember that calculations around the time of its end of mission already showed that it would return to the vicinity of earth somewhere around 2008-2009 and might even be captured once again into earth orbit (more or less similar to what happened to the Apollo 12 SIV-b stage). Did a quick check to find this source but couldn't find it so I might be wrong or mistake it with Giotto...
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Paolo
post Oct 5 2008, 07:05 PM
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Two extracts from "Robotic Exploration of the Solar System - vol 2"

On 5 May 1997 NASA terminated ICE operations and support, but the transmitter was purposefully left on in order to allow further tracking, as was done in 1999 when it traveled behind the Sun and the radio signal was used to probe the corona.

three options have been identified for further extending the ICE mission after its August 2014 lunar flyby, providing it is still working. The simplest option would be to return the spacecraft to its station in the L1 halo orbit, 32 years after it left it. Another option would be to place it into a highly elliptical Earth orbit whose apogee could be lowered by aerobraking passes through the upper atmosphere until it could be retrieved so that its coating of cometary material could be analyzed and the spacecraft finally donated to the Smithsonian National Air and Space Museum. Finally, ICE could be targeted to make a second flyby of Giacobini–Zinner on 19 September 2018. The original rationale for this option was that it would encounter Giacobini–Zinner a fortnight before NASA’s CONTOUR could do so if that mission were to be extended.
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dmuller
post Oct 5 2008, 07:07 PM
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QUOTE (climber @ Oct 5 2008, 10:41 PM) *
I guess dmuller would have to add ICE there: http://www.dmuller.net/space/

Yes I should update that part of my website, and not just for ISEE-3/ICE ... the days (here on Earth) are just too short


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Geert
post Oct 6 2008, 04:13 AM
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QUOTE (Paolo @ Oct 6 2008, 02:05 AM) *
Two extracts from "Robotic Exploration of the Solar System - vol 2"


I have already pre-ordered as soon as that was possible, vol 1 was very good and looking forward to vol 2, hopefully I receive my copy soon, off course you beat me to it ;-). But my memory was right then, the transmitter was purposefully left on and not accidentally forgotten or something.

QUOTE (Paolo @ Oct 6 2008, 02:05 AM) *
three options have been identified for further extending the ICE mission after its August 2014 lunar flyby, providing it is still working. The simplest option would be to return the spacecraft to its station in the L1 halo orbit, 32 years after it left it. Another option would be to place it into a highly elliptical Earth orbit whose apogee could be lowered by aerobraking passes through the upper atmosphere until it could be retrieved so that its coating of cometary material could be analyzed and the spacecraft finally donated to the Smithsonian National Air and Space Museum. Finally, ICE could be targeted to make a second flyby of Giacobini–Zinner on 19 September 2018. The original rationale for this option was that it would encounter Giacobini–Zinner a fortnight before NASA’s CONTOUR could do so if that mission were to be extended.


How about the engines and the fuel? I suppose all these options require some (minor) course corrections, would we still be able to successfully complete these? Returning it to earth would be the most spectacular however no chance to get a budget for this I suppose unless a really wealthy sponsor jumps in (Google?). Finding cometary material after aerobreaking? I doubt it. Returning it to its home base at L1 would be nice too, just for the fun of completing the 'roundtrip', and if we would be able to get its science payload back to life it might still be useful there.
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Weasle
post Nov 6 2008, 02:55 PM
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I registered on the forums to let you all know.

My girlfriends father actually worked on and was one of the main engineers for this satellite. NASA is very close by in Goddard. Anyway they brought him back on payroll recently and they turned the satellite back on.

If you all have any questions I am sure I can get them answered by talking with her dad. He lives right down the street and they are trying to get the satellite back to do more missions and then finally put it in the Smithsonian.
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