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

[Rondaz]

Demo-1 Launch Ushers in ‘New Era in Spaceflight’

Anna Heiney Posted on March 2, 2019

The Demo-1 uncrewed flight test to the International Space Station, SpaceX’s inaugural flight with NASA’s Commercial Crew Program, is underway following the successful launch Saturday morning of the company’s Falcon 9 rocket and Crew Dragon spacecraft. The first-of-its-kind mission, planned to be a full demonstration of the spacecraft and its systems, launched on time at 2:49 a.m. EST from Launch Complex 39A at the agency’s Kennedy Space Center in Florida.

Demo-1 is the first flight test of a space system designed for humans built and operated by a commercial company through a public-private partnership. The mission also marks a significant step toward returning to the nation the capability to launch astronauts on a U.S.-built spacecraft from U.S. soil.

“It’s an exciting evening,” NASA Administrator Jim Bridenstine said after the launch. “What today really represents is a new era in spaceflight. We’re looking forward to being one of many customers in a robust commercial marketplace in low-Earth orbit.”

Elon Musk, SpaceX CEO and lead designer, expressed his thanks to the SpaceX team and reported that the Crew Dragon spacecraft performed as expected through launch and ascent.

“We’re only partway through the mission, but the system thus far has passed an exhaustive set of reviews, and the launch itself,” Musk said. “The launch went as expected and so far everything is nominal.”

In addition to 400 pounds of supplies and equipment, Crew Dragon is carrying Ripley, an anthropomorphic test device outfitted with sensors to gather important data about what an astronaut flying aboard the spacecraft would experience throughout the mission.

NASA and SpaceX will use data from Demo-1 to further prepare for Demo-2, the crewed flight test that will carry NASA astronauts Bob Behnken and Doug Hurley to the International Space Station. NASA will validate the performance of SpaceX’s systems before putting crew on board for the Demo-2 flight, currently targeted for July.

Crew Dragon will carry out a series of phasing maneuvers as it pursues the space station during approach. The spacecraft is scheduled to autonomously dock to the station’s Harmony module forward port tomorrow, March 3, at about 6 a.m. EST. It will remain docked until approximately 2:30 a.m. on Friday, March 8. Crew Dragon is expected to return to Earth with a splashdown in the Atlantic Ocean at approximately 8:45 a.m. on Friday, March 8, a little more than six hours after departing the space station.

https://blogs.nasa.gov/commercialcrew/2019/03/02/demo-1-launch-ushers-in-new-era-in-spaceflight/

[Comga]

I wasn't sure where to post this comment but I guess here is as good as any.  The interior of the Dragon 2 capsule as you would expect from Musk: is clean, smooth lines, uncluttered, minimalistic yet functional.  It appears to have been designed by an auto designer Ha Ha.  On the other hand the interior of the ISS is just the opposite and looks like a science experiment, because IT IS a science experiment.  That being said I would expect to see the same interior design philosophy of the Dragon 2 being carried over to the Starship.  I can't wait to see the first real renderings or hardware in place for the Starship interior.  That shouldn't be too much longer.

Spot on
I saw the Apollo 11 documentary the day before the DM-1 launch.
There are images of both capsule and launch control facility in both videos.  (It's the same control room!)
Not that either are capable as those for Apollo, (You know what I mean.) there is a stark contrast for both.
Classic 1960's technology and utilitarianism for Apollo 11. 
21st century technology and Musk's particular aesthetic for DM-1. 
Both are perfect for what they are.

[Comga]

I really wish at one of these many press conferences that someone asked if the D2’s will return to Earth with all of its unused hypergolic propellant onboard, or if it dumps it at some point.

Being an (software) engineer, I would prefer to keep the super dracos as options all the way till landing.  My bet would be that have the old propulsive landing routines buried in their emergency software decision tree as a last resort if the capsule is in free fall after a certain altitude (turned off once the vehicle is safed.)  Complete conjecture on my part with no basis in known facts...

Not sure Dragon even has a radar altimeter - doubt it could accurately determine it's height above ground in order to control the thrusters.

As much as many of us would love to see this come down on land, it ain't going to happen.

My emphasis
That brings up an interesting question
How could Dragon determine its altitude with precision?
I had an idea and then I saw this object at the top of the window beside the hatch.
Any idea what it could be?
A downward facing camera?
A stereo camera?
A lidar?
A radar?

[JimO]

So can anybody work out the preliminary entry ground track next week? Because maybe [?] it's going to be nighttime and [if descending node] will cross populated areas of North America. The much bigger shuttles made SPECTACULAR entry fireballs across the US [I saw four or five, and even when it was forty mile up we could hear the MUCH later sonic boom ['thud' would better describe it].  And numerous witnesses reported the 'electrophonic sound' phenomenon caused by radio bursts from the plasma tail exciting materials in the earwitness vicinity, the old real-time audio bolide effect that baffled scientists for centuries.  http://www.jamesoberg.com/96mar-sts72_entry.pdf

[daveklingler]

I really wish at one of these many press conferences that someone asked if the D2’s will return to Earth with all of its unused hypergolic propellant onboard, or if it dumps it at some point.

Being an (software) engineer, I would prefer to keep the super dracos as options all the way till landing.  My bet would be that have the old propulsive landing routines buried in their emergency software decision tree as a last resort if the capsule is in free fall after a certain altitude (turned off once the vehicle is safed.)  Complete conjecture on my part with no basis in known facts...

Not sure Dragon even has a radar altimeter - doubt it could accurately determine it's height above ground in order to control the thrusters.

As much as many of us would love to see this come down on land, it ain't going to happen.

My emphasis
That brings up an interesting question
How could Dragon determine its altitude with precision?
I had an idea and then I saw this object at the top of the window beside the hatch.
Any idea what it could be?
A downward facing camera?
A stereo camera?
A lidar?
A radar?

It looks an awful lot like a window latch, but I'd give it better odds of being a camera. And if it were my choice, I'd mount it looking straight out the window, to show what it's like to look straight out the window.

[Herb Schaltegger]

Just catching up with the thread ...

I set an alarm and woke up at 1:15 AM CST to watch. For everyone complaining about the stream video quality, I gotta wonder about your ISPs more than Youtube or SpaceX. I have fiber-to-the-home internet (3 years now) and a gigabit connection. Didn't have a single quality issue at all from the time I started watching at about T-minus 30 minutes all the way through Dragon sep. I wasn't switching between streams to compare to NASA's, but SpaceX's was fine.

As for the new curved mission timeline, I think it's great. Keeps the relevant place to look at a constant location all the way through, which is ideal for a quick-glance grasp of information. Ever wonder why your GPS map display in your car or a pilot's FMS system maps keep your position in the center and scroll as you move? That's why. Finding a location along a static plane or even a line takes more time and concentration that keeping the focus-point fixed and scrolling information around that point.

I didn't stay up post-sep for the presser, though I watched it later this morning. Elon looks EXHAUSTED. The man needs to delegate a bit more and get some sleep. He's gonna have a stroke or heart attack; that won't do anyone any good. Bridenstine impressed me. When nominated, I expected him to be a typical Administration Party apparatchik. He comes across as quite a bit less of that, and quite a bit more capable and willing to learn. So good on him.

Now let's see how rendezvous, prox ops and docking go tomorrow, and then EDL 5 days later before we call it all an unqualified success. But DM-1 is off to a great start, and that's encouraging on many fronts.

[ppb]

Why barge and not land landing for the first stage?

I thought it would have enough performance for coming back to cape canaveral on this kind of payload.

A guess only but it's possible that they didn't want the spacecraft in close proximity to the plume of a boost-back burn

Don't guess  (edit: bad guess)
Read back through the thread
It has been asked and answered several times.

That curved event list is a cool design. Not the most practical maybe, but it looks cool.

Gonna have to disagree in the very strongest possible terms.

I agree with you Prettz.  This trend toward blocking the view in launch webcasts (ULA did it with an ugly crawl) is beyond bad.  I don't mind having a data display, but why not move it out of the video frame?  It worked when they did the split screen when it didn't block the view, but when they showed a single frame it blocked important parts of the view, including the launcher, the exhaust plume, part of the Vacuum Merlin, and so on.  I didn't like the previous SpaceX status bar, which covered the bottom 10% or so of the frame.  Now they've replaced it with something 3-times taller.  Who comes up with this stuff?  Horrible.

 - Ed Kyle

Agree. I really don't like the new display. It's distracting and ugly.

This trend started a long time ago on TV, it was football broadcasts where I first noticed, to my great annoyance, that the networks insisted on plastering their logo along with the score on the screen. I felt like someone had slapped a sticker over my screen that I couldn't peel off. The trend has only grown worse over time to the present age of the internet, where online viewing of many websites is near impossible because of pop-ups. The Masters of Communication will keep messing with our viewing experience as long as we keep watching.
( mods: sorry about the rant, but this was a long winded way of saying I'm also bothered by showing us anything else beyond elapsed time and maybe altitude and speed on the launch video feed)

[kevinof]

Anyone notice if any "damage" was done to the crew access arm on liftoff? Did the exhaust from the F9 catch it at all?

[Rondaz]

Great picture inside the crew access arm..

https://i.redd.it/ed7dayyjxqj21.jpg

[Roy_H]

SpaceX Demo-1 Post-Launch News Conference
http://www.space-multimedia.nl.eu.org/index.php?option=com_content&view=article&id=6658

Thankyou for posting this as I did not stay up to watch it live. However I am generally disappointed on the low quality questions in these briefing. More than 75% are Elon, how do you feel about.... all general emotional questions. I want to see answers to technical questions, the best one was about the grid hydraulic pump failure. If I was able to ask a question I would like to know why SpaceX takes 27 hours to rendezvous with the ISS and the Russians take only 4 hours.

[CorvusCorax]

SpaceX Demo-1 Post-Launch News Conference
http://www.space-multimedia.nl.eu.org/index.php?option=com_content&view=article&id=6658

Thankyou for posting this as I did not stay up to watch it live. However I am generally disappointed on the low quality questions in these briefing. More than 75% are Elon, how do you feel about.... all general emotional questions. I want to see answers to technical questions, the best one was about the grid hydraulic pump failure. If I was able to ask a question I would like to know why SpaceX takes 27 hours to rendezvous with the ISS and the Russians take only 4 hours.

Agreed about the questions. EverydayAstronaut really offset it with the hydraulic pump, though, made my day. And Elon turned a few of the more boring questions around by talking about specifics of the mission and the risks.

I can answer your question about the quick rendezvous.

To rendezvous with an orbiting spacecraft - such as the station - you need to wait until the earth is turning so your launch-pad is exactly aligned with the orbital plane - while the earth constantly rotates. This means, unless you are capable of doing very expensive high deltaV plane-change manouvers, you end up with an instantaneous launch window.

Now the problem is, that you end up in that exact perfect spot only once every 24 hours, as the earth rotates. But in order to have a "short rendezvous" trajectory, where you basically just launch and are already on approach, you also need to launch just as the spacecraft you want to meet is passing overhead. Usually it does that every 90 minutes, give or take, since that's the orbital period for everything in low earth orbit.

Now there you have the problem. These two events need to coincide. The vehicle/station needs to pass overhead exactly over your launch location in order for you to make a quick rendezvous. And that doesn't happen often. Usable close pairings happen only about once a month. And even then, it often requires orbit-changes or adjustments of the station itself to make it match perfectly.

If you want to launch on any other day (for example because you had to scrub doe to weather, or because the schedule up on the station doesn't allow a dock on that particular day) you end up being a quarter orbit or half an orbit phase-shifted.

And that means you need to slowly "phase". Usually. as is the case with dragon, you are "behind" the target object, so you go into a lower orbit with a shorter orbital period, so you slowly "catch up" with the station over the course of quite a number of orbits.

The closer you get, the higher you raise your orbit, until you have the station in sight and are practically in the same orbit and can start relative motion maneuvers for a docking or capture approach.

That's the normal procedure, and thats usually done for cargo or unmanned vehicles, because its just a lot less hazzle. You can launch on any day instead of just once a month, and you don't have to fiddle with the stations thrusters for orbit fine-tuning, only with the approaching vehicle.

Now for Dragon2 DM1 in particular, its a test flight. So the operators WANT lots of time to check out the vehicle, test all systems in orbit and make sure everything is working correctly before going anywhere near the station. So not only does it not need a quick rendezvous plan, it actually benefits from a nice slow and steady approach, so you can make sure everything is safe, since its a test flight.

Once Dragon2 is operational and doing crew flights, we might start seeing quick rendezvous approaches from SpaceX too, if NASA, their customer, is interested in that. It's really not a difficult thing for the launch vehicle and more a question of meticulous mission planning to shave a few hours of orbital travel time. It's really a question of priorities. Is it necessary to get the astronauts to station in the shortest time? Or is there more use in having additional time for acclimatization and getting used to zero G, (and having more schedule freedom for when to launch)

[refsmmat]

So can anybody work out the preliminary entry ground track next week? Because it's going to be nighttime and [if descending node] will cross populated areas of North America. The much bigger shuttles made SPECTACULAR entry fireballs across the US [I saw four or five, and even when it was forty mile up we could hear the MUCH later sonic boom ['thud' would better describe it].  And numerous witnesses reported the 'electrophonic sound' phenomenon caused by radio bursts from the plasma tail exciting materials in the earwitness vicinity, the old real-time audio bolide effect that baffled scientists for centuries.  http://www.jamesoberg.com/96mar-sts72_entry.pdf

It could be interesting viewing near a line that passes through Kansas City and Huntsville. The Sun will probably be up, but that doesn't mean don't look...  it means we don't know.

[JimO]

….. If I was able to ask a question I would like to know why SpaceX takes 27 hours to rendezvous with the ISS and the Russians take only 4 hours.

As CorvusCorax said.....

The quicker rendezvous isn't a matter of vehicle speed, it's a matter of target position along its orbit.

The dominant factor in a launch window is the plane of the target's orbit. You gotta go when you're able to go into that plane.

When you get into orbit, the next question is how far ahead of you is the target? It could randomly be anywhere, from overhead to the far side of Earth to coming up behind you.

You catch up orbit by orbit by staying lower and faster -- say, with station at 240 miles and chaser at 140, you catch up about 1,000 miles per orbit. [10 X delta-H per 90-minute rev]

But the length of the full orbit is about 25,000 miles, so the target's lead over the chaser can be somewhere between zero and that number. Whatever it is, you have to catch up and then rise to a higher docking orbit where the catch-up rate is a lot slower. 

The rapid rendezvous requires the target to literally fly into the hunter's gunsight, and happen to be in a very narrow range interval just ahead of the chaser at launch. That requires active thrusting by the station in the days before launch. This is complex, fuel costly, and brittle in that after several launch days are missed, the target can drift forward or back and go beyond the narrow permissable 'lead' range. And it has to be adjusted again.

For the first launch of a new vehicle, taking the trouble [and paying the cost]  to set up the only-temporary rapid rendezvous mutual alignment -- with the odds of launch scrubs -- probably isn't very attractive.

[jak Kennedy]

Something strange that Elon said in the post conference, to I believe his second question, while talking about Dragon 2 he said “Hardly a part in common with Dragon 1 which in retrospect will probably change”
Not sure what to make of that. Any thoughts or did I just read his reply incorrectly?

[M.E.T.]

Something strange that Elon said in the post conference, to I believe his second question, while talking about Dragon 2 he said “Hardly a part in common with Dragon 1 which in retrospect will probably change”
Not sure what to make of that. Any thoughts or did I just read his reply incorrectly?

Since Dragon2 is unlikely to change much given the strict certification process involved I assumed that meant that Dragon1 would be updated to have more commonality with Dragon2.

[groundbound]

Something strange that Elon said in the post conference, to I believe his second question, while talking about Dragon 2 he said “Hardly a part in common with Dragon 1 which in retrospect will probably change”
Not sure what to make of that. Any thoughts or did I just read his reply incorrectly?

Since Dragon2 is unlikely to change much given the strict certification process involved I assumed that meant that Dragon1 would be updated to have more commonality with Dragon2.

Isn't Dragon 1 in the process of being phased out?

[envy887]

Something strange that Elon said in the post conference, to I believe his second question, while talking about Dragon 2 he said “Hardly a part in common with Dragon 1 which in retrospect will probably change”
Not sure what to make of that. Any thoughts or did I just read his reply incorrectly?

Since Dragon2 is unlikely to change much given the strict certification process involved I assumed that meant that Dragon1 would be updated to have more commonality with Dragon2.

Isn't Dragon 1 in the process of being phased out?

Maybe they are going to use some Dragon 2 parts on upcoming Dragon 1 cargo flights.

[cppetrie]

I think he meant that if they were to do the development process over again they would have kept more commonality.

[deruch]

Broadcast of the view inside the cabin seemed to have some transmission issues. But it did look like the “zero gee indicator” earth plushie did start to float away after dragon separation.

But it looked like it didn’t start floating until separation?  If so, why didn’t it start floating as soon as SECO?

Even after the MVac shuts down, there is still some minor residual thrusting due to, I believe, minor ACS thrusting or LOX venting.  Maybe this allows them to prevent sloshing of residual propellants affecting the stack attitude?  Then once that ends, a brief period of quiescence is soon followed by Dragon separation.  The separation event includes some sort of spring or minor pushing mechanism which would also act to settle/re-settle the zero-G plushy.  Result being that, with the limited video/transmission capabilities shown during the webcast, it appears like the indicator only starts to float after separation.

[deruch]

Thankyou for posting this as I did not stay up to watch it live. However I am generally disappointed on the low quality questions in these briefing. More than 75% are Elon, how do you feel about.... all general emotional questions. I want to see answers to technical questions, the best one was about the grid hydraulic pump failure. If I was able to ask a question I would like to know why SpaceX takes 27 hours to rendezvous with the ISS and the Russians take only 4 hours.

To rendezvous with an orbiting spacecraft - such as the station - you need to wait until the earth is turning so your launch-pad is exactly aligned with the orbital plane - while the earth constantly rotates. This means, unless you are capable of doing very expensive high deltaV plane-change manouvers, you end up with an instantaneous launch window.

Now the problem is, that you end up in that exact perfect spot only once every 24 hours, as the earth rotates....

Minor correction, this alignment of ISS/target and launch site actually happens twice every 24 hours.  On both the ascending and descending tracks.  But due to the nature of range/launch safety constraints and the allowable launch azimuths from a given launch site, you may end up being limited to only one of those in practice.  For launches from KSC/CCAFS to the ISS, SpaceX and others are limited to only launching into the ascending track (northeast).  Launching into the descending track (southeast) would result in overflying landmasses/populations which would violate the allowed safety limits.