
NASA Astronauts Return Home in SpaceX's Crew Dragon Spacecraft [video] - jbredeche
https://youtube.com/watch?v=13OkD0C_TWU
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kanox
Not yet, not until re-entry. It's arguably the most dangerous part of the
missions since launching on Falcon 9 has happened many times before.

Both Soyuz and the Space Shuttle had fatal accidents on re-entry.

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caconym_
You're not wrong, but I think it's cool how much safer the generic capsule
design is than something like the Shuttle. Really the Shuttle got a whole lot
wrong—heat-intolerant aluminum structure and critical, sensitive machinery
directly beneath a layer of tiles so fragile you can crush them in your hands
(IIRC).

SpaceX's Starship will probably be a lot more tolerant to defects in the heat
shield because of the relatively heat-tolerant steel underneath, but landing
safely relies on the operation of massive aero surfaces _and_ a relight of the
engines with thrust vectoring. It'll be interesting to see how that goes.

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one2know
The Shuttle was built to bring down soviet spy satellites and spacecraft, so
in that regard, it was the best design made.

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whoisthemachine
Huh interesting. Do you have sources for that information?

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ChuckMcM
The idea that you could capture a satellite and return it was part of the
mission requirements for the original shuttle design. If it was a 'friendly'
or 'unfriendly' satellite was left unspecified.

It was also limited by the Shuttle's OMS in terms of delta-v so the orbits
from which a satellite could be retrieved was constrained.

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drran
Unfriendly satellite can blow up or cause fire inside of shuttle, so it's bad
idea to capture enemy satellites. It's like sending billion-worth mine
capturer behind enemy lines, which can be destroyed with AK.

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marvin
Don't see why you're downvoted for posting this. Certainly, satellites
designed before the Space Shuttle would have to be very paranoidly designed to
include a self-destruct mechanism, but it only takes a couple kilograms of
explosives to strongly disincentivize kidnapping it.

If I was a military satellite designer, heaven forbid, I'd definitely include
that in a world that included the possibility of stealing satellites. The
capability, quietly communicated between the powers, would be enough to ensure
that the satellite would never be stolen. And therefore, the billion-dollar
kidnapping capability becoming useless.

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gregoriol
Even without self-destruct, a satellite not programmed to be captured could
simply fire some thrusters if it detects an orbit change, and that would
likely make some big dammage inside the capturing shuttle.

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yencabulator
That's typically ion thrusters, isn't it? That's very low mass at very high
speed, and would probably take hours to even leave scorch mark. It would feel
like a slow breeze.

Of course, military use could do something different, but that's more along
the lines of "pack a kilogram of explosives in a pipe bomb".

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jacobush
Hydrazine thrusters more likely. Ion thrusters are novel.

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raldi
Mods, a better headline would say "returning", or that they've departed the
ISS. They haven't returned to the surface yet.

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pjfin123
I can't easily link to it because it's still live streaming but at 4:10 in
they seem to be debugging a local internet/HTML error on their iPads. Next
level debugging in production.

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TeMPOraL
Related, I wonder if there's going to be a postmortem on this mission on the
UI, because from the brief scenes when its shown updating or being clicked on,
it looks to have a responsiveness on the order of _half a second_.

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m0xte
Think it’s Electron. Doesn’t surprise me. I wouldn’t want to take slack into
space with me.

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madeofpalk
I'm fairly certain there's no Electron on iPad (can't take Chrome to iPad). I
also don't think that a native wrapper app that loads (local) html files would
display a "Safari" error message.

It was probably just a cached/saved website saved to the home screen. I'm not
a rocket scientist, but as a web developer, I would rely upon that for
anything earth-bound, let alone in Space.

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interestica
> I'm not a rocket scientist, but as a web developer, I would rely upon that
> for anything earth-bound, let alone in Space.

...would?

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madeofpalk
would NOT. Yikes.

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throwawaysea
Undocking stream ran earlier and can be found at
[https://youtu.be/13OkD0C_TWU](https://youtu.be/13OkD0C_TWU), with the
undocking procedure beginning 2 hours 14 minutes in. The actual separation is
at 2 hours 19 minutes.

Currently there is a live stream of the autonomous “return coast” phase while
the crew sleeps: [https://youtu.be/zMsxviPT2Cw](https://youtu.be/zMsxviPT2Cw)

The splashdown stream is at
[https://youtu.be/tSJIQftoxeU](https://youtu.be/tSJIQftoxeU) and starts at
4:25 AM PDT, with deorbiting expected around 10:55 AM PDT.

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yesenadam
The first comment I saw in the live chat was "You people have it wrong, space
is flat, not earth".

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cheschire
Well from what I’ve read the observable universe is fairly flat, but I was
wondering what if we’re just living in a basin or on a plateau that extends
beyond our observable reach?

I suck at math though so I’ll just wait for theoretical astrophysicists to
tell me interesting things on blogs.

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tomphoolery
Then we can all say we live "in the Valley"!

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komali2
We all live in the valley on this blessed day

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iblaine
The SpaceX crew land in Florida at 2:48 p.m. ET on Sunday.

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Jaruzel
Or 19:48 for those of us in the UK.

NASA/SpaceX really should start using UTC for their timestamps.

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kelnos
I feel like it's not at all weird to say that something is arriving somewhere
in that somewhere's local time zone.

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CydeWeys
More importantly, that's the timezone Mission Control is in. There are no
timezones in low Earth orbit because you're orbiting every 90 minutes, so the
only timezone that's relevant to anyone involved in the Mission is the one
that all the hundreds of ground personnel are using (in Mission Control and to
a smaller extent on the recovery ship).

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skissane
From my understanding, mission control usually doesn't use their own local
time. The choice of time depends on the mission, but common choices are UTC or
Mission Elapsed Time. The ISS missions use UTC, since the ISS is jointly
controlled by Russia and the US, and neither would agree on using the other's
local timezone(s), so they use UTC.

Stuff published to the public is not coming directly from mission control, it
is being filtered through NASA PR and SpaceX PR. And PR often tries to
simplify things for their audience, like converting UTC (which the average
person isn't very familiar with) to local timezone. (And sometimes NASA PR
also likes to turn metric into US customary, although SpaceX PR does that
less.)

The primary target of NASA and SpaceX's PR is American voters, because it is
American taxpayer money that pays for all this. Putting things in terms which
makes it easier for an American to understand, but harder for a non-American,
makes sense in that context.

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dencodev
Re-entry happening some time tomorrow. Cool to see the ISS separation though!

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dghughes
I waited all day to see it live but then I had to take the cat in from
outside. And missed the live undocking. Plus I got bitten.

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mechhacker
Really glad I got to drive out and watch this launch.

It was fantastic seeing us send people back into space again.

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bserge
Perseverance also launched a few days ago:
[https://mars.nasa.gov/mars2020/](https://mars.nasa.gov/mars2020/)

Hopefully the landing is just as smooth as Curiosity's.

It would be really cool to see actual, high quality footage of it, but at
least there's the simulated renderings. Extremely impressive.

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jvm___
There are multiple landing cameras this time.

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marmshallow
*are returning home. They haven’t made it back yet. They are on track to land 11:48am PT on Sunday

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Animats
What's the link for the technical feed? Right now someone is filling time with
a history of the ISS.

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dylan604
Hit the rewind button to see the departure. All of the "action" is pretty much
done for today. They are now just floating through space waiting for the next
burn. Tomorrow afternoon will be the re-entry an splash down activity

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nicholascamera
The ship departs from the station at 2 hours 19 minutes.

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mkl
The video seems to be no longer live, so times have changed (?). Undocking now
starts at 6m45s:
[https://youtu.be/13OkD0C_TWU?t=400](https://youtu.be/13OkD0C_TWU?t=400)

Physical separation is at 11m35s:
[https://youtu.be/13OkD0C_TWU?t=695](https://youtu.be/13OkD0C_TWU?t=695)

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tjpnz
What happens in the event of a parachute failure? Would they be in a position
where they could fire up the Super Dracos for a propulsive landing?

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paranoidrobot
There are four parachutes. It's designed to support at least a single-chute
failure, I don't know about multiple chute outages.

As for propulsive landing - the latest I can see[1] is that while the craft is
technically capable of propulsive landing, it's not approved by NASA, even for
emergencies. So it's likely that these options are not even available for the
crew, and they wouldn't have trained on how to use it/activate it.

[1] [https://www.teslarati.com/spacex-crew-dragon-emergency-
landi...](https://www.teslarati.com/spacex-crew-dragon-emergency-landing/)

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sebazzz
Not even for emergencies? Does that mean that it is officially not there, but
in the unlikely unlikely event it can be used, or that it really isn't there
anymore and the capsule would just drop dead on the ground?

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paranoidrobot
Further reply, this question was just asked and answered on the new live-
stream.

Official response from SpaceX: Superdraco thrusters are completely inhibited
once the launch is sucessful.

So, no, not even as a backup.

Also, one other thing I remembered - the draco and superdraco thrusters
require different pressurisation levels for their fuel systems. Before launch,
the system is put into a high pressure mode, to enable launch escape. After
they make orbit, the system is depressurised back to enable the draco
thrusters to operate.

So they'd need to have time to re-pressurise the system, too.

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anticensor
Repressurisation hardware has to exist anyway to have restartability (it takes
15 minutes to switch to high pressure feed, 15 seconds to low pressure feed).
Do you know which component has inhibition affected? SW only? Blown fuse?
Something different? Certainly not a jettisoned part, because this vehicle is
planned to be reused after minor refurbishment.

PS re repressurisation failures: If it becomes absolutely necessary, a
procedure could well be devised to operate the larger thrusters at a lower
flow rate, albeit with a diminished efficiency and thrust.

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paranoidrobot
> Do you know which component has inhibition affected? SW only? Blown fuse?
> Something different? Certainly not a jettisoned part, because this vehicle
> is planned to be reused after minor refurbishment.

They didn't elaborate, it was a 30 second response.

