Winston
Lorenzo von Matterhorn
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The right rocket for the moon and Mars
Apollo astronaut Jack Schmitt makes a detailed case for why NASA's Space Launch System beats the commercial alternatives.
06/15/2018
https://www.politico.com/story/2018/06/15/mars-moon-rocket-jack-schmitt-636632
Excerpt:
We need to launch a lot of infrastructure to deep space
There are two components to this requirement: Mass performance to deep space, and volume capability. The most recent comparison is that SLS Block 1 can launch ~95 mT while Falcon Heavy can launch ~64 mT to Low Earth Orbit. However, using LEO performance is not the correct measure for deep space mission requirements. However, using LEO performance is not the correct measure for deep space mission requirements. Some launch systems designs enable high performance to LEO, but are not efficient for missions beyond LEO. Also, SLS Block 1 is not the right vehicle to use in comparison, as it is a test vehicle. Future exploration mission launches will utilize the SLS Block 1B with the Exploration Upper Stage (EUS). As such, a more accurate performance comparison is that SLS Block 1B can launch ~40 mT to the Moon, with future additional growth potential that can include crewed landings. The Falcon Heavy can launch only ~20 mT to the Moon (assuming full performance without recovery of its first stage booster). As such, the true performance comparison is that it would take 2 Falcon Heavy launches to lift the same payload mass as an SLS Block 1B.
However, mass is just the beginning of the story. The SLS Block 1B fairing can accommodate 537m3, a little more than 3 times that the Falcon Heavy fairing can accommodate. Large volume is important because some systems arent well suited to being shipped in parts and assembled in space. It can be donemuch as a canoe can be cut up, packed inside an SUV, and driven to a lakebut there is added hardware needed to join the pieces and seal the joints. Greater complexity means added cost and risk of delay or mission failure, and extra hardware adds mass and takes up otherwise usable space. For deep space systems, these are serious constraints. SLS Block 1B can launch a fully outfitted ~40mT habitat with ~270 m3 usable volume to the Moon. To provide the same capability with the Falcon Heavy, therefore, would take 4-6 launches and re-assembly at the final location, once both mass and volume constraints are taken into account.
Cost comparison
Once one understands the key mission requirements, a price-per-pound comparison simply doesnt make sense; rather, a use-based cost comparison is clearly the better metric. Assuming a fully expendable Falcon Heavy launch costs $150-200M, the total comparative price of carrying infrastructure to deep space would be $600M to $1.2BM for 4-6 Falcon Heavy launches compared to $500-$1,000M for a SLS Block 1B launch. The SLS approach is similarly priced but less risky, as there is a significant increase in logistics and risk when a mission requires 100 percent success of 4-6 launches versus a single launch. There are also risks in operations with assembly of numerous components. Interfaces may not match up in zero g and different temperatures the way they did in Earth-based testing. This was a considerable risk for the International Space Station, adding significant cost and complexity to the program. In deep space, difficulties in integration become amplified due to the distances and risks involved in mitigation.
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First, for what lunar or Mars mission is the SLS designed for, one that will actually be funded?
Second, let's see, what kind of boosters did we launch the ISS into orbit with, successfully assembling the entire, huge facility (925,335 pounds (419,725 kilograms)) on orbit?
Third, on the SLS cost per flight, how many times do government or government contractor cost projections turn out to be accurate?
Fourth, putting biologically dirty human life on Mars before current or past indigenous life is detected there will forever present the problem of whether or not the life is native or a product of our contamination. Since the most profound discovery ever would be the determination of whether life is unique to the Earth or not, that wouldn't be wise. There's no hurry in the search for life and even less of a hurry to put humans on Mars.
Apollo astronaut Jack Schmitt makes a detailed case for why NASA's Space Launch System beats the commercial alternatives.
06/15/2018
https://www.politico.com/story/2018/06/15/mars-moon-rocket-jack-schmitt-636632
Excerpt:
We need to launch a lot of infrastructure to deep space
There are two components to this requirement: Mass performance to deep space, and volume capability. The most recent comparison is that SLS Block 1 can launch ~95 mT while Falcon Heavy can launch ~64 mT to Low Earth Orbit. However, using LEO performance is not the correct measure for deep space mission requirements. However, using LEO performance is not the correct measure for deep space mission requirements. Some launch systems designs enable high performance to LEO, but are not efficient for missions beyond LEO. Also, SLS Block 1 is not the right vehicle to use in comparison, as it is a test vehicle. Future exploration mission launches will utilize the SLS Block 1B with the Exploration Upper Stage (EUS). As such, a more accurate performance comparison is that SLS Block 1B can launch ~40 mT to the Moon, with future additional growth potential that can include crewed landings. The Falcon Heavy can launch only ~20 mT to the Moon (assuming full performance without recovery of its first stage booster). As such, the true performance comparison is that it would take 2 Falcon Heavy launches to lift the same payload mass as an SLS Block 1B.
However, mass is just the beginning of the story. The SLS Block 1B fairing can accommodate 537m3, a little more than 3 times that the Falcon Heavy fairing can accommodate. Large volume is important because some systems arent well suited to being shipped in parts and assembled in space. It can be donemuch as a canoe can be cut up, packed inside an SUV, and driven to a lakebut there is added hardware needed to join the pieces and seal the joints. Greater complexity means added cost and risk of delay or mission failure, and extra hardware adds mass and takes up otherwise usable space. For deep space systems, these are serious constraints. SLS Block 1B can launch a fully outfitted ~40mT habitat with ~270 m3 usable volume to the Moon. To provide the same capability with the Falcon Heavy, therefore, would take 4-6 launches and re-assembly at the final location, once both mass and volume constraints are taken into account.
Cost comparison
Once one understands the key mission requirements, a price-per-pound comparison simply doesnt make sense; rather, a use-based cost comparison is clearly the better metric. Assuming a fully expendable Falcon Heavy launch costs $150-200M, the total comparative price of carrying infrastructure to deep space would be $600M to $1.2BM for 4-6 Falcon Heavy launches compared to $500-$1,000M for a SLS Block 1B launch. The SLS approach is similarly priced but less risky, as there is a significant increase in logistics and risk when a mission requires 100 percent success of 4-6 launches versus a single launch. There are also risks in operations with assembly of numerous components. Interfaces may not match up in zero g and different temperatures the way they did in Earth-based testing. This was a considerable risk for the International Space Station, adding significant cost and complexity to the program. In deep space, difficulties in integration become amplified due to the distances and risks involved in mitigation.
------
First, for what lunar or Mars mission is the SLS designed for, one that will actually be funded?
Second, let's see, what kind of boosters did we launch the ISS into orbit with, successfully assembling the entire, huge facility (925,335 pounds (419,725 kilograms)) on orbit?
Third, on the SLS cost per flight, how many times do government or government contractor cost projections turn out to be accurate?
Fourth, putting biologically dirty human life on Mars before current or past indigenous life is detected there will forever present the problem of whether or not the life is native or a product of our contamination. Since the most profound discovery ever would be the determination of whether life is unique to the Earth or not, that wouldn't be wise. There's no hurry in the search for life and even less of a hurry to put humans on Mars.
