Chandrayaan images of Apollo

[smartcooky]

This is what makes the study of the actual physical universe so rewarding.  The truth is far more fascinating and far stranger than anything Adrian AwE130 or Neil Burns could possibly imagine.

Oooh, nice Mark Twain paraphrase there Jay!!

[JayUtah]

I did what?

[smartcooky]

I did what?

“Truth is stranger than fiction, but it is because Fiction is obliged to stick to possibilities; Truth isn't.”

― Mark Twain


Given all the references to certain "works of fiction", lately, especially as regards ghosts and golf courses, I thought it was rather apt.

[Sus_pilot]

I thought nutation is what happens to you when you go through the Van Allen belt.

[Runs towards exit as Jay flings coffee cup...]

[JayUtah]

That's a great Twain quote, one I've not heard before.  I grew up in the Midwest and it was all about Twain, but I guess there's always more Twain in heaven and Earth than is dreamt of in my philosophy.  Neil Burns would do well to take a cue from Mr Clemens.  There's a guy who both (a) knew how to make stuff up properly, and (b) knew how to make it entertaining.

Back to the subject at hand, these days I open with the notion that nutation is the process used to make Nutella.  But indeed, over in the programming-language topic I discussed programming ephemerides in Fortran, having to take into account both precessing and nutation.  Precession is significant only for astronomically large (no pun intended) time intervals.  But for accurate results over even small time periods you must account for nutation in Earth's dynamics so as to compute the location of objects in the sky accurately to with a second of their true location.

My coffee mug was a gift from the crew of one of the Cirque du Soleil shows in Las Vegas, so it has about as much chance of being thrown as a does a piece of flown space hardware.

[grmcdorman]

I thought nutation is what happens to you when you go through the Van Allen belt.

[Runs towards exit as Jay flings coffee cup...]

I thought it was the Van Halen belt?

:follows Sus_pilot at speed:

[AstroBrant]

This is what makes the study of the actual physical universe so rewarding.  The truth is far more fascinating and far stranger than anything Adrian AwE130 or Neil Burns could possibly imagine.

Oooh, nice Mark Twain paraphrase there Jay!!

Did you mean Shakespeare? "There are more things in Heaven and Earth, Horatio, than are dreamt of in your philosophy."
Oh, how correct he was!

Edit: Oh, now I see what you were referring to. Still, it was a good paraphrase of Shakespeare, too.

[AstroBrant]

If you lived on a lunar surface base, the Earth would stay in roughly the same place in the sky but would describe a figure-eight motion around a fixed point due to lunar libration. 

Hmm, I've always perceived that in an intuitive, careless way. I thought it would appear to move in a small circle. Now that I think about it more analytically, I still come up with a circle.

Edit: Maybe you're thinking of the sun's analemma.

[ka9q]

Precession is significant only for astronomically large (no pun intended) time intervals.

The earth's axis precesses once in about 26,000 years but it is significant enough over a human lifetime that positions of astronomical objects are referred to an epoch, usually 1950.0 or 2000.0.

Also, precession is very significant in the orbits of earth satellites, caused mainly by the earth's equatorial bulge. One orbit in particular, the sun-synchronous orbit, exploits precession in an interesting way. The satellite is launched into a circular, retrograde (east->west) orbit with an inclination and period carefully chosen so that the orbital plane precesses eastward 360/365.25 degrees per day. This causes it to exactly match the earth's orbital motion around the sun so that the orbital plane keeps the same relationship to the sun-earth line. The satellite thus passes over any given point on the earth's surface at the same local time each day and night, e.g., 3AM/3PM or 9AM/9PM.

[onebigmonkey]

So i was looking at Apollo 17's landing and take off 16mm footage and matching with LRO images, because that's what you do on a Sunday and I spotted something.

Below are 3 views of the same scene - on the left is the landing, centre is the LRO view, and on the right is the ascent video view.

What I'm interested in is the white object I've circled that is not present in the descent video (at least in the versions I've seen), but is there in the LRO and ascent.

Annoyingly, the first few seconds of Apollo 17's ascent wasn't captured, so we can't see if anything flew there and landed as a result of the ascent engine exhaust. Careful viewing of the footage that is available shows that the object seems to emerge and 'twinkle' in a way that brightly lit rocks in the scene don't. Annoyingly, the TV view from the rover is in exactly the wrong place and there is nothing obvious in the post-EVA views from the LM.

So - any thoughts?



Apart from aliens, carelessly discarded lighting rigs etc etc


(e2a: I've stretched and rotated the 16mm views to match the LRO view, in case anyone thinks they look different)

[Allan F]

How far from the landing site? Could be a piece of kapton.

[onebigmonkey]

How far from the landing site? Could be a piece of kapton.

About 25-30 metres. I wondered if it might be foil, but was surprised it wasn't still moving horizontally as it does in other ascent videos. A piece from Apollo 15 was visible moving for quite some distance in that ascent 16mm footage. I managed to track it down, as did someone else.

[Allan F]

If it was along the ascent trajectory, the exhaust would start to point away from it pretty quickly because of the pitchover maneuver which started the horizontal velocity increase.