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  [Discuss] SpaceX Crew Dragon Demo-2 (Page 4)

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Author Topic:   [Discuss] SpaceX Crew Dragon Demo-2
Robert Pearlman
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posted 05-27-2020 01:57 PM     Click Here to See the Profile for Robert Pearlman   Click Here to Email Robert Pearlman     Edit/Delete Message   Reply w/Quote
All of the major U.S. networks (ABC, NBC, CBS and FOX) have said they will be breaking into their normal programming to broadcast the launch.

Blackarrow
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posted 05-27-2020 02:50 PM     Click Here to See the Profile for Blackarrow     Edit/Delete Message   Reply w/Quote
quote:
Originally posted by Robert Pearlman:
If it does not launch at that time, the attempt will be scrubbed for the day.
So noted, but it would help if SpaceX would resolve the ambiguity in their countdown information.

Philip
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posted 05-27-2020 02:59 PM     Click Here to See the Profile for Philip   Click Here to Email Philip     Edit/Delete Message   Reply w/Quote
Did the crew pre-breath pure oxygen? I guess not...

Robert Pearlman
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posted 05-27-2020 03:17 PM     Click Here to See the Profile for Robert Pearlman   Click Here to Email Robert Pearlman     Edit/Delete Message   Reply w/Quote
Scrub! Due to continuing violations of several different weather rules that were not expected to clear in time, today's (May 27) attempt at launching the Demo-2 mission has been scrubbed.

"It was a good effort by the teams," said Hurley.

The next launch opportunity is on Saturday, May 30 at 3:22 p.m. EDT.

David C
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posted 05-27-2020 03:22 PM     Click Here to See the Profile for David C     Edit/Delete Message   Reply w/Quote
Ah, it wouldn't really be manned spaceflight without at least one scrub.

quote:
Originally posted by Philip:
Did the crew pre-breath pure oxygen? I guess not...

No need.

Delta7
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posted 05-27-2020 03:31 PM     Click Here to See the Profile for Delta7   Click Here to Email Delta7     Edit/Delete Message   Reply w/Quote
Is the Pope Catholic? Does a bear you-know-what in the woods? Do space launches get scrubbed? But of course! We are definitely back in the human space launch business!

moorouge
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posted 05-27-2020 04:25 PM     Click Here to See the Profile for moorouge   Click Here to Email moorouge     Edit/Delete Message   Reply w/Quote
I gather that this mission required a launch at a specific time and that the countdown had no provision for holds because of weather problems. All previous missions had launch windows so why is this one different?

Robert Pearlman
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posted 05-27-2020 05:05 PM     Click Here to See the Profile for Robert Pearlman   Click Here to Email Robert Pearlman     Edit/Delete Message   Reply w/Quote
All launches to the space station by SpaceX's Falcon 9, Russia's Soyuz and Japan's H-IIB have instantaneous launch windows. Quoting Wikipedia:
Achieving the correct orbit requires the Right Ascension of the Ascending Node (RAAN). RAAN is set by varying a launch time, waiting for Earth to rotate until it is in the correct position. For missions with very specific orbits, like rendezvousing with the International Space Station the launch window may be a single moment in time, known as an instantaneous launch window.

Trajectories are programmed into the vehicle prior to launch. The launch vehicle will have a target, and the guidance system will alter the steering commands to attempt to get to the final end state. At least one variable (apogee, perigee, inclination, etc.) must be left free to alter the values of the others, otherwise the dynamics would be over-constrained.

An instantaneous launch window allows the RAAN be the uncontrolled variable. While some spacecraft such as the Centaur upper stage can steer and adjust its RAAN after launch, choosing an instantaneous launch window allows the RAAN to be pre-determined for the spacecraft's guidance system.

MOL
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posted 05-27-2020 05:18 PM     Click Here to See the Profile for MOL   Click Here to Email MOL     Edit/Delete Message   Reply w/Quote
I guess a better question is why didn't the space shuttle require an instantaneous window? I recall 5-10 minute windows for shuttle flights to the ISS.

thisismills
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posted 05-27-2020 06:24 PM     Click Here to See the Profile for thisismills   Click Here to Email thisismills     Edit/Delete Message   Reply w/Quote
Nice to read the details on the launch rule process.

Joking around that had it been a different Bob and Doug, they would have still took off, eh? Back-bacon and beer for breakfast!

Happy that the decision tree is in place to allow these calls to be made no matter how many people are eagerly watching. The teams should be proud of their all-up run today, good practice.

Excited for their next attempt.

Robert Pearlman
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posted 05-27-2020 07:23 PM     Click Here to See the Profile for Robert Pearlman   Click Here to Email Robert Pearlman     Edit/Delete Message   Reply w/Quote
quote:
Originally posted by MOL:
...why didn't the space shuttle require an instantaneous window?
Like the Centaur (as mentioned in the Wikipedia citation) and Northrop Grumman's Antares rocket, the shuttle had the energy to steer into the right place after launch.

CMD_OVRD
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posted 05-27-2020 08:44 PM     Click Here to See the Profile for CMD_OVRD   Click Here to Email CMD_OVRD     Edit/Delete Message   Reply w/Quote
quote:
Originally posted by GACspaceguy:
I see a watch on Bob, what are they using?
Both astronauts are wearing Omega X-33 Gen 2 wristwatches. Since NASA has been issuing the X-33 Gen 3 to its recent ISS crews, I am assuming that these watches were the same ones that Bob and Doug wore on their previous shuttle flights.

I've seen photos of current ISS commander Chris Cassidy wearing a X-33 Gen 2 as well. Again, most likely from his previous flights.

GACspaceguy
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posted 05-28-2020 05:21 AM     Click Here to See the Profile for GACspaceguy   Click Here to Email GACspaceguy     Edit/Delete Message   Reply w/Quote
quote:
Originally posted by Robert Pearlman:
The next launch opportunity is on Saturday, May 30 at 3:22 p.m. EDT.
Just looking at the Titusville forecast (and yes this is Florida in the afternoon and anything can change) the peak of thunderstorm probability is the 3-5 PM EDT. What would be the following launch attempt date? After Saturday do they have to stand down for vehicle replenishment?

Robert Pearlman
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posted 05-28-2020 07:30 AM     Click Here to See the Profile for Robert Pearlman   Click Here to Email Robert Pearlman     Edit/Delete Message   Reply w/Quote
The 45th Space Wing Weather Squadron L-3 forecast for a launch on May 30 predicts a 60 percent chance of violating weather constraints, with the primary concerns being flight through precipitation, the anvil cloud rule and the cumulus cloud rule.

The forecast remains the same for the next opportunity on Sunday, May 31 at 3:00 p.m. EDT. (SpaceX has not announced dates beyond that.)

Rolf
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posted 05-28-2020 07:33 AM     Click Here to See the Profile for Rolf   Click Here to Email Rolf     Edit/Delete Message   Reply w/Quote
I saw astronaut Zena Cardman photographing around the Tesla, but who is the other astronaut in this photo?

Delta7
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posted 05-28-2020 08:04 AM     Click Here to See the Profile for Delta7   Click Here to Email Delta7     Edit/Delete Message   Reply w/Quote
I think that's Drew Feustel. He posted on social media that he was at the Cape to support the mission.

BA002
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posted 05-28-2020 08:53 AM     Click Here to See the Profile for BA002   Click Here to Email BA002     Edit/Delete Message   Reply w/Quote
Is this instantaneous launch window specific to Crew Dragon and if so why?
I seem to recall that the shuttle had some leeway? And Soyuz?

Astro Rich
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posted 05-28-2020 09:15 AM     Click Here to See the Profile for Astro Rich   Click Here to Email Astro Rich     Edit/Delete Message   Reply w/Quote
The shuttle had different performance margins that allowed for a little longer launch window be it only a few minutes, The Soyuz is like the Dragon and has an instantaneous launch window which makes it a little more tricky with the afternoon thunderstorms that are common in the summer in Florida.

mercsim
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posted 05-28-2020 09:16 AM     Click Here to See the Profile for mercsim   Click Here to Email mercsim     Edit/Delete Message   Reply w/Quote
They talked about it during the coverage around 30 minutes before scheduled liftoff. The performance is based on the fuels having specific properties at liftoff.

Once they start fueling, the liftoff time is pretty much set. If they hold the fuel warms and changes properties. They just didn't design holding into the system. It probably saved weight on extra valves, fuel, plumbing, etc.

I'm sure one of our expert Googlers can chime in and add more or correct me. They only briefly mentioned it when the announcers were talking about the possible weather scrub. There is obviously some margin and ability to modify trajectory on the fly in the event of premature engine shutdown. After all, it actually is rocket science.

Robert Pearlman
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posted 05-28-2020 11:11 AM     Click Here to See the Profile for Robert Pearlman   Click Here to Email Robert Pearlman     Edit/Delete Message   Reply w/Quote
While there is a limit of time before the cryogenic propellant boils off, it is not what drives the instantaneous launch window. There is no difference between how Falcon 9 is fueled for a Crew Dragon launch versus a satellite launch, the latter having a longer window.

Aeropix
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posted 05-28-2020 11:15 AM     Click Here to See the Profile for Aeropix   Click Here to Email Aeropix     Edit/Delete Message   Reply w/Quote
If it was mission critical to offer a launch window rather than instantaneous, couldn't SpaceX discard the booster rather than recovering it, thereby offering the return fuel for the maneuvering required to extend the launch window?

Would the guidance system be flexible enough to handle such a change? Perhaps "if launch on-time then use trajectory "A" and recover booster; else if launch late then use fuel for modified trajectory "B', "C", "D" etc. to extend launch window"?

Paul78zephyr
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posted 05-28-2020 11:16 AM     Click Here to See the Profile for Paul78zephyr     Edit/Delete Message   Reply w/Quote
quote:
Originally posted by Robert Pearlman:
The 45th Space Wing Weather Squadron L-3 forecast for a launch on May 30 predicts a 60 percent chance of violating weather constraints...
Could you discuss under what circumstances that they wouldn't even begin the crew loading process? Would the chance of violating weather constraints have to be 100 percent?

Rolf
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posted 05-28-2020 11:33 AM     Click Here to See the Profile for Rolf   Click Here to Email Rolf     Edit/Delete Message   Reply w/Quote
quote:
Originally posted by Delta7:
I think that's Drew Feustel.
Thank you. I also think I see his STS-125 and ISS-56 patches now.

Robert Pearlman
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posted 05-28-2020 12:05 PM     Click Here to See the Profile for Robert Pearlman   Click Here to Email Robert Pearlman     Edit/Delete Message   Reply w/Quote
quote:
Originally posted by Paul78zephyr:
...under what circumstances that they wouldn't even begin the crew loading process?
If the weather outlook was such that there was no realistic chance of meeting the requirements to load propellants, they would probably stand down before boarding the crew. Likewise, if there are a significant and persistent weather concern for the abort sites (which is not reflected in the 45th Space Wing forecast), that could also lead to a decision to scrub before sending the crew to the launchpad.

In general though, a high probability of poor weather is not necessarily a reason to scrub early. The shuttle launched when the forecast was 90 percent no go. If the concern is only the weather at the launch site, then there is always the possibility of a brief break in the clouds, rain or winds at T-0.

damnyankee36
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posted 05-28-2020 01:13 PM     Click Here to See the Profile for damnyankee36   Click Here to Email damnyankee36     Edit/Delete Message   Reply w/Quote
What ever happened to the announcement of the name the crew was giving their spacecraft? Didn't hear it mentioned during launch day coverage nor elsewhere in the news.

Robert Pearlman
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posted 05-28-2020 01:25 PM     Click Here to See the Profile for Robert Pearlman   Click Here to Email Robert Pearlman     Edit/Delete Message   Reply w/Quote
Either we did not get far enough along in the countdown or the crew was waiting until they reached orbit to announce the name.

Hurley and Behnken have a live TV broadcast from on aboard the Crew Dragon about three hours after their launch.

BMckay
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posted 05-28-2020 04:14 PM     Click Here to See the Profile for BMckay   Click Here to Email BMckay     Edit/Delete Message   Reply w/Quote
If you are at the Kennedy Space Center Visitor Complex on Saturday, what part of the open park is the best place to view the launch? The bleachers near the rocket garden or someplace else?

mercsim
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posted 05-28-2020 06:43 PM     Click Here to See the Profile for mercsim   Click Here to Email mercsim     Edit/Delete Message   Reply w/Quote
quote:
Originally posted by Robert Pearlman:
There is no difference between how Falcon 9 is fueled for a Crew Dragon launch versus a satellite launch...
I didn't say there was a difference in the way it was fueled. But you are correct, its fueled just like other satellite launchers, and your car. They plug a hose in and turn it on.

I didn't say the fuel boiled off. I said it it was designed to liftoff with specific properties. That was what the SpaceX employee said during the coverage.

Spaceflyer
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posted 05-29-2020 02:27 AM     Click Here to See the Profile for Spaceflyer   Click Here to Email Spaceflyer     Edit/Delete Message   Reply w/Quote
quote:
Originally posted by Rolf:
I also think I see his STS-125 and ISS-56 patches now.
That's for sure Drew Feustel at the walkout. On his right arm is his STS-125 patch and the second version of his Soyuz MS-08 patch and not the ISS-56 patch. His ISS-55 and ISS-56 patches are on the front of his flight suit.

Rolf
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posted 05-29-2020 04:17 AM     Click Here to See the Profile for Rolf   Click Here to Email Rolf     Edit/Delete Message   Reply w/Quote
Thank you for the correction. More information about this Soyuz MS-08 patch.

mercsim
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posted 05-29-2020 10:01 AM     Click Here to See the Profile for mercsim   Click Here to Email mercsim     Edit/Delete Message   Reply w/Quote
I have to comment on the launch. I'M SUPER EXCITED! As a retired Aerospace Engineer and lifelong space enthusiast, this is a BIG deal.

I detect a bit of excitement in Robert's postings but you can tell he is trying to keep the cool, journalistic demeanor. I think the forum is a bit reserved too. I was glued to the computer Wednesday and can't wait until tomorrow. I'll have to go watch Space Force to help pass the time.

Who else is excited?

Kite
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posted 05-29-2020 10:41 AM     Click Here to See the Profile for Kite     Edit/Delete Message   Reply w/Quote
I am. Really looking forward to the Americans returning to space in their own transport. Exciting times ahead.

David C
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posted 05-29-2020 01:01 PM     Click Here to See the Profile for David C     Edit/Delete Message   Reply w/Quote
I’m looking forward to seeing the first absolutely clean sheet manned spacecraft fly since the shuttle.

I know there's been several Soyuz upgrades, but that's far from being the same thing. Even CST-100 doesn’t seem as exciting, sitting on top of Atlas V. I know Atlas V has nothing in common with the Atlas of the Mercury days, but somehow just having the name makes it seem less exciting than this beast.

ManInSpace
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posted 05-29-2020 01:23 PM     Click Here to See the Profile for ManInSpace     Edit/Delete Message   Reply w/Quote
quote:
Originally posted by mercsim:
Who else is excited?
Count me in!

Robert Pearlman
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posted 05-30-2020 07:55 AM     Click Here to See the Profile for Robert Pearlman   Click Here to Email Robert Pearlman     Edit/Delete Message   Reply w/Quote
From SpaceX (via Twitter):
All systems go for Crew Dragon's test flight with NASA astronauts Bob Behnken and Doug Hurley. Teams are keeping an eye on weather.

NASA live video

Tune in starting at 11 a.m. EDT as NASA and SpaceX provide joint, live coverage from launch to arrival at the space station. Teams are targeting 3:22 p.m. EDT for the launch of the SpaceX Crew Dragon spacecraft atop a Falcon 9 rocket from historic Launch Complex 39A at NASA's Kennedy Space Center in Florida.

Robert Pearlman
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posted 05-30-2020 09:51 AM     Click Here to See the Profile for Robert Pearlman   Click Here to Email Robert Pearlman     Edit/Delete Message   Reply w/Quote
Timeline for today's (May 30) launch attempt:

Aeropix
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posted 05-30-2020 11:45 AM     Click Here to See the Profile for Aeropix   Click Here to Email Aeropix     Edit/Delete Message   Reply w/Quote
Dragon capacity four or seven crew?

Watching the launch prep, I notice that the SpaceX commentator said the maximum capacity of Dragon was four crew, but I thought it was designed for seven crew? Are the fifth, sixth and seventh seats for contingency only or did they change the specs? Must be nice and roomy if only four people fly on a seven-crew vehicle. Maybe that's how they got to install a toilet after all?

Robert Pearlman
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posted 05-30-2020 12:03 PM     Click Here to See the Profile for Robert Pearlman   Click Here to Email Robert Pearlman     Edit/Delete Message   Reply w/Quote
Crew Dragon has the capability of launching seven people, but for NASA flights, the spacecraft will be configured with only four seats. The mass (and some of the volume) gained by omitting the three seats is being used to fly cargo to the space station.

(The toilet is mounted on the inside wall above the hatch, and so can be present on all flights, regardless of the number of seats, per SpaceX.)

Robert Pearlman
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posted 05-30-2020 01:34 PM     Click Here to See the Profile for Robert Pearlman   Click Here to Email Robert Pearlman     Edit/Delete Message   Reply w/Quote
Weather is now "go" for launch at this time (T-48 minutes).

Liftoff is scheduled for 3:22:45 p.m. EDT (1922 GMT).

Robert Pearlman
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posted 05-30-2020 02:24 PM     Click Here to See the Profile for Robert Pearlman   Click Here to Email Robert Pearlman     Edit/Delete Message   Reply w/Quote
Liftoff!
America has launched! And so rises a new era of American spaceflight and with it the ambitions of a new generation continuing the dream.


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