Jul 27 2015

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So where exactly is Philae?

The last post got me to wondering why we still don’t know where Philae actually ended up. Turns out, there is more data out there, just not in your normal space news sites. Bottom line, they still haven’t pin-pointed the exact location (you can bet that they would be announcing such a find with trumpets).

However…we can narrow it down a bit.

The first bit of news I found (from 15 June) was this:

They compared pictures from before the landing to after the landing — that bright spot that looks like a lander wasn’t there before (source: Has ESA Discovered Rosetta’s Philae Lander On Comet’s Surface?). But

  1. they’re not sure if that’s Philae or just a bright rock outcrop that has been exposed as Chury vents off gas, and
  2. They don’t tell where in blazes this picture is actually located on the comet…how maddening!!!

But that tells me that the lander likely isn’t where they thought it landed. Then I found this from phys.org (14 April) :

which was reporting that they were able to determine that Chury’s core is not magnetized because of data collected from Philae’s multi-bounce landing.

Then, by sensing periodic variations in the measured external magnetic field and motions in its boom arm, ROMAP was able to detect the touchdown events and determine the orientation of Philae over the following hours. Combined with information from the CONSERT experiment that provided an estimate of the final landing site location, timing information, images from Rosetta’s OSIRIS camera, assumptions about the gravity of the comet, and measurements of its shape, it was possible to determine Philae’s trajectory.

The mission teams soon discovered that Philae not only touched down once at Agilkia, but also came into contact with the comet’s surface four times in fact – including a grazing collision with a surface feature that sent it tumbling towards the final touchdown point at Abydos.

Well, now it’s clear that the brainiacs at ESA were completely wrong about their initial guess as to where Philae landed. I wasn’t correct either, but I was MUCH, MUCH closer, particularly in terms of distance. I predicted that Philae landed about 1535 meters from the original landing spot, as compared to the 500 meter guess of ESA. As you can see, Philae traveled about 1250 meters from its initial landing spot.

I’m doing the “I’m right” happy-dance on the distance because when I made my prediction, it had not been reported that Philae touched down multiple times, just that it took a couple of hours for it to come to rest. With each bounce, it would lose some momentum — if it had taken less bounces, the final distance would have been even closer to what I predicted.

Not bad for a back of the envelope calculation with only a rough guess as to the gravity constant on Chury, right?

However, as far as vector, I was a little bit off. It looks like Philae bounced about 10 degrees more toward the west than I originally calculated (still, not bad for just using Paint.net to compare images), but then I didn’t anticipate Philae veering almost due West after it’s first bounce.

Still, my final prediction was that Philae was down in the “neck” of Chury buried in shadows most of the time, and that’s where it looks like it ended up.

Not, mind you, still on the “head” basking in sunlight like ESA originally predicted.

Again I say when it comes to all things Philae: MAN I’m good!

Just sayin’…

Permanent link to this article: http://www.newspaceraces.com/2015/07/27/so-where-exactly-is-philae/

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