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[20200422_200816 UTC: Update: Launch was successful. The first-stage booster functioned nominally and successfully landed on a drone ship. The second stage successfully deployed the satellites at an altitude of approximately 250 km. The satellites will use on-board ion thrusters to raise their orbits up to a planned 550 km altitude. No word on this flight's fairing recovery attempt.--martyb]
SpaceX returns to the launch pad, and there are a few things to watch for:
SpaceX has targeted Wednesday afternoon for the next launch of its Falcon 9 rocket from a pad at Kennedy Space Center. This mission will launch the sixth batch of operational Starlink satellites, bringing the company closer to offering initial broadband Internet access to North America.
However, the Starlink-6 launch—set for
3:37pm ET (19:37 UTC)[*]—is notable for reasons beyond the simple extension of the company's Starlink network.[...] SpaceX has gotten pretty darn good at landing first stages back on Earth, as they have now done it 50 times. However, the company failed to successfully land the first stage on an autonomous drone ship the last two times it attempted to do so.
On February 17, after the Starlink-4 launch, the first stage received incorrect data about wind conditions near the landing location and missed the drone ship. Then, on March 18, one of the rocket's nine Merlin 1D engines failed during launch, and although the Starlink-5 satellites made orbit, this precluded a fully controlled return of the first stage.
[...] It is notable that SpaceX pushed up this week's launch from Thursday to Wednesday, citing a "more favorable weather forecast for launch and landing." Launch conditions on Wednesday are more favorable (90-percent chance of "go" weather) than Thursday, but seas, too, should be considerably less choppy in the landing zone offshore. This increases the chance of success.
[*] Rescheduled: As of 09:56 this Wednesday morning, this tweet states: "New T-0 of 3:30 p.m. EDT, 19:30 UTC, for today's launch of Starlink". For further updates, keep an eye on SpaceX's twitter fed.
Live stream on YouTube to start 10 minutes before liftoff.
I remember SpaceX's first successful landing and how amazing it was. Now they have succeeded 50(!) times and it has become so 'commonplace' we are surprised when they do not succeed in landing a booster!
(Score: 2) by deimtee on Thursday April 23 2020, @08:39AM (3 children)
That's very impressive on its own. With 10 seconds to MECO they analysed and compensated for an engine failure.
If you cough while drinking cheap red wine it really cleans out your sinuses.
(Score: 2) by takyon on Thursday April 23 2020, @11:47AM (2 children)
Not sure if you are referring to humans. The computer(s) in the rocket did the adjustment automatically.
It's arguably not a very complex operation. The top priority is getting the payload to its destination. Booster recovery is a secondary objective. Maybe third if you count safety of the booster handling. Knocking out 1/9 engines reduces thrust to about 89%. So the rocket burned some/most of the extra fuel that would have ideally been saved for a booster landing.
https://www.teslarati.com/spacex-falcon-9-booster-lost-successful-starlink-launch/ [teslarati.com]
https://www.youtube.com/watch?v=rmrSx2OuO84 [youtube.com]
It actually came relatively close to the drone barge, just way too fast.
https://en.wikipedia.org/wiki/Falcon_9_booster_B1048 [wikipedia.org]
The engine failure was probably due to it being fifth-flown hardware, but no explanation has been given yet AFAIK. The booster had undergone a successful static fire test, but the rocket's computer aborted the first launch attempt in the literal last second:
SpaceX rocket performs first last-second launch abort in years, delaying Starlink mission [teslarati.com]
The recent Starlink missions push Falcon 9 to its limits, carrying the most massive payloads flown by the company at 15,600 kg per batch. That leaves less fuel for landing than many other missions. They are going to fly these F9 boosters until death, unless they switch to Starship. Maybe one will reach 10 successful flights.
[SIG] 10/28/2017: Soylent Upgrade v14 [soylentnews.org]
(Score: 2) by deimtee on Thursday April 23 2020, @06:25PM (1 child)
I am (rather distantly) acquainted with an actual lockheed-martin rocket scientist. Everything else about Spacex was between "yeah, o.k." to "oh, well done there!". But he just couldn't believe their controls engineering.
When he saw the video of the first grasshopper, he was very impressed with the hovering, but when it landed on its rockets, on the pad, he was flabbergasted. I think he would have been willing to believe the video was faked ahead of them being able to actually do that. (I think it was this one, https://www.youtube.com/watch?v=a5jHvF2t2eI [youtube.com] )
Their system correctly analysed a major failure and fully compensated for it on its own, placing the mission success ahead of successful recovery. Compare that to MCAS where a single faulty sensor meant the plane dived into the ground, even with two pilots struggling to prevent it. Maybe Boeing should pay Spacex to do their QA.
If you cough while drinking cheap red wine it really cleans out your sinuses.
(Score: 1) by khallow on Friday April 24 2020, @01:07AM