31
votes
Recap: SpaceX successfully launches Crew Dragon with Bob Behnken & Doug Hurley on SpX Demo-2 mission to the ISS, restoring US spaceflight for the first time in nine years
Decided I'd post a text post and provide links to all the content, since there's so much and it's all quite diverse. I'll update this post throughout the day with more content:
- NASA Press Release: NASA Astronauts Launch from America in Historic Test Flight of SpaceX Crew Dragon
- Live stream & launch video, courtesy SpaceX & NASA. This is going to be live all the way through to docking with the ISS.
- NASA Spaceflight (Good resource, quite in-depth): SpaceX Dragon’s historic launch dodges weather to launch and end the gap
- SpaceNews: Crew Dragon in orbit after historic launch, by Jeff Foust
- The Verge: A cute stuffed dinosaur hitched a ride on SpaceX’s historic launch
- The Verge: Watch NASA astronauts fly SpaceX’s Crew Dragon using touchscreens
It was cool as fuck. I know logically there are arguments against the various space programs, money could be spent elsewhere to help people who need it, arguments against private companies involved in space, military/security/political arguments, etc. but fuck, it was awe inspiring to watch and i'm a miserable bastard. They put two men into space and landed the rocket that sent them in less time than it would take me to nip to the corner shop and buy a bottle of milk. Crazy.
My favorite fact about the Falcon 9 is the incredible speed of the Falcon 9 first stage when it's landing back on land. The launch pad and landing pad are about 10 miles apart (~16km) by road, and it takes the Falcon 9 first stage about 10 minutes after its launch to land on the landing pad. If you wanted to drive from the launch pad to the landing pad and beat the Falcon 9 first stage, you would need to drive at an average speed of at least 60mph.
So the flight starts when the booster ignites its nine engines on the ground. These engines can produce a combined total of 1.7 million pounds of thrust (~7561 kN), able to lift of about 85 elephants (or a fully-fueled Falcon 9.) Around a minute into flight, as the vehicle breaks the sound barrier, the engines are all throttled down a little bit to reduce the forces on the vehicle (remember, it's flying at supersonic speeds through the relatively thick lower atmosphere; reducing thrust just a little bit can reduce the peak aerodynamic stress levels quite noticeably.) A few seconds later, as the atmosphere thins out again, the engines throttle back up to full thrust.
The booster passes through Mach 5 on the way up, then shuts off its nine engines and separates from the upper stage (which makes its way into orbit with the payload.) The booster immediately flips itself around and fires the engines to invert its ground path (because it's flying Mach 5 in mostly the wrong direction.)
While casually blowing through the Kármán line (100km altitude), it orients itself engines-down; then, a few minutes later (while it's falling back through the atmosphere at several times the speed of sound), it restarts three of its engines to slow itself down. If this entry burn isn't done, the booster would burn to pieces during re-entry. (Even though it's not going anywhere near as fast as spacecraft returning from orbit, the booster isn't shielded very well, so it needs to slow down using engine power.)
After the entry burn ends, the booster uses its grid fins to glide towards the landing pad. The Falcon 9 booster flies much like a dart; the engines are extremely heavy, like the nose of a dart; and the grid fins (at the top) are like the fletching of a dart, keeping it pointed in the right direction; unlike a dart though, the grid fins work well even supersonic and transsonic, and they're movable as well (so the onboard computer can precisely aim the Falcon 9 as it falls.)
Then, only about 10 seconds before it would hit the ground and explode, it restarts the center engine to slow itself down. A few seconds before touchdown, it unlocks and deploys the four landing legs, constantly adjusting the engine thrust to maintain its target of zero vertical velocity at touchdown. (Since the minimum thrust of a single engine is greater than the weight of the booster, it can't hover; and therefore must perform a 'suicide burn' to land safely.) Once it touches down, the engine is shut off, the launch director says "The Falcon has landed; landing operators move to procedure 10.100," and the propellant tanks are vented one-at-a-time to reduce pressures from 50psi to a lower level.
Which is when the car rolls onto the pad. It's been driving 65mph for the last 10 minutes, and has now broken both the local speed limit and the obvious rule of not being near rockets in flight. That's how fast rockets are.
Unfortunately, today's awesome spaceflight news was stained and somewhat overshadowed by the political and social upheaval that's occurring over the U.S. at the moment—I can't help but feel somewhat muted about the success of the event. Things... could be better.
Politics is politics and science is science. Tensions between America and Russia are high right now too, but right now there's two Russians and three Americans, all representatives of their respective governments, trusting each other completely. Everyone who has been to space says the same thing: seeing the Earth from the space station makes borders and class divides look completely arbitrary and meaningless.
What makes space exploration so inspiring for me is that it continues despite upheaval on Earth. It reminds us of what we are capable of at our best, and reminds us that we can do better on the ground.
Not when you've got DJT himself giving speeches at KSC—and attempting to further hate by indicating he'd like to strap journalists on the rocket if he could.
It’s hard to get people excited for space if they’re miserable on Earth. Calling society's significant problems meaningless—even if only from the perspective of space—is going to fall on many deaf ears.
Space advocates need to realise that—ironically—they don’t exist in a vacuum, and attempting to appeal to a sense of unity when there's so much fragmentation going on gives off privileged vibes, which can actually further discord. Strong bet neither you or I are heavily experiencing the upheaval on the streets right now.
Let's celebrate this accomplishment, but we can't deny it takes place during a time of social upheaval, so it's sensible to frame it appropriately.
You're right. I feel like many STEM outreach programs attempt to target underserved communities, and I suspect that those who are able to take advantage of those opportunities have a better chance of upward social mobility. It's important to not alienate those groups when talking about space exploration.
Overall I agree with you, but I nevertheless haven't stopped bouncing up and down all day in giddiness over SpaceX and NASA's accomplishment.