SpaceX Falcon 9 / Dragon 2 : SpX-DM1 : March 2, 2019 : DISCUSSION

[Rocket Science]

Anyone got a link to the video of the sea recovery ops?   The vids I watched show the fast boats approaching ; then it cuts off.   I'm wondering if it takes 2 minutes or 10 minutes to get to the capsule.
Also, I'd like to see what things are done during the recovery.

Interesting to note that 5 of the apollo capsules ended up inverted in the water:
https://history.nasa.gov/SP-4029/Apollo_18-40_Entry_Splashdown_and_Recovery.htm?fbclid=IwAR1JAzUIgqBnEpZwS68P8dJfTj3Gg45ODznkcLtPhdWv6AL8BYaUhURs0Es

I'm disappointed that NASA wouldn't let SpaceX develop its preferred landing methodology ... which would not have any of these complications and potential dangers.    That being said, it appears to be no more or less troublesome than mercury, gemini, and apollo.

From yg in the update thread:

[Rocket Science]

Not to rain on what is a great day however all the monkey motion under the chutes and

Not sure what monkey motion is but I saw the capsule being EXTREMELY stable under the chutes - no pendulum motion and no spin at all. In general more chutes make the capsule more stable and I think the lateral sliding that the canopies were doing was by design - canopies drift around, capsule remains stable.

I agree about the bobbing in the ocean though, that doesn't look like much fun. The relatively tall Dragon looks like it is pitching over a lot more with each wave than the much more squat Apollo capsules, because of it's relative height. I wonder if hey considered an inflatable donut for Dragon like the Apollo capsule had?

Oscillation under the drogues that gets dampened out when the mains deploy... Could be "vortex shedding" which can occur with airflow around a 'blunt body".  They'll look at the aero data and what Ripley felt... (see above video)

[punder]

Not to rain on what is a great day however all the monkey motion under the chutes and

Not sure what monkey motion is but I saw the capsule being EXTREMELY stable under the chutes - no pendulum motion and no spin at all. In general more chutes make the capsule more stable and I think the lateral sliding that the canopies were doing was by design - canopies drift around, capsule remains stable.

I agree about the bobbing in the ocean though, that doesn't look like much fun. The relatively tall Dragon looks like it is pitching over a lot more with each wave than the much more squat Apollo capsules, because of it's relative height. I wonder if hey considered an inflatable donut for Dragon like the Apollo capsule had?

I joked that the DM-2 crew were now asking for a flotation collar.

The Navy astronauts might be fine, but the AF astronauts might be a little put out. On the other hand, what's a little puking compared to the privilege and honor of flying in space. I doubt the astronauts are going to care that much.

[b0objunior]

Nice video on the highlights of the whole mission!

[crandles57]

I tend to doubt sea sickness is much of a problem for the astronauts. I did wonder about safety of fast boat crew climbing onto dragon if the sea was a lot rougher.

Wondering if those fast boats could take an inflatable collar that could be attached around dragon to make climbing on safer. In choppier / bigger swell could perhaps it be possible to slowly tow dragon using that inflatable ring such that dragon in the wake of fast boat is a little calmer so working on outside of dragon to attach hoist ropes is easier. Perhaps they just position go searcher to put dragon is in lee of ship in such conditions?

[ATPTourFan]

Remember that even with Cargo Dragon, if sea state and weather was unfavorable and unsafe for recovery crews, the departure from ISS would go to a contingency date. Let's not worry so much about this. DM1 was perhaps one of the most worried about missions in a long long while between NASA and SpaceX and what was on the line, even uncrewed.

[Herb Schaltegger]

Remember that even with Cargo Dragon, if sea state and weather was unfavorable and unsafe for recovery crews, the departure from ISS would go to a contingency date.

Exactly. People seem to forget that shuttle returns were routinely delayed due to weather concerns at the landing sites. No big deal here at all. The only time recovery weather would be a concern at all would be an emergency station evacuation, and even then, if there was a hurricane in the recovery zone, SpaceX/NASA would put contingency plans in place to splashdown elsewhere, even if it required requesting DOD support for recovery or something.

Recovery weather is a non-issue for nominal operations.

[Zed_Noir]

Wonder how far can SpaceX divert a returning Dragon from orbit? In order to avoid bad weather in the original landing point. Not switching to the gulf of Mexico, just somewhere else on the Atlantic coast..

[Jcc]

Was there any announcement or non-announced info on the accuracy of the splashdown location? We know the time of splashdown was right on the money, exactly as planned. That is a good sign that the models are correct.

The more accurate they are, the closer in the recovery ship can be, reducing the time to recover.

[kevinof]

Looking at how far the ribs were and how long it took to reach the Dragon , I would say a couple of miles, no more.

Was there any announcement or non-announced info on the accuracy of the splashdown location? We know the time of splashdown was right on the money, exactly as planned. That is a good sign that the models are correct.

The more accurate they are, the closer in the recovery ship can be, reducing the time to recover.

[AndyH]

Was there any announcement or non-announced info on the accuracy of the splashdown location? We know the time of splashdown was right on the money, exactly as planned. That is a good sign that the models are correct.

The more accurate they are, the closer in the recovery ship can be, reducing the time to recover.

There is L2 info.
https://forum.nasaspaceflight.com/index.php?topic=46703.msg1919853#msg1919853

(L2 rocks - and there are server hamsters to be fed.  )

[Thorny]

It appears that the Charleston area was treated to a sonic boom from the returning Dragon...

http://www.live5news.com/2019/03/08/sonic-boom-reported-across-lowcountry-friday-morning/

[Jcc]

https://twitter.com/elonmusk/status/1104090692215726080

Noticing that the coating (SPAM?) covering the black Superdraco bay is intact. If the covering on the Superdraco nozzles held up, they may have stayed dry, greatly facilitating refurbishment.

[CorvusCorax]

Wonder how far can SpaceX divert a returning Dragon from orbit? In order to avoid bad weather in the original landing point. Not switching to the gulf of Mexico, just somewhere else on the Atlantic coast..

There's two things that come into play:

1. Orbital mechanics. The Dragon reenters in the same plane as the ISS, its path brings it down somewhere along a line that runs straight all across the ocean and in fact all around the planet. A minute more or less for the reentry burn translates to roughly 450 km further or less far along that trajectory. They can aim from close to short up thousands of miles downrange.

While the capsule orbits, the earth rotates under it, so if you wait an extra orbit or one orbit less, you can go east or west in steps of roughly 2500 km (equator crossing), by waiting 90 minutes or going 90 minutes earlier.

Now the orbit is inclined by roughly 51 degrees, so if you paint 51 degree orbital lines from the equator at 2500 km intervals and intersect them with the US east coast, then you get to a couple hundred kilometers between each intersection. So those are basically the points at the shore where they can easily come down without changing the reentry timing by more than a few hours.

Of course the constellation of intersections repeats a little bit different every day, so you get additional locations when you wait extra days.

2. Where can you get the ships in time. The recovery vessels are a lot slower than the capsule (obviously) and at sea can take several day to get from one of these locations to the next - unless you want to rely on local fisher boats. This is the more limiting factor.

So first, you need to look at the orbit/coast intersections for a given day.
Then you need to look at the weather report, your fleet status, find out where you can gather the recovery fleet safely.
Once you have the fleet in place, its relatively easy to make the capsule come down there. Unless something goes wrong with reentry, then you might end up a thousand miles off course. (Soyuz did that a few times )

[Comga]

Splashdown !

SpaceX have posted a higher-res version of splashdown on their website (attached).

Despite claims up-thread, one can see from the closeness of the base of Dragon to the horizon, this video was not shot from a plane at 18k ft as claimed.
From 18 kft, the horizon is over 250 km away.
Plus the video was more stable and from a more constant distance and angle than is possible from a moving plane.

[Grandpa to Two]

Under the side hatch is an open hatch. This photo taken from NASA video shows water sloshing in the bottom of the compartment. I’d like to know what was in there and when did it open.

[DatUser14]

Under the side hatch is an open hatch. This photo taken from NASA video shows water sloshing in the bottom of the compartment. I’d like to know what was in there and when did it open.

thats the main parachute compartment.

[rickl]

Under the side hatch is an open hatch. This photo taken from NASA video shows water sloshing in the bottom of the compartment. I’d like to know what was in there and when did it open.

thats the main parachute compartment.

I was pretty disgusted seeing seawater sloshing around in there.

I understand that NASA put the kibosh on SpaceX's idea of propulsive landings.

But I've also read that NASA wants new Crew Dragons for each flight.

That means that SpaceX could build up a stockpile of used Crew Dragons that could potentially be used for private missions.  Could they be used for propulsive landing flight tests?

[deruch]

Under the side hatch is an open hatch. This photo taken from NASA video shows water sloshing in the bottom of the compartment. I’d like to know what was in there and when did it open.

thats the main parachute compartment.

I was pretty disgusted seeing seawater sloshing around in there.

I would imagine that the Dragon 2s are designed similar to the Dragon 1s in terms of reusability.  If so, then flooding in the parachute compartment is at least partially a benefit.  Here's a comment on /r/SpaceX from a former SpaceX intern who was working on reusability improvements to Dragon 1 capsules during his time there: Direct link

They also have plans to reuse the majority of the service section. When I interned there, we were working on making adjustments so that the service section would not flood with ocean water during the landings. This mainly included sealing the service section, installing a bilge pump to remove water that leaked in, and installing an ocean heat exchanger.

As you may know, when Dragon is in space, it cools itself using a radiator located on the trunk. Before reentry, the trunk is jettisoned and then Dragon has no way to cool itself. During reentry, the heat from the electronics in Dragon is building up inside of Dragon's thermal control system (TCS) loops which are located in the service section. Previously, the service section would flood with ocean water and the heat would flow from the TCS lines into the water. But now that the service section is sealed the only area that floods with water is the parachute bay, so we installed an ocean heat exchanger there. The ocean heat exchanger is essentially just as much surface area of tubes that could fit in the space we were given.

[Herb Schaltegger]

Splashdown !

SpaceX have posted a higher-res version of splashdown on their website (attached).

Despite claims up-thread, one can see from the closeness of the base of Dragon to the horizon, this video was not shot from a plane at 18k ft as claimed.
From 18 kft, the horizon is over 250 km away.
Plus the video was more stable and from a more constant distance and angle than is possible from a moving plane.

That last video segment with the actual splashdown seemed to me very much like it was being shot from one of the recovery vessels. The IR tracking video segments from plasma trail through drogue chute deployment were clearly shot by a stabilized camera mounted on the NASA WB-52 flying at roughly 18K feet, as the aircraft altitude was displayed in the upper right corner the whole time.