Could SLS work for a Mars Direct architecture?

[Robotbeat]

Yeah, because if you work at ULA and publish such a study, you'll get a firm talking-to by your boss since ULA is part owned by Boeing. This is a real constraint. And at NASA, you HAVE to include SLS in your architecture or you won't get past internal peer review. There are major political constraints on anyone planning a smaller chunk architecture.

[Dalhousie]

Yeah, because if you work at ULA and publish such a study, you'll get a firm talking-to by your boss since ULA is part owned by Boeing. This is a real constraint. And at NASA, you HAVE to include SLS in your architecture or you won't get past internal peer review. There are major political constraints on anyone planning a smaller chunk architecture.

Nothing to stop independent people and groups doping these studies. There are quite a few such Mars mission studies out there.  How many advocate doing things Lego style?

[Robotbeat]

So it went from "I haven't seen any" to me giving you 3 such examples to now you wanting an industry lit review to see how many there are... I hope you have a grant to fund my research on this topic!

...remember, even the Augustine thing suggested 40 tons was fine.

[Robotbeat]

Also, "Lego style" is outdated. No assembly required. Just refueling and perhaps docking a few elements.

[Oli]

In your opinion.  Oddly enough, I don't know of any study that supports this.  Do you know of a Mars mission study in the past 50 years that has used launchers with low Earth payloads of less than 50 tonnes and shown that this is superior to using larger boosters I would be most interested in seeing it.

The disadvantages of heavy lift I see:
- Very high development cost historically.
- Potentially low flight rate leading to high per launch cost.
- Doesn't share fixed cost with existing smaller launch vehicles.

The advantages:
- Bigger rockets are more efficient.
- Unique capability of launching large and heavy payloads.

If you look at past Mars architectures from NASA (the DRMs), the Mars landers have always been very big. Around 100t. The advantage is you only need 2 of them. If you go with smaller but more landers, as the more recent EMC does, you don't need a 100t+ to LEO vehicle. Still, existing launch vehicles aren't enough. With HIAD landers something around 40t-50t and a ~8m diameter fairing is probably the minimum. With mid L/D landers 60t-70t.

[robert_d]

If you look at past Mars architectures from NASA (the DRMs), the Mars landers have always been very big. Around 100t. The advantage is you only need 2 of them. If you go with smaller but more landers, as the more recent EMC does, you don't need a 100t+ to LEO vehicle. Still, existing launch vehicles aren't enough. With HIAD landers something around 40t-50t and a ~8m fairing is probably the minimum. With mid L/D landers 60t-70t.

I would be interested what could be done with a Falcon "4 core". It could support a fairing of 8 x 5.5 meters. If Falcon Heavy works and SLS were cancelled, it might be the only option. If assembled in the VAB there might be an opportunity to launch 2 in a Martian window from 39b and along with 1 Falcon Heavy from 39A and one from Boca Chica, you could get a substantial payload ready for TLI. The 4 core could support a full sized Raptor metholox second stage.

[Jim]

I would be interested what could be done with a Falcon "4 core".

No, that is unworkable. Just easier to build a larger diameter core.

[Jim]

It's much more efficient to minimise the number of launches.  Multiplying them increases the likelihood of delays. IMHO of course!

Not true.  It is more efficient to use cheaper and multiple types of vehicles and launch more often. 

[Robotbeat]

In your opinion.  Oddly enough, I don't know of any study that supports this.  Do you know of a Mars mission study in the past 50 years that has used launchers with low Earth payloads of less than 50 tonnes and shown that this is superior to using larger boosters I would be most interested in seeing it.

The disadvantages of heavy lift I see:
- Very high development cost historically.
- Potentially low flight rate leading to high per launch cost.
- Doesn't share fixed cost with existing smaller launch vehicles.

The advantages:
- Bigger rockets are more efficient.
- Unique capability of launching large and heavy payloads.

If you look at past Mars architectures from NASA (the DRMs), the Mars landers have always been very big. Around 100t. The advantage is you only need 2 of them. If you go with smaller but more landers, as the more recent EMC does, you don't need a 100t+ to LEO vehicle. Still, existing launch vehicles aren't enough. With HIAD landers something around 40t-50t and a ~8m fairing is probably the minimum. With mid L/D landers 60t-70t.

A large fairing doesn't require a large launch vehicle. For instance, Atlas V (which is fairly skinny) has the option of a 7.1m diameter fairing in its payload guide. An upgraded Delta IV Heavy or a Vulcan Heavy should be capable of 8m if anyone ordered such a fairing.

So the questions of fairing size and payload mass can be considered separately.

[robert_d]

Not true.  It is more efficient to use cheaper and multiple types of vehicles and launch more often.

Especially if one of the vehicles has two side boosters already in production that can do a RTLS and be re-used.

[robert_d]

Anyone know what thrust an "optimized" metholox 2nd stage to SLS would have if it was able to be refueled in orbit? Would a full sized raptor be anywhere in that neighborhood.?

[redliox]

Try not to veer too far off topic guys; Von Braun wasn't part of either STS or SLS, and this thread is meant to see how well the SLS could be utilized for Mars Direct.  For example, assume the current administration curtails extensive SLS development and we're stuck with the SLS 1B with no immediate relief from SpaceX's ITS.  In such a situation there'd still be a 105mt HLV and several smaller vehicles (SpaceX, Launch Alliance, ect) available, each with the potential to put a combination of large and small payloads directly on Mars which was the main point of Mars Direct: to bypass orbital assembly and focus on arriving at the red planet.

[Robotbeat]

Then yeah, of course. Docking (like Apollo) and refueling are not traditionally considered orbital assembly, and you can do a Mars mission just with those two and EELV class vehicles. If you want to add SLS 1B, then yeah, of course you can still do it.

[redliox]

Looking over the time frame of the immediate future, there would be 5 chief launch vehicles worthy of consideration for a Martian mission:

Falcon Heavy - due 2017
SLS - due 2018 (~2023 for Block 1B)
Vulcan - due 2019
New Glen - due 2020
ITS - due 2024

While Vulcan is on the light side of usefulness for a crewed Martian mission, I thought it fair to include since it will be ULA's upcoming crew launcher - and if it's man-rated that means it could be adapted for launching applicable payloads or a crew shuttle to LEO if nothing else.

I listed each rocket with their tentative first launch (per Wikipedia).  As the SLS and it's issues between EM-1 and EM-2 reveal, the first launch and the first useful payload of a LV may be 2 different things.  There could be development issues furthermore.  All the same, it does present a timetable to refer back to and debate on.

In the world of 2025 we'll definitely have the first 3 rockets available.  My guess will be that ITS and New Glen/New Armstrong will see some delays, since both their respective companies are honestly new at giant rockets, but could be on track for Mars operations between 2027-2030.  Considering how quiet Blue Origins keeps, New Glen may have a 50/50 chance of being operational before ITS but I believe it will be the crew vehicles that dictate their schedules in the end.  Even without the much-anticipated-secret-(moreso for Blue Origins)-weapons of Space X and BO, this could be enough to seed the first surface mission.

Under the assumption we don't want to wait on commercial-HLV, if I could design the mission setup, I'd requisition 4 SLS rockets and 4 FHs.  I only favor FH because SpaceX will have a head start on Red Dragon landers before Boeing/ULA could replicate the effort.  As per Mars Semi-Direct, there'd be 3 classes of crew vehicle: Hab, Mars Ascent Vehicle, and Earth Return Vehicle.  To play it safe, a Hab plus 4 Red Dragons would arrive at Mars before even the MAV and ERV.  A second Hab would either launch with crew directly or have the crew transfer via commercial taxi (Starliner or Dragon) in LEO.

[envy887]

Looking over the time frame of the immediate future, there would be 5 chief launch vehicles worthy of consideration for a Martian mission:

Falcon Heavy - due 2017
SLS - due 2018 (~2023 for Block 1B)
Vulcan - due 2019
New Glen - due 2020
ITS - due 2024
...
I listed each rocket with their tentative first launch (per Wikipedia). 
...

First launch of ITS is NET 2020. First crewed launch NET 2022. First interplanetary crewed launch NET 2024.

If you want to compare vehicle availability, I would advise using the same date reference for each. FH won't be ready to carry crew in 2017, nor SLS ready to carry crew in 2018.

[redliox]

If you want to compare vehicle availability, I would advise using the same date reference for each. FH won't be ready to carry crew in 2017, nor SLS ready to carry crew in 2018.

Actually it's the availability of the LV I was intentionally referring to, not whether it was capable of safely flying humans.  As an example: suppose NASA decides to go full commercial for crew vehicles but, prior to ITS or New Glen/New Armstrong, they wish to send out the base modules and cargo.  A flight tested, but only cargo ready LV, could be utilized while the final kinks of the commercial landers are worked out.  Further assuming NASA is jittery with payloads (as well as politics), that favors FH, SLS, and Vulcan for HSF hardware but no crews.

A key factor with Mars Direct was to establish a safety net for crew ahead of their mission.  Any rocket that can send better than a few tonnes to Mars is an asset.  Even if the SLS isn't matured to Block 2 before ITS arrives (in a figurative sense) 105 mt, with as much as 30 mt available for Mars, should remain a card on the table.

[Robotbeat]

Vulcan Heavy is about 40-50 tons IMLEO. And with "distributed launch" and an 8m fairing (which it could indeed utilize) it could launch anything to the Moon that SLS can.

[TrevorMonty]

Vulcan Heavy is about 40-50 tons IMLEO. And with "distributed launch" and an 8m fairing (which it could indeed utilize) it could launch anything to the Moon that SLS can.

Single stick Vulcan is <40t. Currently there is no plans to build a 3 core heavy version, but G Sower did say it is an option.

[Robotbeat]

Vulcan Heavy is about 40-50 tons IMLEO. And with "distributed launch" and an 8m fairing (which it could indeed utilize) it could launch anything to the Moon that SLS can.

Single stick Vulcan is <40t. Currently there is no plans to build a 3 core heavy version, but G Sower did say it is an option.

Tory Bruno tweeted this out. It's clearly an option, if anyone wants it.

https://mobile.twitter.com/torybruno/status/595628488410963970

[redliox]

Vulcan Heavy is about 40-50 tons IMLEO. And with "distributed launch" and an 8m fairing (which it could indeed utilize) it could launch anything to the Moon that SLS can.

Single stick Vulcan is <40t. Currently there is no plans to build a 3 core heavy version, but G Sower did say it is an option.

Tory Bruno tweeted this out. It's clearly an option, if anyone wants it.

It would be on par with FH alright.  I'm glad ULA is working to impress customers.