Chandrayaan 1, India's First Lunar Probe Options

[John Moore]

So...presuming we're looking at a 'dead duck' at this stage of procedures, will we be seeing soon another impact on the Moon -- according to staff writers from this Moon Daily article?

John
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A Moon Site

[Guest_Zvezdichko_*]

http://www.novosti-kosmonavtiki.ru/content/news.shtml

According to Novosti Kosmonavtiki the spacecraft will remain in orbit until 2012.

[blairf]

From the DPS abstract on the M3 presentation scheduled for early October.

"Discovery of Volatiles across the Moon by the Moon Mineralogy Mapper (M3)

The data also allow fundamental absorptions due to OH/H2O that occur near 3000 nm to be evaluated and mapped. These latter results are unexpected and have important implications for lunar science and exploration."

http://www.abstractsonline.com/plan/ViewAb...79-e98c22643ad2


Hope someone has made sure that the Augustine commission know this is coming down the line...

[nprev]

Link inoperative.

[Bhas_From_India]

Reason for failure is officially out...

India's ambitious moon mission Chandrayaan-I lasted less than half its expected life span because of excessive heat, the Indian Space Research Organisation (ISRO) has admitted.

The ISRO scientists had miscalculated the temperature on moon's surface which led to faulty thermal protection. Chandrayaan's orbit had to be raised from its originally planned 100 km from the moon to 200 km because of this problem. ISRO had then claimed that it was being raised for a better view of the moon's surface.

Admitting the lapse, director of ISRO satellite centre Dr T.K. Alex, said, "We assumed that the temperature at 100 km above the moon's surface would be around 75 degree Celsius. However, it was more than 75 degrees and problems started to surface. We had to raise the orbit to 200 km."

http://indiatoday.intoday.in/index.php?opt...amp;issueid=122

[nprev]

I'm surprised that they apparently used an original model for the expected radiant energy flux instead of legacy data from previous manned & unmanned lunar flights. Maybe I'm wrong, but you'd think that such information would be readily available from several sources. Was this just an assumption that got "yeah, yeah'd" rather than reviewed & challenged?

[marsbug]

From the DPS abstract on the M3 presentation scheduled for early October.

"Discovery of Volatiles across the Moon by the Moon Mineralogy Mapper (M3)

The data also allow fundamental absorptions due to OH/H2O that occur near 3000 nm to be evaluated and mapped. These latter results are unexpected and have important implications for lunar science and exploration."

http://www.abstractsonline.com/plan/ViewAb...79-e98c22643ad2


Hope someone has made sure that the Augustine commission know this is coming down the line...

Myself I'm trying hard not to get too excited before the actual papers come out, as abstracts can be decieving, but it's taken an effort of will....

[mcaplinger]

I'm surprised that they apparently used an original model for the expected radiant energy flux instead of legacy data from previous manned & unmanned lunar flights.

It's hard to know exactly where they went wrong, but there haven't been a lot of low polar orbit missions (I can't think of any before the most recent batch, except for Lunar Prospector, which was a spinner so the thermal design was much simpler.) Also, it's more likely to be more a case of not modeling the specific spacecraft response correctly than not understanding the basic environment. Low polar lunar orbit is a very challenging set of cases; it can be both really hot and really cold on the same orbit, the sun direction varies over all angles during the mission, etc, etc.

[dvandorn]

I find it interesting that one of the Lunar Orbiters had a similar issue with overheating, and IIRC it wasn't the first LO to be flown. Again IIRC, ground controllers had to change the spacecraft state, opening or closing a thermal door to manage heat within the vehicle even though this had an effect on the usability of the camera system.

So, while I'm sure there is enough blame to go around in any situation like this, I think it's also important to note that the Big Boys, the people who did this kind of thing for the first time a couple of generations ago, ran into similar problems even after they thought they knew what the environment was like. So, cut the ISRO people a little slack... This is an excellent learning opportunity that will make their follow-on missions even better.

-the other Doug

[ilbasso]

What's inexcusable, in my book, is to find that there's an unanticipated heat problem, raise the orbit, and then tell the world that it was done for "a better view." You deprive the rest of the world of learning from your mission, condemning others to possibly making the same mistake. And for me, it would now make me more skeptical of any news released by the mission team - i.e., what are they leaving out that didn't fit their predictions or which failed to confirm their hypotheses? The whole thing starts to smack of being a propaganda tool rather than a scientific mission.

[ugordan]

What's inexcusable, in my book, is to find that there's an unanticipated heat problem, raise the orbit, and then tell the world that it was done for "a better view."

Am I imagining things or hasn't the real reason of the orbit raise been known for quite some time? Off-the record if not publicly?

[Guest_Zvezdichko_*]

I can't say it for sure. Look at the earlier report:

http://kuku.sawf.org/News/58147.aspx

It was said it was being done for science.

I'm confused.

[nprev]

Ilbasso has a point; there are two conflicting reasons given for the orbit raising, and that doesn't help the team's credibility. However, I'd be willing to bet that this turns out to be a function of several things: translation difficulties (not only linguistics, but also tech-to-layman communication in the Indian popular media), last-minute heroics to understand the problem & save the mission ("let's raise the orbit to cool it off, and maybe we'll also get lucky & get better data from a higher perspective!"), and of course fear ("if we screw this up, the papers will roast us & ISRO will suffer in the budget!")

All of the above should sound pretty familiar from the history of the early days of most nations' space programs.

[Bhas_From_India]

Failure of key unit could have led to Chandrayaan-1 end
....the second (redundant) bus management unit, which ISRO was using after the first one failed within a few weeks of the mission launched on October 22 last year, stopped functioning resulting in loss of contact with the spacecraft....
NOTE: No official confirmation.

Scientists review Chandrayaan failure
Asked about the ISRO’s admission that a “miscalculation of the moon’s temperature” led to the satellite’s abrupt end on August 29, ISRO Chairman G. Madhavan Nair said: “Unfortunately, the reflection from the moon was much larger than expected and higher than what the literature data indicated.”
http://beta.thehindu.com/news/national/article16626.ece

"Aditya-1 may help satellites dodge solar radiation"
http://beta.thehindu.com/sci-tech/science/article16623.ece
NOTE: Should this be moved to any other thread??

[ugordan]

ISRO Chairman G. Madhavan Nair said: “Unfortunately, the reflection from the moon was much larger than expected and higher than what the literature data indicated.”

And yet, according to an unsubstantiated report over at NSF.com, apparently American counterparts involved in the mission warned them about the thermal issue. Allegedly the Indians didn't listen to those warnings and Chandrayaan 1 flew insufficiently shielded.