I would not be surprised if reducing ASDS recovery time is the prime driver here and we start seeing similar optimizations also in other launches - any spare first stage perf goes towards reducing the downrange distance even when there is not enough perf to do a land landing.
There is no spare performance on Starlink launches. It is only external launches that have margins for contingency.
The boostback is necessary to reduce landing weight, as the F9 does not dump fuel like as airliner. Reducing ASDS travel time is just an extra benefit. This is common on CRS launches.
I don't think this is true
I would not be surprised if reducing ASDS recovery time is the prime driver here and we start seeing similar optimizations also in other launches - any spare first stage perf goes towards reducing the downrange distance even when there is not enough perf to do a land landing.
There is no spare performance on Starlink launches. It is only external launches that have margins for contingency.
The boostback is necessary to reduce landing weight, as the F9 does not dump fuel like as airliner. Reducing ASDS travel time is just an extra benefit. This is common on CRS launches.
I don't think this is true
Demonstrably false since Starlink 5 had an engine out but still made orbit (and only failed landing due to another engine anomaly).
More photos of the Falcon 9 B1067 and the Cargo Dragon C209
I would not be surprised if reducing ASDS recovery time is the prime driver here and we start seeing similar optimizations also in other launches - any spare first stage perf goes towards reducing the downrange distance even when there is not enough perf to do a land landing.
There is no spare performance on Starlink launches. It is only external launches that have margins for contingency.
The boostback is necessary to reduce landing weight, as the F9 does not dump fuel like as airliner. Reducing ASDS travel time is just an extra benefit. This is common on CRS launches.
1. There is no spare performance on Starlink launches.
The margins are small, and Starlink 5 would have eaten into them when an engine failed. We don't know for sure if there would still have been sufficient propellant for landing.
2. It is only external launches that have margins for contingency.
I think it is fair to say CRS2 missions have more margin than Starlink, the payload is a few tonnes less to comparable orbits.
3. The boostback is necessary to reduce landing weight, as the F9 does not dump fuel like as airliner.
Actually there is a choice. The necessary reduction of energy can be spread across the boostback and entry burns, or have a longer entry burn. I suspect they wanted to try the simpler profile first on SPX21.
4. Reducing ASDS travel time is just an extra benefit. This is common on CRS launches.
Yes to both.
Personally, I think they're doing the partial boostback burn to land ~300 kilometers downrange because they want to bring the drone ship back to port quicker than the typical ~600 kilometer route.
Just a guess.
Demonstrably false since Starlink 5 had an engine out but still made orbit (and only failed landing due to another engine anomaly).
I was speaking specifically to fuel margins. Slightly increasing thrust from the additional engines to make up for the lost engine doesn’t use up significantly more fuel.
Demonstrably false since Starlink 5 had an engine out but still made orbit (and only failed landing due to another engine anomaly).
I was speaking specifically to fuel margins. Slightly increasing thrust from the additional engines to make up for the lost engine doesn’t use up significantly more fuel.
Starlink 5 more than made up for the loss of an engine, by burning for longer, but more importantly, this changed the ballistic trajectory after MECO. Convergence on the droneship would then have required more propellant than normal.
https://www.nasaspaceflight.com/2019/05/first-starlink-mission-heaviest-payload-launch-spacex/Mr. Musk also noted that the 60 starlink satellite count for this mission is not the maximum number of Starlinks SpaceX could have packed on board the Falcon 9. If SpaceX were to sacrifice recovery and reuse of the first stage of the Falcon 9, they could have added more Starlinks into the payload fairing.
Pretty close to maxing out the capabilities of F9 on a Starlink launch. But I think we can all agree there is significantly more fuel margin on a CRS launch than a Starlink launch.
We can agree that there is more fuel margin on a CRS launch than a Starlink launch, but you claimed that they have to do a boostback because of the difference. CRS-21 had a lighter payload and landed 300km farther downrange. There are many ways to manage the propellant load.
Prelaunch conference has started:
...
Prelaunch conference archived at
https://youtube.com/watch?v=SvvGVq2dwn0 (Length: 27:54)
(Via "AmericaSpace" YouTube channel; with ads -- please PM me if you have a better source.)
Exact launch times:
24:13Q [submitted by Stephen Clark – Spaceflight Now]: What is the exact time with seconds for Thursday? What are the launch opportunities beyond Thursday and Friday?
A [Sarah Walker - Director, Dragon Mission Management - SpaceX]: To the second, it is 1:29:15 p.m. EDT [17:29:15 UTC], and the backup is 1:03:33 p.m. EDT [17:03:33 UTC]. We will have the 3rd and the 4th. If we don't launch either of those opportunities, we'll stand down for a day and refresh a large amount of NASA cargo -- science samples -- and then we have another two opportunities the following pair ... 6th and 7th would be the next opportunity.
Some other Q&A highlights:
24:55Q [followup by Stephen Clark]: With the Sirius XM launch this weekend [currently expected for 12:25-2:26 a.m. EDT (04:25-06:26 UTC), Sunday, June 6], could you do two launches in one day if necessary?
A [Sarah Walker]: Yes. So we've definitely looked at all the various constraints that affect how close in time, even down to hours, we could launch two missions, and I think we've come pretty close on previous missions to this. Right now, if we launch on the 3rd or the 4th they won't be very close to one another, but certainly if we go on the 6th they will be within 24 hours.
(That seemed to be an affirmative, but the initial "Yes" could have simply been affirmation of the question followed by a non-answer.)
23:17Q: What will be the next mission for this new first-stage booster?
A [Sarah Walker]: It's actually staying in the family for a little while, so right now it's allocated to the Crew-3 mission, the next crew mission coming up in the fall.
23:32Q: How much time will Node 2 Forward be available for OFT-2, and is the schedule on OFT-2 dependent on the Russian MLM?
A [Joel Montalbano- ISS Program Manager - NASA]: There's really no dependence between the Node 2 Forward and MLM. We like to make sure we don't have dynamic activities on back-to-back days, and we like a few days in between those. As far as duration, it will be a short mission on the order of four to eight days. It could be a little longer if we need to set up the right phasing for landing, but its a short mission.
Earlier:
3:13We have a launch time of 1:29 p.m. Eastern Time on Thursday. That sets us up for a docking early Saturday morning about 5 a.m. Eastern Time, and that will put us on the Node 2 Zenith port, so the docking port that's on top of Space Station. This mission will return in early July with approximately 4200 pounds of pressurized cargo.
Another busy month in July. The Russians are launching a new module called the Multipurpose Laboratory Module, or MLM, to the International Space Station, that's scheduled to launch on July 15th with the docking on July 23rd. We'll also have a port relocation where we'll put the crew members in the Crew Dragon and we'll move the vehicle from the Note 2 Forward port to the Node 2 Zenith port. That opens up the Forward port for the Boeing unmanned test mission scheduled for July 30.
Fast forward into August, you have a Northrop Grumman-16 mission, another SpaceX mission [CRS-23, currently expected on 18 August], so again, we continue to be extremely busy on the International Space Station.
(I assume a second port relocation will occur between OTF-2 and SpX/CRS-23.)
16:05We'll have an early morning docking, about 5:13 a.m. on Saturday morning, Eastern time.
And then lastly, I wanted to show you an amazing video -- if you could cue that up. This is actually footage from CRS-21, the last cargo mission that went to Space Station. This is what the ISS looks like from Dragon's eyes as it performs a series of maneuvers to gradually catch up, rendezvous, and eventually dock with International Space Station.
The very cool, one-minute video starts at
16:17.
(Hey SpaceX! We would love to see this with another 10 seconds, taking us all the way through docking.)
Finally:
27:18Again, liftoff is scheduled for tomorrow, June 3, at 1:29 p.m. Eastern Time. Launch coverage will begin 30 minutes prior, at about 1 p.m. Eastern Time and then will end about 20 minutes after that, but we will pick back coverage up again on Saturday, June 5, at 3:30 a.m. for docking to the Space Station around 5 a.m.
Weather 60% Favorable for Today’s Launch
Danielle Sempsrott Posted on June 3, 2021
NASA and SpaceX are targeting 1:29 p.m. EDT today, June 3, for SpaceX’s 22nd cargo resupply launch to the International Space Station. The company’s Falcon 9 rocket and uncrewed Dragon spacecraft will lift off from Launch Complex 39A at NASA’s Kennedy Space Center in Florida.
Weather officials with Cape Canaveral Space Force Station’s 45th Weather Squadron continue to predict a 60% chance of favorable weather conditions for today’s launch, with the cumulus cloud rule and flight through precipitation serving as the primary weather concerns.
Dragon will deliver critical science and research investigations, crew supplies, and hardware to the space station. Upon Dragon’s arrival – slated for Saturday, June 5 – NASA astronauts Shane Kimbrough and Megan McArthur will monitor operations while the spacecraft autonomously docks to the orbiting laboratory’s Harmony module.
Beginning at 1 p.m., join us here on the blog for live coverage, and follow along on NASA TV or the agency’s website for the live launch broadcast.
https://blogs.nasa.gov/spacexcrs22/2021/06/03/weather-60-favorable-for-todays-launch/