Quote from: Dalhousie on 01/24/2017 07:18 amIn 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.
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.
Could SLS work for a Mars Direct architecture?
Quote from: Oli on 01/25/2017 01:09 pmQuote from: Dalhousie on 01/24/2017 07:18 amIn 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.QuoteCould SLS work for a Mars Direct architecture?As a matter of fact, whatever the advantages or disadvantes of HLV, SLS seems to be unstoppable as far as Congress goes, despite the fact that so far it has exactly two missions on its flight manifest - EM-1 and EM-2. ....And it aparently lost Europa Clipper, so no science payloads to boost that anemic flight manifest.
That the National Aeronautics and7 Space Administration shall use the Space Launch System8 as the launch vehicles for the Jupiter Europa mission,9 plan for an orbiter launch no later than 2022 and a lander10 launch no later than 2024, and include in the fiscal year11 2020 budget the 5-year funding profile necessary to12 achieve these goals.
So, unless we already have crowned king Trump or NASA has completely gone off the rails, 2 Europa missions are on the manifest and as far as I can tell are 100% funded. Which means Falcon Heavy has 4 launches on the manifest and SLS has 4.
