SpaceX Tuesday...
Discussion
Clive Milk said:
Of course I went to bed and then fell asleep before missing this milestone.
Well done SpaceX. The new bits seem to be good, whenever testing new stuff it could go wrong but those pernickety Raptors may have been tamed for descent.
They are still never going to get to Mars but at least they are launching.
I see the poke at Jeff on Twitter by Elon on "getting it up" has finally got Blue Origin to do a manned sub orbital flight.
What makes you think they won’t make it to Mars? They’re not exactly a company with a track record of giving up on things and not achieving targets? Well done SpaceX. The new bits seem to be good, whenever testing new stuff it could go wrong but those pernickety Raptors may have been tamed for descent.
They are still never going to get to Mars but at least they are launching.
I see the poke at Jeff on Twitter by Elon on "getting it up" has finally got Blue Origin to do a manned sub orbital flight.
MiniMan64 said:
Clive Milk said:
Of course I went to bed and then fell asleep before missing this milestone.
Well done SpaceX. The new bits seem to be good, whenever testing new stuff it could go wrong but those pernickety Raptors may have been tamed for descent.
They are still never going to get to Mars but at least they are launching.
I see the poke at Jeff on Twitter by Elon on "getting it up" has finally got Blue Origin to do a manned sub orbital flight.
What makes you think they won’t make it to Mars? They’re not exactly a company with a track record of giving up on things and not achieving targets? Well done SpaceX. The new bits seem to be good, whenever testing new stuff it could go wrong but those pernickety Raptors may have been tamed for descent.
They are still never going to get to Mars but at least they are launching.
I see the poke at Jeff on Twitter by Elon on "getting it up" has finally got Blue Origin to do a manned sub orbital flight.
What's the roundtrip time to LEO?
What's the roundtrip time to the moon?
Now tell me what the round trip time is to Mars and whether an iterative test and fail approach is going to work for there.
Clive Milk said:
The last space X booster landing on the drone ship was inch perfect as well, amazing accuracy. We now almost take it for granted.
Yes, but the one previous wasn't - it wasn't far off, but certainly not central. I'd say we can't take it for granted just yet - and I'm a firm supporter of Space X and their progress (well, I like to watch their launches and landings etc).Clive Milk said:
What's the round trip time to 10km?
What's the roundtrip time to LEO?
What's the roundtrip time to the moon?
Now tell me what the round trip time is to Mars and whether an iterative test and fail approach is going to work for there.
I think that this has been explained before: 95% of the iteration will be done by the time they leave LEO. Once you leave LEO, you have proven:What's the roundtrip time to LEO?
What's the roundtrip time to the moon?
Now tell me what the round trip time is to Mars and whether an iterative test and fail approach is going to work for there.
- Orbital launch
- Re-entry
- Propulsive landing
- Orbital refuelling
With that under your belt, getting to Mars is simply a case of lighting up the engines to give you enough thrust to get there, then relighting them at the other end to put you in orbit. So they will definitely get to Mars.
Landing on Mars is hard. Less atmosphere = faster re-entry, but less gravity too. But these guys have computers and stuff to work it out - the physics of Mars is well known. I imagine they will test a lot of this with some really brutal re-entry profiles back to Earth.
Actually planting the ship on Mars - really hard, and I think that will be the remainder of the iteration. I have no idea how you’d land Starship on an unprepared surface. At a guess the first lander will have clown size feet.
Keeping humans alive for 6 months in space? We’ve done it on the ISS, so it is hard, but a solved problem. Keeping them alive for years on Mars? No idea. Making fuel on Mars - the chemistry makes sense, but setting up an industrial process will be stupidly difficult.
rxe said:
Clive Milk said:
What's the round trip time to 10km?
What's the roundtrip time to LEO?
What's the roundtrip time to the moon?
Now tell me what the round trip time is to Mars and whether an iterative test and fail approach is going to work for there.
I think that this has been explained before: 95% of the iteration will be done by the time they leave LEO. Once you leave LEO, you have proven:What's the roundtrip time to LEO?
What's the roundtrip time to the moon?
Now tell me what the round trip time is to Mars and whether an iterative test and fail approach is going to work for there.
- Orbital launch
- Re-entry
- Propulsive landing
- Orbital refuelling
With that under your belt, getting to Mars is simply a case of lighting up the engines to give you enough thrust to get there, then relighting them at the other end to put you in orbit. So they will definitely get to Mars.
Landing on Mars is hard. Less atmosphere = faster re-entry, but less gravity too. But these guys have computers and stuff to work it out - the physics of Mars is well known. I imagine they will test a lot of this with some really brutal re-entry profiles back to Earth.
Actually planting the ship on Mars - really hard, and I think that will be the remainder of the iteration. I have no idea how you’d land Starship on an unprepared surface. At a guess the first lander will have clown size feet.
Keeping humans alive for 6 months in space? We’ve done it on the ISS, so it is hard, but a solved problem. Keeping them alive for years on Mars? No idea. Making fuel on Mars - the chemistry makes sense, but setting up an industrial process will be stupidly difficult.
Simple question.
Even landing on Mars is hard as you say, forget taking off again. Just ask any space agency apart from NASA, who have a great track record NOT with a test and fail approach
You claim
"95% of the iteration will be done by the time they leave LEO"
Where did you get that stat from ?
So Mars landing and take off is only 5%?
Edited by Clive Milk on Thursday 6th May 21:02
Clive Milk said:
What's the round trip time to Mars ?
Simple question.
Even landing on Mars is hard as you say, forget taking off again. Just ask any space agency apart from NASA, who have a great track record NOT with a test and fail approach
Round trip time is not a fixed thing because it depends on where Mars and Earth are in relation to one another. The fastest route to Mars is about 3 months, given a big enough fuel load and no payload. The slowest (but sensible route with less fuel/more payload) is several months more: about 9. The transfer windows that are the best time to go are every few years.Simple question.
Even landing on Mars is hard as you say, forget taking off again. Just ask any space agency apart from NASA, who have a great track record NOT with a test and fail approach
With your comments about iteration -- has it occurred to you that the first few starships that go there won't have people on board, nor will they necessarily have to wait for the results of previous launches? You could literally fly a fleet of half a dozen over, multiple attempts at landing aren't problematic when the whole ethos of the project involves building a factory that can build rockets cheaply.
Round trip is only relevant if these vehicles are coming back. The first ones probably won't be coming back.
People on board is a long way down the line.
CraigyMc said:
Clive Milk said:
What's the round trip time to Mars ?
Simple question.
Even landing on Mars is hard as you say, forget taking off again. Just ask any space agency apart from NASA, who have a great track record NOT with a test and fail approach
Round trip time is not a fixed thing because it depends on where Mars and Earth are in relation to one another. The fastest route to Mars is about 3 months, given a big enough fuel load and no payload. The slowest is several months more. The transfer windows that are the best time to go are every few years.Simple question.
Even landing on Mars is hard as you say, forget taking off again. Just ask any space agency apart from NASA, who have a great track record NOT with a test and fail approach
With your comments about iteration -- has it occurred to you that the first few starships that go there won't have people on board, nor will they necessarily have to wait for the results of previous launches? You could literally fly a fleet of half a dozen over, multiple attempts at landing aren't problematic when the whole ethos of the project involves building a factory that can build rockets cheaply.
Round trip is only relevant if these vehicles are coming back. The first ones probably won't be coming back.
People on board is a long way down the line.
Yes, it has. The big question of course is whether you send out lots of ships to save time, or then lose time when the first has some inherent problem and all the rest fail the same way. Or do you send them slowly one after another?
This is the conundrum and hence why NASA does not do suck it and see. And they are the experts.
Elon is talking about manned missions though, so I use that as a yardstick to judge Space X by.
Clive Milk said:
So Mars landing and take off is only 5%?
The Martian gravity well is tiny compared to Earths (it's about 1/4 the depth) and aerodynamic drag is pretty small compared to Earth due to the thin atmosphere. As a consequence, from Mars, Starship alone is easily capable of single-stage to orbit, there's no need for the superheavy booster to get into space.Clive Milk said:
... The big question of course is whether you send out lots of ships to save time, or then lose time when the first has some inherent problem and all the rest fail the same way. Or do you send them slowly one after another?...
Obviously, he's building a factory to do the former. it's already there.CraigyMc said:
Clive Milk said:
So Mars landing and take off is only 5%?
The Martian gravity well is tiny compared to Earths (it's about 1/4 the depth) and aerodynamic drag is pretty small compared to Earth due to the thin atmosphere. As a consequence, from Mars, Starship alone is easily capable of single-stage to orbit, there's no need for the superheavy booster to get into space.CraigyMc said:
Clive Milk said:
... The big question of course is whether you send out lots of ships to save time, or then lose time when the first has some inherent problem and all the rest fail the same way. Or do you send them slowly one after another?...
Obviously, he's building a factory to do the former. it's already there.Clive Milk said:
CraigyMc said:
Clive Milk said:
So Mars landing and take off is only 5%?
The Martian gravity well is tiny compared to Earths (it's about 1/4 the depth) and aerodynamic drag is pretty small compared to Earth due to the thin atmosphere. As a consequence, from Mars, Starship alone is easily capable of single-stage to orbit, there's no need for the superheavy booster to get into space.A single starship's landing payload mass landed on Mars is well over 100,000kg (this is payload, it's somewhere in the region of 100-200t, in addition to the mass of the starship itself).
Clive Milk said:
CraigyMc said:
Clive Milk said:
... The big question of course is whether you send out lots of ships to save time, or then lose time when the first has some inherent problem and all the rest fail the same way. Or do you send them slowly one after another?...
Obviously, he's building a factory to do the former. it's already there.As you said, iterative testing!
CraigyMc said:
Clive Milk said:
CraigyMc said:
Clive Milk said:
So Mars landing and take off is only 5%?
The Martian gravity well is tiny compared to Earths (it's about 1/4 the depth) and aerodynamic drag is pretty small compared to Earth due to the thin atmosphere. As a consequence, from Mars, Starship alone is easily capable of single-stage to orbit, there's no need for the superheavy booster to get into space.A single starship's landing payload mass landed on Mars is well over 100,000kg (this is payload, it's somewhere in the region of 100-200t, in addition to the mass of the starship itself).
Go Elon.
Clive Milk said:
CraigyMc said:
Clive Milk said:
So Mars landing and take off is only 5%?
The Martian gravity well is tiny compared to Earths (it's about 1/4 the depth) and aerodynamic drag is pretty small compared to Earth due to the thin atmosphere. As a consequence, from Mars, Starship alone is easily capable of single-stage to orbit, there's no need for the superheavy booster to get into space.Clive Milk said:
CraigyMc said:
Clive Milk said:
So Mars landing and take off is only 5%?
The Martian gravity well is tiny compared to Earths (it's about 1/4 the depth) and aerodynamic drag is pretty small compared to Earth due to the thin atmosphere. As a consequence, from Mars, Starship alone is easily capable of single-stage to orbit, there's no need for the superheavy booster to get into space.Mars has 1/6th Earth gravity = lower orbital velocity
CraigyMc said:
Clive Milk said:
CraigyMc said:
Clive Milk said:
... The big question of course is whether you send out lots of ships to save time, or then lose time when the first has some inherent problem and all the rest fail the same way. Or do you send them slowly one after another?...
Obviously, he's building a factory to do the former. it's already there.As you said, iterative testing!
Clive Milk said:
CraigyMc said:
Clive Milk said:
CraigyMc said:
Clive Milk said:
... The big question of course is whether you send out lots of ships to save time, or then lose time when the first has some inherent problem and all the rest fail the same way. Or do you send them slowly one after another?...
Obviously, he's building a factory to do the former. it's already there.As you said, iterative testing!
I don’t think SpaceX will send multiple Starships to Mars at once. Elon will want to but I don’t think NASA will let him, as there’s a chance that if one Starship crashes then they all will, and that would cause a big debris field which NASA doesn’t want. And since NASA is the customer for SpaceX will do what they’re told to do.
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