Earth Departure Movie From MESSENGER Spacecraft

A reader writes:"The Mercury-bound MESSENGER spacecraft took 358 images during a gravity assist swingby of Earth on Aug. 2, 2005. Those images were sequenced into an MPEG movie showing the view from MESSENGER as it departed Earth."

Comments

Impressive!

[Henriok]

This is the real deal! The Earth is getting smaller in a realistic manner witch I've never seen before. I wonder what kind of acceleration and speed we are taling about here? These would be completely different figures in the movie and the real event. Someone care to do the math?

Don't you just love the reflection of the Sun? And the absence of a "glowing" atmosphere halo? This is what the Earth really look like. Please render planets like this when you do SciFi flicks in the future!

Underwhelmed

[Linker3000]

With the current state of CGI and a world awash with 'fake' scifi images running all the way back to 2001: A space Odyssey, it's a shame that this footage just looks so 'plain' even though it's 'the real thing'. Mind you, I find Google Earth truly fascinating.

collision 27th frame from end

[emptybody]

go frame by frame for some interesting events.
most spectacular is the flash 27 frames from the end. looks like it could be lightning or a large meteor.

Re:collision 27th frame from end

[Ariane 6]

Well, if we saw a thin crescent Earth, then the solar phase angle (sun-earth-observer) would be nearly 180 degrees, and the specular highlight would be right on the western (left) horizon, just like you see on when watching sunset over the ocean on Earth's surface. Since we're seeing a less mature crescent, that means that the angle is in fact only slightly greater than 90, and the highlight hasn't gone that far yet.

Phase = 0 --> highlight is directly below you

Phase = 90 --> highlight is halfway between nadir and the western limb

As phase tends to180 --> highlight disappears over the western limb.

Looks like that Orbiter simulator

[flinxmeister]

Has anyone played with that Orbetor Simulator?

Seeing this animation made me realize just how good that programmer is. The visualizations on that simulator nailed it pretty well. And it's free too!

Question!

[nherm]

Ok I got a question about the spacecraft's orbit!

From the video, the spacecraft seems to be travelling at the opposite direction of earth's translation (i.e. clockwise in the ecliptic plane, viewing from sun's north to south hemisphere), because the dayside is at the left, and the Earth is, well, becoming smaller...

But, this diagram of messenger's orbit from the article in wikipedia shows that the spacecraft travells in the counter-clockwise direction (same as the planets)... so, I would conclude that the spacecraft speed is less than the Earth's orbital speed.

Question: is that correct?

Re:Question!

[jrboatright]

Orbital mechanics is "not obvious."

as an object drops into a lower orbit they orbit in fewer seconds. Venus goes around the sun in fewer days than earth does, as does mercury...

HOWEVER, the linear velocity of an inner orbit is slower than the linear velocity of an outer orbit.

So, to go in, you slow down. Which results in dropping to a lower orbit, which results in your pulling out "in front" of the object you're seperating from leaving it both "above" you and "behind" you.

So, accelerating spinwise is out, and slower.

Accelerating anti-spinwise is in, and faster

let us not get into what happens when you accelerate OUT or IN....

Re:Interesting

[alfboggis]

Yeah, the earth is actually pretty smooth. Its diameter is 13,000 km, while Mount Everest is only about 9km high -- just 0.07%. Clouds cling very close to the surface at about 5km. That's about the thickness of a piece of paper compared to a basket ball.