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.
Including features that are never used is bad design even if they don't compromise every other aspect of the design.
What mainly doomed the shuttle was the DoD requirement that the shuttle be able to pluck a satellite from a polar orbit in one orbit, making it necessary to include the massive wings so that it wouldn't be forced to land in the Pacific as the world rotated underneath it.
Yes it would. There's no such thing as a secret satellite, it's impossible to hide them. General astronomy would notice that their's one less satellite.
This is a bit of a partial myth. This idea was probably used when negotiating for funding in some quarters, but it was never a particularly plausible use of it, for at least two reasons. First, of course, the shuttle can only access extremely restricted orbits which most targets of interest would not be in. And second, countermeasures would be trivial if the Soviets believed such a threat to actually exist; just incorporate a few kilos of explosives into each device.
I'm reasonably sure this story was always more of a case of "how do we sell this thing" than "this is something that we can actually realistically do".
It was not built to retrieve Soviet satellites, despite an uncited claim in Wikipedia to the contrary. In fact, it probably couldn't. If nothing else, it'd be hard to fit a satellite designed for a different launch fairing into the payload bay of the shuttle and secure it well enough to be able to land with it. The shuttle was designed to bring cargo back, but only satellites that were specifically designed for this purpose.
What the Shuttle was designed to do in a military context is launch into a polar orbit from the coast of California, release a stealthy spy satellite, and return to Earth immediately after during the very same orbit (so about 90min from launch to landing). It therefore needed the very large wings to be able to glide back to Edwards Air Force Base in southern California, which would have rotated up to 1,500km away from the path of the orbiter. And because of the Pacific ocean, there'd be other landing sites available. This cross-range capability impacted every aspect of the design.
The idea was that big rockets which launch satellites are very easy to track, so it was hard to get a bird up without the enemy knowing its orbital path, and if the enemy knew the orbit they could evade overhead passes. So do a surprise launch on the shuttle, do a little orbit maneuvering while you are up there to maximize the enemy's uncertainty over its orbital plane, then immediately let go and land the shuttle--because otherwise they'd know where it was from tracking the shuttle.
I'm not sure if it was ever used this way, and the requirement is now obsolete anyway. You really can't hide a satellite from modern instruments, which have full global coverage, and its critical that orbits are known to avoid collisions in the much more crowded space up there.
Is the X-37b's orbit known? I dimly recall articles about observers catching glimpses of it places away from its predicted trajectory. Could it maybe be placing/observing/servicing satellites? Why's it a shuttle-style design?
I feel like it's not too outlandish to suspect that some military satellites might have a way to hide themselves from instruments, as well.
Known to the Russians and Chinese? Almost certainly.
The X-37B is a shuttle-like design because it was designed for NASA to be a crew escape vehicle for the ISS. The Air Force only took over the project when NASA cancelled it.
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.
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.
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.
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.
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".
I agree with you that hostile satellite recovery would be fraught with challenges. That said, I expect there are people who 'war game' these scenarios all day and probably have various counters or techniques to prevent damage to the shuttle or its bay.
I don't have access to classified military secrets, but you don't think they would build a vehicle that could return 15 tons of payload to earth to retrieve US satellites? US could just build and launch a new satellite easier and cheaper than bring one down to fix only to launch it again.
Obviously there is the movie about Salyut 7 that depicts the shuttle trying to capture the station. Salyut 3 had a machine gun attached to it.
Back in the 70s spy satellites used film cameras and used to return the film in re-entry capsules. There’s a _really_ good (fictional) move called Ice Station Zebra about a retrieval mission in the arctic that goes wrong.
Retrieving the satellite allows you to safely recover the film, and re-equip the satellite with new film and propellant. The latter is important because it’s useful for spy satellites to be able to change their orbits frequently to observe new targets or evade tracking.
Also bear in mind some spy satellites are huge and incredibly costly. The Hubble Space Telescope is based on a spy satellite series.
I read something about naval engagements with soviet ships. The US ships were trying to find something underwater before the soviets did while at the same time not alerting the soviet ships as to the location of what they were trying to find. It became clear they were both looking for one of these film canisters that maybe they weren't able to retrieve in mid-air. People today can't imagine the stakes during the cold war.
The main concern of the Soviets was that the Shuttle could swoop down and drop bombs without warning.
(Both Reagan and the Soviet top leadership didn't care about MAD, they cared about practical methods to stop incoming missiles. To get the arms limitations agreements signed, Reagan allowed the Soviets an exception to the anti-ABM ban to allow a ring of anti-ABM sites around Moscow, which exists until today. The "Star Wars" kinetic interception methods are also likely still active, though the laser methods probably never worked well.)
This is at the stage where you cant really make assumptions about what may happen because you don't know what could go wrong. (A.K.A you don't know what you don't know).
All you need to bring a traditional capsule design down to ~sea level terminal velocity safely is a blunt body with offset CG and the kind of circular ablative heat shield that's been shown over decades to be simple, safe and reliable. You don't even need active control unless you want more precision for hitting your landing target. The biggest risk, assuming your position and velocity were correct at interface, is the parachutes–which is why SpaceX took so much time testing and refining them.
Things can always go wrong, but we know enough about both classes of vehicle to be able to say that the Shuttle's design was in general terms both more complex and more risky.
This is slightly off topic, but the Shuttle was horribly unsafe on the way up as well as on the way down. Using solid rocket boosters with no means to get the crew safely off the stack until they stop burning is, for lack of a better word, demented. The Crew Dragon/Falcon 9 stack offers realistic abort modes from the moment fueling begins until the vehicle reaches its intended orbit.
I'm not claiming that OP or I are experts, but there's actually a pretty big body of knowledge for capsule re-entry. It's more 'known problems' than 'unknown unknowns'.
After reentry the next most dangerous part of the entire launch/return process is likely landing at sea and being rescued by helicopters or ships.
So I will be holding my metaphoric breath until the astronauts are delivered from SpaceX responsibility to NASA responsibility, which should be on land somewhere in Florida (too lazy to look it up sorry not sorry)
That is true, but it has only had one successful reentry (one out of one attempts) of a Dragon Crew capsule design (which, granted, is only slightly different than Dragon Cargo).
The Crew Dragon is very similar to the Cargo Dragon that has already had nearly 20 returns from orbit without incident, so there is already quite a bit of experience in the systems that will be used tomorrow.
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.
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.
Just to clarify, the error they were seeing was in an app running on an actual portable iPad they carry, not the main screens mounted in front of the seats.
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.
Undocking stream ran earlier and can be found at 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
The splashdown stream is at https://youtu.be/tSJIQftoxeU and starts at 4:25 AM PDT, with deorbiting expected around 10:55 AM PDT.
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.
Estimates set the lower bound at 250x the size of the observable universe, according to the limits of measurement of the "flatness" of our local space.
https://arxiv.org/abs/1101.5476
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).
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.
ISS circles Earth every ~1.5 hours, which is ~16 times per day, so it does makes sense to have UTC. Land however is fixed, with its own timezone. I second another answer, local timezone primary and UTC secondary is best.
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
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.
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?
We're not talking about the kind of system where you just turn on the rockets and it'll probably work okay here. Propulsive landing based on running 8 rockets is gonna take a ton of highly tested hardware and software, including speed and orientation sensors etc and all the software to balance things out perfectly.
No way they're adding in a big pile of extra untested software and hardware for an unlikely event. NASA would never approve, and correctly so, as that would be a massive number of extra things to potentially go wrong.
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.
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.
> 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.
Clearly not. NASA was already not keen about the superdraco system.
The explosion that destroyed the Dragon 2 capsule that was slated for the In-flight Abort test killed any chance of it being used for human-rated flights.
> Does that mean that it is officially not there
This is life-critical hardware/software. You don't go putting functionality in there that isn't approved by NASA, and most importantly the crew who're going to fly it.
Finding out that there's undocumented features and easter-eggs, even if they might in some very remote scenario help save life is certain to be outweighed by the risk that having it in there might somehow contribute to someone's death.
Could it be used for propulsive landing? Perhaps, but they'll first have to prove to NASA that it's safe - just like they proved to NASA that reused launch vehicles were safe, and reused Dragon 1 capsules were safe.
SpaceX seems to have given up on the idea of it anyway. They deleted landing legs from the capsule, and propulsive landing at sea as an emergency backup for the failure of all four parachutes (and you'd need to include a way to detect the failure, cut the chutes and then use the superdraco thrusters) seems a shitload of work which is probably going to only increase risk.
For propulsive landing of humans/cargo, it seems Spaceship their focus.
It means it's never been tested and there's no safe way to use it - the hardware and software are not configured to have that ability for this particular flight, is how I understand it.
It is there, just not certified for this use. However, if they manage to make a successful ememgency propulsive landing (even an unaccounted one), it will be investigated and then approved post-facto. The engines used for landing are the same engines that are used for post-second-stage maneuvreing.
I believe it to be no negative impact with one parachute failure and survivable with up to two parachutes of four failing. Down to just one parachute is probably bad news, and if they all fail then you die. Just like every other capsule.
Propulsive landing was not qualified, nor likely even finished, so I very much doubt it shipped. An untested propulsive mode is a significant liability.
They originally designed Dragon 2 for propulsive landing, but NASA didn't approve it, and then development focus shifted to Starship. I don't think anyone (outside of SpaceX) knows whether the feature still exists for emergency use; perhaps they never finished the software.
Both Soyuz and the Space Shuttle had fatal accidents on re-entry.