NASA SLS/Orion/Payloads

[sevenperforce]

1 hour ago, tater said:

^^^Move that to the other thread.

On topic, anyone know the wet mass of the LockMart MADV upon Martian landing?

Well, the whitepaper doesn't list a dry mass, but it has the thing powered by six restartable RL-10 engines, so if you want an ascent TWR of 2:1 on Mars then you'd expect a takeoff mass of around 88.9 tonnes. They budget 780 m/s for EDL, so you'd expect a fully-loaded mass of 106 tonnes.

13 minutes ago, tater said:

Looks like their MADV is about 105 tons, wet, and Mars EDL is wet. Crew BFS is supposed to be ~85 tons dry, cargo on top. So at least twice as massive as the LM design at the upper limit. For a similar type of mission architecture (small crew, brief stay), BFS doesn't actually mass much more, though it might be stuck on the surface . Dunno what the min prop load is to make LMO, maybe it could carry extra props instead of cargo and be able to land, then make orbit (seems like it would be possible with the same number of launches as Mars Base Camp (6 SLS, 6 heavy commercial launches) to send a few BFR in a sort of MBC mission using alternate vessels.

You could put a BFS tanker into LMO pretty easily. Get two fully-loaded BFSs into LEO, have them both burn in parallel toward Mars until the apoapse is at the edge of the Earth's SOI, then have them dock, transfer propellant from one to the other, and then have one complete the TMI while the other returns to Earth. The one that heads to Mars can aerocapture and circularize with little expenditure of propellant.

[tater]

Yeah, so with the same small crew and supplies (since that the crew compartment is perhaps smaller, or mostly empty), the LM design is not terribly different from the SpaceX design (it looks to be almost 8 meters across, after all).

[DDE]

4 hours ago, sevenperforce said:

with 0-0 L/L abort and lifeboat capability

We have the huge problem of the BFR not having a stated fixed passenger capacity. It's easier to give it the ability to blast off from the booster.

[DAL59]

10 minutes ago, DDE said:

We have the huge problem of the BFR not having a stated fixed passenger capacity.

40 cabins.  You could cram 4 people in each for a short hopper flight, so 160 people.  

[sevenperforce]

3 hours ago, tater said:

Yeah, so with the same small crew and supplies (since that the crew compartment is perhaps smaller, or mostly empty), the LM design is not terribly different from the SpaceX design (it looks to be almost 8 meters across, after all).

Same size, not too dissimilar dV, either (LM has more energetic propellant but less of it, because hydrogen is denser fluffier than methane). One goes from Martian orbit to the surface of Mars and back; the other goes from Earth orbit to the surface of Mars or from the surface of Mars to the surface of Earth.

1 hour ago, DAL59 said:

1 hour ago, DDE said:

We have the huge problem of the BFR not having a stated fixed passenger capacity. It's easier to give it the ability to blast off from the booster.

40 cabins.  You could cram 4 people in each for a short hopper flight, so 160 people.  

For interplanetary missions, yes. But god help us if we are planning on sending 160 people from Earth to LEO in one flight.

Edited February 24, 2018 by sevenperforce

[sh1pman]

29 minutes ago, sevenperforce said:

hydrogen is denser than methane

You sure it’s not the other way round?

[PB666]

8 hours ago, Jaff said:

What exactly is so complicated about the rs25 in comparison to any other engine? 

Also LOL at an rs25 engine test being a milestone for SLS yet SX almost saving fairings when launching a satellite is just something we’ve been doing since the 60’s - cracking logic 

It has something like 4 turbo pumps, part of the fuel is ignited in one to run the pumps.

[sevenperforce]

39 minutes ago, sh1pman said:

You sure it’s not the other way round?

Dammit!

[PB666]

1 hour ago, sevenperforce said:

Same size, not too dissimilar dV, either (LM has more energetic propellant but less of it, because hydrogen is denser fluffier than methane). One goes from Martian orbit to the surface of Mars and back; the other goes from Earth orbit to the surface of Mars or from the surface of Mars to the surface of Earth.

For interplanetary missions, yes. But god help us if we are planning on sending 160 people from Earth to LEO in one flight.

help us? help them. The LEO part is nothing compared to the Mars entry and landing.

 

[sevenperforce]

17 minutes ago, PB666 said:

help us? help them. The LEO part is nothing compared to the Mars entry and landing.

 

Mars EDL is a one-time affair, for the most part, and you cannot very well abort in that event. BFR/BFS is supposed to be used many, many times in LEO, and if you have the capacity to include abort and don't use it, you're running an entirely unacceptable risk of LOC.

[tater]

For LEO, a dedicated crew version with a LES would make more sense to ferry people to a "real" spacecraft.

[sevenperforce]

5 minutes ago, tater said:

For LEO, a dedicated crew version with a LES would make more sense to ferry people to a "real" spacecraft.

Exactly. The Enterprise doesn't take off and land from Earth every time it comes by, after all.

[PakledHostage]

1 hour ago, sevenperforce said:

Exactly. The Enterprise doesn't take off and land from Earth every time it comes by, after all.

Exactly. Transporters. We need transporters.

[tater]

Once there is truly heavy lift for a reasonable cost, maybe NASA can start making spacecraft.

[T-10a]

Maybe we can finally see something akin to Nautilus-X zipping around with NG, Falcon Heavy and Vulcan doing grunt work. (maybe Roscosmos can come too if they get their stuff together)

Edited February 24, 2018 by T-10a

[DDE]

3 hours ago, T-10a said:

maybe Roscosmos can come too if they get their stuff together

On the one hand, I really doubt that would be politically acceptable.

On the other hand, Roscosmos is up for the DSG. Which at this point feels like not interrupting the enemy when they're making a mistake.

But hey, it's relevant to this thread because it would be an SLS payload.

[sh1pman]

58 minutes ago, DDE said:

Which at this point feels like not interrupting the enemy when they're making a mistake.

And here I thought Cold War was over. 

[DDE]

3 hours ago, sh1pman said:

And here I thought Cold War was over. 

It restarted circa 1998 and has continued on an on-and-off basis ever since.

[Canopus]

http://spacenews.com/nasa-foresees-human-lunar-landings-by-the-late-2020s/ 

i‘m hopeful but i‘m sure it will take a little bit longer.

[sevenperforce]

1 hour ago, Canopus said:

http://spacenews.com/nasa-foresees-human-lunar-landings-by-the-late-2020s/ 

i‘m hopeful but i‘m sure it will take a little bit longer.

We need higher-energy storables with orbital propellant transfer.

Or something like that.

Otherwise, sending a new multistage lander for every single mission is going to get really pricey, really fast, no matter how cheap our launches are.

[kerbiloid]

4 minutes ago, sevenperforce said:

We need higher-energy storables with orbital propellant transfer.

Or something like that.

Otherwise, sending a new multistage lander for every single mission is going to get really pricey, really fast, no matter how cheap our launches are.

Lunar rotovator.

Also it's a nice site about all this stuff.

[Canopus]

9 minutes ago, sevenperforce said:

We need higher-energy storables with orbital propellant transfer.

Or something like that.

Otherwise, sending a new multistage lander for every single mission is going to get really pricey, really fast, no matter how cheap our launches are.

Look into ACES and XEUS. I‘m sure they could be ready by the end of the 20‘s.

[Bill Phil]

16 minutes ago, sevenperforce said:

We need higher-energy storables with orbital propellant transfer.

Or something like that.

Otherwise, sending a new multistage lander for every single mission is going to get really pricey, really fast, no matter how cheap our launches are.

It only takes about 2.5 km/s of dv to land on the Moon from LLO. That's less than hydrolox's exhaust velocity, but hydrolox is difficult to store. It's also less than kerolox, methalox, and a few hypergolic propellant combinations. If we can get a moonbase going and harvest oxygen from lunar regolith and bring some hydrogen with us, we could refill the LOX tanks on the Moon. Some margin would be good to have, of course. Maybe a multi-stage system could work, but make them reusable, like a sort of mini BFR system optimized for lower dv to orbit?

[DDE]

23 minutes ago, sevenperforce said:

We need higher-energy storables

You don't say...

Is it ClF5 time? Is it time for hydrazine, pentaborane or beryllium? Is peroxide back in play?

1 minute ago, Bill Phil said:

It only takes about 2.5 km/s of dv to land on the Moon from LLO. That's less than hydrolox's exhaust velocity, but hydrolox is difficult to store. It's also less than kerolox, methalox, and a few hypergolic propellant combinations. If we can get a moonbase going and harvest oxygen from lunar regolith and bring some hydrogen with us, we could refill the LOX tanks on the Moon. Some margin would be good to have, of course. Maybe a multi-stage system could work, but make them reusable, like a sort of mini BFR system optimized for lower dv to orbit?

You might not want a SST-LLO lunar lander. I think we're going to see aluminum-oxygen before we'll see lunar hydrolox.

[sevenperforce]

1 hour ago, DDE said:

You don't say...

Is it ClF5 time? Is it time for hydrazine, pentaborane or beryllium? Is peroxide back in play?

I said higher-energy storables, not higher-energy hypergolics. Peroxide isn't exactly storable.

I suppose the other solution is storable cryogens.

Is Blue Moon supposed to be based on BE-3?