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Space Launches, Landings & Destinations v4


SpaceChampion

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Firstly, I want to give you a huge thank-you, SpaceChamp, for the incredible contribution you provide here. I read all your posts and watch the vidoes you link. I rely on your posts to keep me informed as to what's happening with rocket launches and space exploration. You make a massive contribution to this forum and I really appreciate it.

Secondly, I have a question I'm curious about and you may be able to enlighten me. :) 

I'm just wondering why SpaceX seem to so often seem to return their main boosters to drone ships, rather than to the launch pads on land. Returning to a stable base on land would logically seem far simpler than trying to land on a drone ship that is rocking around in the ocean (and returning to the launch pad makes for a much cooler video :P). Is it simply that the trajectory of the rockets means that they can more easily return to earth in the ocean, rather than trying to "fly" themselves back to the launch site for landing?

Anyway... thanks again for all the updates you provide. I might not comment much (or at all), but I always read your posts and view the videos you link.

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1 hour ago, AndrewJ said:

I'm just wondering why SpaceX seem to so often seem to return their main boosters to drone ships, rather than to the launch pads on land. Returning to a stable base on land would logically seem far simpler than trying to land on a drone ship that is rocking around in the ocean (and returning to the launch pad makes for a much cooler video :P). Is it simply that the trajectory of the rockets means that they can more easily return to earth in the ocean, rather than trying to "fly" themselves back to the launch site for landing?

Glad you're enjoying it.  :-)

It all depends on what kind of orbit they need to achieve, how heavy the payload is, and how much fuel is left available for landing.  Every flight is unique, so is custom designed based on the capabilities of the rocket and requirements of the customer. 

They try to put the drone ship in a calm spot in the ocean so it is not bobbing around too much.  Landing back at the launch site takes more energy / propellants because it's not launching straight up, but going hundreds of kilometers out from the coast.  Getting to orbit is not just getting to that high an altitude, but moving very fast sideways so you can circle the globe at a velocity around Mach 25 - 30.

The landing furthest out was something like 320 km.  It's usually less than that.  They try to shorten it to make returning the drone ship to the coast take as little time as possible.  The first stage separates at around 80km high, going about Mach 10. 

Compare the two scenarios:
Flight to drone ship:   https://www.spacex.com/static/images/infographics/F9_AUTONOMOUS_DRONESHIP_DESKTOP.jpg

Flight to landing zone: https://www.spacex.com/static/images/infographics/F9_LANDING_ZONE_DESKTOP.jpg

Without wings, they can't use aerodynamics to fly the booster stage back, so they have to rely on the engines.

To get back to the landing zone, they do a flip and burn that takes the first stage even higher than the 80km.  So it's an extra burn that adds complexity, but it's the detriment on fuel use that makes it rare compares to how often they land on the drone ship.  The Falcon 9 has about 4% of it's total launch weight available for both payload and landing.  Landing might take 1.3% of that, so that means only 2.7% is available for the payload, putting an upper limit on how heavy a satellite they can launch, and how high an orbit it can go.  Going to the drone ship makes it possible to have  heavier payloads and higher final orbits.  I don't know the actual numbers, but it's relatively more fuel than that to land at the landing zone, not because of the landing itself, but because of that extra flip and burn to go higher with the booster stage.  So 1.3% + X% where X needs to be just enough to cancel and somewhat reverse the sideways motion of going Mach 10.

If they need the full 4% for the satellite, they'd just not land the first stage, fly it in expendable mode (without landing legs) and sinking it in the ocean.  They typically use old boosters for that, that have flown several times already.

 

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On 3/2/2022 at 4:08 PM, SpaceChampion said:

Yes, and unfortunately that means the next ExoMars rover Rosalind Franklin is kaput.  It's not just the ride to Mars that's the issue there, otherwise they could probably just go with an Ariane 5 or Falcon Heavy.  But the Russians were suppose to supply the landing craft Kazachok ("Little Cossack") to get it to the surface, as well as several science instruments.

The articles I read are a little confusing but it seems ExoMars was supposed to launch on a Proton rocket, not a Soyuz.  The Soyuz are launched from ESA's French Guiana site, and those are what are being discontinued.  So not launching on a Proton isn't explicitly announced yet, but ESA expects it.

Not sure about ESA but Germany has suspended all cooperation with Russia in science. That includes the eROSITA X-ray space telescope, which has been shut down.

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8 hours ago, Loge said:

Not sure about ESA but Germany has suspended all cooperation with Russia in science. That includes the eROSITA X-ray space telescope, which has been shut down.

It sucks when science suffers for our inability to maintain peace.

Fuck Putin.

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Progress towards making SpaceX launches carbon-neutral:

World’s Largest Hydrogen Plant Says It’s Going to Power SpaceX Launches

Quote

US startup company Green Hydrogen International announced plans for a a 60GW renewable H2 project that will be powered by wind and solar. It’ll also produce clean rocket fuel for SpaceX, which is helmed by billionaire Tesla CEO Elon Musk, according to a report published yesterday in Recharge.

“We see Hydrogen City becoming one of the largest H2 production centers in the world, supplying many different customers with 100% clean H2 fuel,” founder Brian Maxwell told the energy industry pub.

 

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  • 2 weeks later...
33 minutes ago, SpaceChampion said:

Very unusual to switch colours like that, but they're wearing the colours of the Ukrainian flag now.  Hope they don't disappear into a gulag when they get back.

 

Do Cosmonauts get to pick the color of their flight suits before launch or is that planned well in advance?

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6 minutes ago, Ser Scot A Ellison said:

Do Cosmonauts get to pick the color of their flight suits before launch or is that planned well in advance?

Someone must have changed it out at the last minute before it could be discovered, I think.  Usually packed a few months before.

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OneWeb has reached an agreement with SpaceX to launch its internet constellation satellites on Falcon 9 rockets beginning later this year, after Rosocosmos screwing them over.  Another win for the broomstick / trampoline.

With Falcon, OneWeb should be able to put two to three times the mass of sats as they would with Soyuz per launch.

 

Latest Starlink launch:

 

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Hopefully it won't be holding up SpaceX, as Musk said they now targetting May for the first orbital launch of Starship / Super Heavy.

Blue Origin intends to bid, but Dynetics seems like the better option.  They have reportedly made progress on making it 100% reusable.

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31 minutes ago, Corvinus85 said:

lol, has Bezos's head exploded yet?

haha, no this is extending the previous award for the option embedded in it for a 2nd flight of the SpaceX's HLS Starship.  The new competition for a 2nd lander announced earlier is specifically written to be for another company. 

It's possible that won't be Blue Origin either.  Dynetics looks like a better option now that it's cleared some of the mistakes in the previous bid.  The rush to get Artemis to the Moon in 2024 is no longer a driving factor, now that NASA has acknowledged they won't be ready for that (it was a poorly thought out Trump demand), so Dynetics had time to figure out how to make their 100% reusable and reduce the mass.

I doubt Blue Origin has learned from its mistakes.

 

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