SpaceX Tuesday...
Discussion
jingars said:
In the Scott Manley vid linked to (a couple of times) earlier he mentions half a dozen launches being required to fuel a single Lunar Starship.
Zubrin has posted that it would need 20 Starship tanker launches per Lunar Starship. whilst The Angry Astronaut is of the view that it will be somewhere between 9 and 13 tanker launches per trip.
All in low Earth orbit, which is pitched as a mitigating factor as any problems are encountered before heading off to the Moon.
That launch rate is going to need quite a fleet of boosters and associated launch and fuelling infrastructure - with contingency for RUDs.
Musk's goal is turnaround times measured in hours; if they can do it the fleet need not be so large.Zubrin has posted that it would need 20 Starship tanker launches per Lunar Starship. whilst The Angry Astronaut is of the view that it will be somewhere between 9 and 13 tanker launches per trip.
All in low Earth orbit, which is pitched as a mitigating factor as any problems are encountered before heading off to the Moon.
That launch rate is going to need quite a fleet of boosters and associated launch and fuelling infrastructure - with contingency for RUDs.
AJLintern said:
So is the lunar version of Starship just going to sit in orbit awaiting the next mission, and the astronauts transfer to a regular Starship or Dragon to get back to Earth...?
It will remain attached to the lunar gateway, in lunar orbit.The 'nauts will return on Orion.
Guessing they will need to send tankers to refuel it.
annodomini2 said:
It will remain attached to the lunar gateway, in lunar orbit.
The 'nauts will return on Orion.
Guessing they will need to send tankers to refuel it.
How many tankers would you need to refuel a ship in lunar orbit (LLO or NRHO, I doubt it makes much difference when going that far!)? If it's a double-digit number of tankers to refuel in LEO it feels like you'd be looking at sending up several tankers to LEO (*), refuelling each of them and then sending them to the moon with a buddy-style refuelling system (like the Black Buck missions). Presumably the tankers would need to keep a fair amount of fuel back for themselves to get back from the moon and slow down when they reached the Earth (plus landing!). The 'nauts will return on Orion.
Guessing they will need to send tankers to refuel it.
(*) e.g. Three tankers get fuelled up in LEO. Two (A, B) perform a TLI for free-return trajectory to the moon. En-route B offloads fuel to A.
The "Full" tanker A performs an orbital insertion burn and docks to the lunar starship, offloads its fuel.
Tanker B continues on the free return trajectory back to earth orbit and performs EDL.
The third tanker (C) that was loitering in LEO performs a TLI burn to put it into a free return trajectory that will see it returning at the same time as Tanker A (I'm not sure the orbital mechanics will work for this, depends on the orbit used by the lunar Starship). Enroute back from the moon tanker C then provides tanker A with sufficient fuel for both of them to capture into earth orbit and perform EDL.
I am not even 100% sure you could do it with three - it might be necessary to have a fourth tanker in LEO waiting to replenish A and C when they have captured into orbit, since Starship needs a reasonable amount of fuel for EDL as I don't believe the TPS is sufficient for it to just mash straight into the Earth's atmosphere for either aerocapture or a straight re-entry?
Edited by Flooble on Tuesday 20th April 21:47
An orbital fuel depot is not a bad idea, because it could be kept topped up at a more leisurely and routine pace. It's not a new idea, but nothing like on the scale that would be required for Starship.
https://en.wikipedia.org/wiki/Propellant_depot
https://en.wikipedia.org/wiki/Propellant_depot
Meanwhile, Amazon plan to start launching their $10 Billion rival to Starlink - the snappily-titled Project Kuiper.
Since Jeff Bezos has no orbital rocket of his own yet, they've just bought nine Atlas V launches from ULA as a starter. They'll use other providers as and when they can.
They intend to have an initial constellation of 3,236 satellites, but their FCC licence is time limited, so they need to get going or they'll lose it. They have to put half the satellites in orbit by 2026 and the rest by 2029, so the clock is ticking.
Trouble is, they're about halfway through designing their satellites, let alone manufacturing them, so I expect these launches will begin next year at the earliest. They haven't said yet.
Since Jeff Bezos has no orbital rocket of his own yet, they've just bought nine Atlas V launches from ULA as a starter. They'll use other providers as and when they can.
They intend to have an initial constellation of 3,236 satellites, but their FCC licence is time limited, so they need to get going or they'll lose it. They have to put half the satellites in orbit by 2026 and the rest by 2029, so the clock is ticking.
Trouble is, they're about halfway through designing their satellites, let alone manufacturing them, so I expect these launches will begin next year at the earliest. They haven't said yet.
Beati Dogu said:
Meanwhile, Amazon plan to start launching their $10 Billion rival to Starlink - the snappily-titled Project Kuiper.
Gerald P Kuiper was a pioneer in planetary science. The old NASA flying infra-red telescope aircraft (a Lockheed C-141A Starlifter) was called the Gerald P Kuiper Laboratory in his memory.He is also the chap the Kuiper Belt is called after as he predicted its existence decades before the first Kuiper Belt Objects were detected.
A starship in LEO IS a fuel depot - 1200 tonnes is a lot of fuel. It has to be said, methane is looking to be an inspired choice for both Mars and the Moon. Having hydrogen liquified for any material duration is challenging, but you can have methane as a liquid at reasonable temperatures and pressures.
I suspect tanker efficiency will come down to how much weight they can strip out of a tanker Starship. But overall it points to the fact that manufacturing and fuel production needs to be done in Space - lugging everything from earth is just too hard.
I suspect tanker efficiency will come down to how much weight they can strip out of a tanker Starship. But overall it points to the fact that manufacturing and fuel production needs to be done in Space - lugging everything from earth is just too hard.
Beati Dogu said:
Meanwhile, Amazon plan to start launching their $10 Billion rival to Starlink - the snappily-titled Project Kuiper.
Since Jeff Bezos has no orbital rocket of his own yet, they've just bought nine Atlas V launches from ULA as a starter. They'll use other providers as and when they can.
They intend to have an initial constellation of 3,236 satellites, but their FCC licence is time limited, so they need to get going or they'll lose it. They have to put half the satellites in orbit by 2026 and the rest by 2029, so the clock is ticking.
Trouble is, they're about halfway through designing their satellites, let alone manufacturing them, so I expect these launches will begin next year at the earliest. They haven't said yet.
I noted that with some interest - what’s an Atlas V launch cost? How many satellites can it deploy in one go? What’s the launch cadence going to be? Since Jeff Bezos has no orbital rocket of his own yet, they've just bought nine Atlas V launches from ULA as a starter. They'll use other providers as and when they can.
They intend to have an initial constellation of 3,236 satellites, but their FCC licence is time limited, so they need to get going or they'll lose it. They have to put half the satellites in orbit by 2026 and the rest by 2029, so the clock is ticking.
Trouble is, they're about halfway through designing their satellites, let alone manufacturing them, so I expect these launches will begin next year at the earliest. They haven't said yet.
I suspect ether answer to all those questions is going to be a very bad one compared to the cost per satellite on a stack of Starlinks going up. I guess Amazon just need to get things moving, sod the cost.
Amazon didn't start Project Kuiper until 2019, so they're way behind Starlink and even OneWeb. They haven't even had any test satellites launched. They were supposed to have their FCC application in by 2016 like nine other companies did, but requested a special waver. Something the others are lobbying the FCC to deny. There's all sorts of legal & lobbying shenanigans going on between these guys to hamper each other's efforts.
Each Atlas V launch is likely to cost around $100 million each, even with a block discount. They can thank SpaceX that it's not more like $200 million, like it used to be. Nothing is known about the satellites yet, or how many they can fit on an Atlas V. Assume they'll just copy the Starlink model of a skinny, fold out design to fit as many in as they can - 50-60 maybe.
ULA aren't exactly used to a fast launch cadence and they'll have to fit these in between their usual defence / NASA work. They haven't launched one yet this year and they only did five Atlas V launches in the whole of last year. They've only got one launch pad for it in Florida, unlike SpaceX, and it will share duties with their new Vulcan rocket from later this year too. If they can launch one for Amazon every month I'd be surprised.
Each Atlas V launch is likely to cost around $100 million each, even with a block discount. They can thank SpaceX that it's not more like $200 million, like it used to be. Nothing is known about the satellites yet, or how many they can fit on an Atlas V. Assume they'll just copy the Starlink model of a skinny, fold out design to fit as many in as they can - 50-60 maybe.
ULA aren't exactly used to a fast launch cadence and they'll have to fit these in between their usual defence / NASA work. They haven't launched one yet this year and they only did five Atlas V launches in the whole of last year. They've only got one launch pad for it in Florida, unlike SpaceX, and it will share duties with their new Vulcan rocket from later this year too. If they can launch one for Amazon every month I'd be surprised.
Beati Dogu said:
ULA aren't exactly used to a fast launch cadence and they'll have to fit these in between their usual defence / NASA work. They haven't launched one yet this year and they only did five Atlas V launches in the whole of last year. They've only got one launch pad for it in Florida, unlike SpaceX, and it will share duties with their new Vulcan rocket from later this year too. If they can launch one for Amazon every month I'd be surprised.
Meanwhile, SpaceX have done, what, ten launches this year already?!"Bad weather offshore has forced SpaceX and NASA to delay tomorrow's planned launch of the Crew Dragon by a day. Better conditions are expected on Friday for a 05:49 am EDT (0949 GMT) liftoff from the Kennedy Space Center"
https://spaceflightnow.com/2021/04/15/falcon-9-cre...
https://spaceflightnow.com/2021/04/15/falcon-9-cre...
loudlashadjuster said:
Beati Dogu said:
ULA aren't exactly used to a fast launch cadence and they'll have to fit these in between their usual defence / NASA work. They haven't launched one yet this year and they only did five Atlas V launches in the whole of last year. They've only got one launch pad for it in Florida, unlike SpaceX, and it will share duties with their new Vulcan rocket from later this year too. If they can launch one for Amazon every month I'd be surprised.
Meanwhile, SpaceX have done, what, ten launches this year already?!ULA haven't actually launched a commercial satellite since December 2016 (EchoStar 19). Their next one is in the second half of next year.
MartG said:
"Bad weather offshore has forced SpaceX and NASA to delay tomorrow's planned launch of the Crew Dragon by a day. Better conditions are expected on Friday for a 05:49 am EDT (0949 GMT) liftoff from the Kennedy Space Center"
https://spaceflightnow.com/2021/04/15/falcon-9-cre...
Is this still planned for same time tomorrow morning?https://spaceflightnow.com/2021/04/15/falcon-9-cre...
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