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posted by janrinok on Friday April 20 2018, @06:12PM   Printer-friendly
from the refried-space-beans dept.

NASA is going back to the Moon, perhaps permanently, as seen in a new road map (image):

Four months after President Trump directed NASA to return to the Moon, the agency has presented a road map to meet the goals outlined in Space Policy Directive-1. The updated plan shifts focus from the previous "Journey to Mars" campaign back to the Moon, and—eventually—to the Red Planet.

"The Moon will play an important role in expanding human presence deeper into the solar system," said Bill Gerstenmaier, associate administrator of the Human Exploration and Operations Mission Directorate at NASA, in a release issued by the agency.

While the revamped plan may share the same destination as the Apollo program, NASA said it will approach the return in a more measured and sustainable manner. Unlike humanity's first trip to the Moon, the journey back will incorporate both commercial and international partners.

To achieve this, NASA has outlined four strategic goals:

  • Transition low-Earth orbit (LEO) human spaceflight activities to commercial operators.
  • Expand long-duration spaceflight activities to include lunar orbit.
  • Facilitate long-term robotic lunar exploration.
  • Use human exploration of the Moon as groundwork for eventual human missions to Mars and beyond.

This may be the best outcome for the space program. Let NASA focus on the Moon with an eye towards permanently stationing robots and humans there, and let SpaceX or someone else take the credit for a 2020s/early-2030s manned Mars landing. Then work on a permanent presence on Mars using cheaper rocket launches, faster propulsion technologies, better radiation shielding, hardier space potatoes, etc.

Previously: President Trump Signs Space Policy Directive 1

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  • (Score: 1) by khallow on Sunday April 22 2018, @10:08AM

    by khallow (3766) Subscriber Badge on Sunday April 22 2018, @10:08AM (#670296) Journal

    Various estimates I've seen put the cost of propellant for 1 BFR launch at below $1 million.

    Looks like I need to revisit the economics. I didn't realize both how cheap methane was and the mass fraction of the BFR (due to the higher ISP of the methane engine combined with some assumptions that they'll be able to keep the dry mass of the vehicle down) which is in itself revolutionary.

    That's a quite impressive mass fraction, if true - roughly 1400 mt vehicle fueled with 150 mt payload. The Falcon Heavy has the same launch mass (1420 mt [wikipedia.org], according to Wikipedia), but only puts about 40% as much into space (up to 64 mt in the non-reusable mode). The latter is typical of LOX/kerosene rocket vehicles.

    Anyway, my calculation yields a liquid methane price that is in itself somewhere around $1 per kg (maybe as much as $2 per kg - converting from normal natural gas which is under $1 per kg currently to pure liquid methane has some cost, but it can't be that much) and a liquid oxygen cost which is way under $1 per kg (I've seen old estimates of $0.16 per kg which are probably not that far off). For 1100 mt, that means a cost under $1 million, if they can maintain the mass fraction.

    This is more than just a big rocket, if they can manage to achieve the mass fraction above. I'm leaning towards betting against it. Methane is pretty fluffy and the ISP improvement is not that good. The Merlin 1D which uses kerosene/LOX has an ISP of 282 sec^-1 versus Raptor ISP of 330 sec^-1 - both at sea level - one atmosphere of external pressure. My math indicates that the Falcon Heavy has a dry mass (including payload, vehicle structure, rocket engines and propellant for returning the stages) of around 100 mt. Using the better ISP number only increases overall dry mass from 100 mt to 145 mt. I guess I'm missing something major.

    But my take is that a 1400 mt vehicle with Raptor engines of the advertised performance, doesn't have enough propellant mass to put 150 mt up. Using the same one third mass as the non-reusable Falcon Heavy (yielding an overall dry mass of 200 mt), would put the rocket's actual fueled mass around 2000 mt. Still pretty cheap propellant-wise, assuming that they can meet that.