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all 26 comments

[–]Hoyerman68 1 point2 points  (1 child)

Fantastic shot! Obviously a lot of planning went into the positioning/framing of the image. I terms of the exposure, what were the camera/lens used and exposure settings and did you use any kind of ND filter to get this exposure length? Also - is this a shot you’ve tried before at previous launches?

[–]jardeon[S] 0 points1 point  (0 children)

The photo was taken by a friend and colleague of mine, but I can answer most of your questions, as he gave me the details when he sent me the file to post.

The camera and lens were a Canon 7Dmk2, and a 10mm wide angle. The exposure was ISO100, f/18 and 472 seconds. No ND filter was needed, at night, an 8 minute exposure at f/18 would be almost completely blacked out, so the rocket and any directly visible light source (such as the lights along the shore) would be the only things that show up.

Mike has shot a Falcon 9 launch and landing from this location three times: Orbcomm OG2-M2 in 2015 (two photo composite); SpaceX CRS-9 in 2016 (single frame 483 second exposure) and the above photo from 2018.

[–]NuncErgoFacite 0 points1 point  (1 child)

So... if i understand this correctly, the camera shutter was open long enough for the booster rockets to complete a full orbit and land? I didn't realize the program used the same location to land as to launch. Wow.

[–]jardeon[S] 1 point2 points  (0 children)

The first stage booster doesn't perform a full orbit; the second stage and payload separate from it after 2.5 minutes. The first stage boosts back to an altitude of 250km, and lands back at the launch site (well, a few miles down the road on the same property) about 8 minutes after liftoff.

[–]unwilling_redditor 0 points1 point  (2 children)

I see the first stage ascent, second stage burn, first stage reentry, and first stage landing burn...

Where is the boost back burn?

[–]jardeon[S] 1 point2 points  (1 child)

If you zoom in on the second stage burn, the arc continues downrange to the right, the boostback is the "hook" shape lifting upwards and left from the second stage.

[–]unwilling_redditor 0 points1 point  (0 children)

Huh. I wouldn't have expected it to be that dim. Thanks.

[–]That_Film_Guy 1 point2 points  (3 children)

Where did you see this was a 472 second exposure?

[–]jardeon[S] 2 points3 points  (2 children)

Mike and I work together at We Report Space; when he sent me the photo, he also sent me exposure details.

[–]TravisPM 0 points1 point  (1 child)

Maybe there was a miscommunication but those clouds and star trails look more like a 30 sec to 1 minute exposure. Are you sure it's not a composite?

[–]jardeon[S] 0 points1 point  (0 children)

Definitely not a composite. Star trails appear shorter the closer to the North Star they are; from this vantage point, the shot is aimed almost due North.

[–]0hmyscience 12 points13 points  (14 children)

So what's going on here?

  1. The arch on the left, I assume, is the rocket launching.
  2. Where the arch ends, it turns blue, goes off, but them it seems to briefly re-ignite on the opposite direction? Is that right?
  3. The bottom "pillar", I assume that's the rocket landing. But which part is this? The other vertical "pillar" up in the air, or the same part from the arch?
  4. Where did the "pillar" on the top come from? Also, is it going upwards or downwards?
  5. I see other small horizontal-ish lines there... are those just star trails?

[–]AskMeForADadJoke 4 points5 points  (7 children)

Heres an animation of how it all works.

Its not the exact rocket (this one has two first stages) but the idea is there.

And here is the actual launch/landing

[–]shakexjake 0 points1 point  (4 children)

Asking here because I'm not sure who else to ask: What was slowing down Stage 1 between the entry and landing burns? Did it really slow down about 2k kph just from air resistance?

I'd also like to ask you for a dad joke.

[–]quarkman 1 point2 points  (0 children)

Yes, the 2k kph slowdown is entirely air resistance. Terminal velocity is only around 500kph max, so that's quite a bit slower than the 3k kph it was starting out after the initial reentry burn.

Note that they initially didn't have the first reentry burn and the rocket came in too hot.

[–]AskMeForADadJoke 1 point2 points  (2 children)

Asking here because I'm not sure who else to ask: What was slowing down Stage 1 between the entry and landing burns? Did it really slow down about 2k kph just from air resistance?

No idea. I would think so, but I have zero credentials to answer.

I'd also like to ask you for a dad joke.

Why was the poor man selling yeast?

He kneaded to raise some dough.

[–]shakexjake 1 point2 points  (1 child)

Thank you for answering both of my requests!

[–]AskMeForADadJoke 0 points1 point  (0 children)

Of course :)

I would ask r/spacex or r/askscience

[–]codeByNumber 1 point2 points  (1 child)

It’s honestly still just mind blowing to me.

[–]AskMeForADadJoke 0 points1 point  (0 children)

Completely agree

[–]jardeon[S] 15 points16 points  (5 children)

You've basically got it!

The arc on the left is liftoff, the first stage of the rocket carrying the payload off the ground.

That arc ends about 2.5 minutes in flight, as the main engine shuts down (the transition from yellow to red to blue). The second stage of the rocket separates and ignites, while the first stage pitches around and relights its engines to put it on a trajectory back towards Cape Canaveral (the bluish hook near the top of the arc).

The second stage is using just one engine, while the first stage uses nine, plus it's farther away, so its streak appears fainter.

That "boostback" by the first stage is the first of three burns that ultimately end with the landing.

The vertical pillar near the top is the second burn, the "re-entry" burn, which slows the rocket down from supersonic speeds to ensure it doesn't break apart when re-entering the thicker portions of the Earth's atmosphere. In this picture, you can actually see the transition points where the rocket was using one, then three, then finally one engine again, note on that vertical pillar where it gets thicker near the middle and thinner at the ends. The rocket is traveling "top to bottom" in the photo.

The pillar on the right is the landing burn, the third and final time the engines are re-lit on the first stage, as the rocket touches down gently at LZ-1, Cape Canaveral Air Force Station.

And yes, the other, fainter lines are star trails, recorded for nearly eight minutes while the shutter was open.

[–]night_of_knee 0 points1 point  (1 child)

[–]jardeon[S] 1 point2 points  (0 children)

Mostly; the blue streaks in the upper right are star trails, not the exhaust from the rocket. I think the first stage follows a "loopier" path on boostback, without the hard turn at the top of the arc.

[–]Cryogenicist 0 points1 point  (1 child)

How fast is it moving when the first stage turns around? I find it amazing that the first stage rockets can turn around, decelerate, and then return to the launch site.

[–]jardeon[S] 1 point2 points  (0 children)

From the SpaceX launch webcast, stage 1 is moving at over 4,000km/h when stage separation occurs.

[–]0hmyscience 5 points6 points  (0 children)

you can actually see the transition points where the rocket was using one, then three, then finally one engine again,

Wow that's awesome, definitely didn't notice that the first time.

Thanks for the detailed explanation! It makes this picture even cooler!