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Moonguy

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About Moonguy

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    Meson

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  • Favorite Area of Science
    Space Exploration
  1. Consider an unmanned lunar cargo lander that delivers 5,000 kg to the lunar surface. The delta-v for landing from a low lunar orbit is 2,100 m/sec. and the Moon's gravity is .16 Earth's. Now, consider that same lander used to land a payload on Mercury from a low Mercury orbit where the delta-v involved is 3,200 m/sec. Mercury's gravity is .38 Earth's. All of the physical characteristics of the lander must remain the same, only the payload mass can be altered. How much payload must be off-loaded to accomplish the landing? Thank you. . .
  2. The Shuttle experiment ended when the tether snapped. It was one of those embarrassing failures no one at NASA likes to remember.
  3. This is huge news, but I am curious why it was not posted under 'Medical Science'?
  4. Exactly how do we define a 'killer' asteroid? Asteroids currently zipping past Earth range around one to two kilometers in size. Is this large enough to prompt the mass extinction events that have occurred periodically? Or is a larger body required?
  5. Actually, this sounds like the '60's sci-fi movie 'Marooned'. Only it was the American (Apollo) that was stranded and a Russian spacecraft (Voskhod?) came up to rescue. A good yarn if patently unrealistic. . .
  6. Actually, they would need a pressure suit. You can deliver oxygen to the lungs at sufficient pressure without a suit. The problem is that, on Titan, the air pressure is 45% greater than at Earth's surface. Our skin surface, like everything else about us, evolved in Earth's atmospheric pressure and is suited to that. If you increase the pressure 45%, you would get gas diffusion effects into the subcutaneous tissues and eventually the blood stream. Not a good thing when cyanide is one of the chemicals in the 'air'. Other chemicals like ethane permeate into the tissue - in this case at high
  7. 1) The Tanker departs on a solar sail, so we only need the easiest departure point. Most cargo missions will depart from L3, but the Tanker takes on water from the Moon, so Tankers depart from orbits closer to the Moon but with easy departure velocities. That would be either L1 or L2. On reflection, L2 might actually be better as it does not interfere with operations (depots) in the L1 orbit. 2) The Tanker is an expendable unit. There is no need to worry about coordinating or synchronizing the Tanker's orbit for either picking up the crew (for the return to Earth) or for follow-on miss
  8. 1) All water/cryogens comes from the Moon. There is no Depot involved. All water/propellant transfers are direct to vehicle. 2) 'Departure Stage' is a misnomer. The stage carrying a solar sail only delivers a payload of 15 tons to the L1 point. The 15 ton payload includes propellant production equipment, a habitat module and the solar sail. At L1, the tanks of the delivery stage are filled with water, the solar sail deploys and the entire assembly departs into a heliocentric orbit with a one-year period. This orbit intersects the orbit of Mercury at one of the nodal crossings. 3) Th
  9. The 'Cycler' concept has dropped off the radar. For now, the idea is to focus on the first few ('Alpha') missions based on non-recovered systems. A departure stage is sent to L1. This unit carries a payload of 15 tons. This includes a solar sail (3880) kg, a self-deploying habitat (NOT a 'tin can'), and a docking module. The stage is equipped with water electrolysis units (as in the case of the Cycler), liquefaction and propellant transfer equipment. At L1, the propulsion stage's tanks are filled with up to 100 tons of water. The solar sail and habitat module are deployed and the clus
  10. Virtually everything you are saying is why I am confident about the 'transportation problem' (to Mercury) being solved. I particularly agree with you about the need for new ideas to 'percolate'. I grew up in a space advocacy that torpedoed itself with incessant arguing over 'where to go first' or who's idea for how to go was better. . . It made the entire movement a joke. Sadly, I have to admit I engaged in many of these arguments. I like to think I have evolved to where I see the value in 'synergy'. In the present case, this means using Mercury to boost astronomy and planetary explorat
  11. All of the life-support and agricultural technology issues are already being worked on in the interest of lunar and Mars exploration. The assumption here is that Mercury simply draws on technologies developed with experience from those two venues. The same goes for mining and mineral processing technologies. This is one of the reasons why the Mercury project is so cost effective. There is very little 'Mercury specific' technology needed, at least not in the early stages. Transportation is probably the biggest exception. Solar thermal is my choice for sending crews to Mercury, but has
  12. The entire purpose of the project is to establish a permanent base on Mercury to make Mercury useful. The economics strongly favor a base over a brief visit. So the first crew has the challenge of setting up a base that can house an engineering crew and a science/exploration crew. This includes a lab where hundreds of kilograms of rock samples can be examined instead of the minimal amount that could be sent back on a return flight. The construction work can be done at night under lights with the goal of having the base covered (as needed) as soon before sunrise as possible. As a though
  13. Radiation dangers are about how much exposure you allow the crew to have. The mass of the crew module for the inter-planet transfer phases is critical in this respect. Right now, the concept of choice is for a laminate radiation shield and use of both potable and waste water (in separate units!) to absorb radiation. It is easy to design shielding mass for any given material or even a series of layered material. The hard part is putting it all together in a mass that can be launched for well below the national debt in cost. The most dangerous exposure time is the period when the crew be
  14. Good clarifications, thanks! Regarding the reflector/concentrator, why are they made of anything rigid at all? Solar sail films already exist with 10 GRAM/m2 density. They ;also have 90% reflectivity. The materials available - at least the samples I have held in my hands - are strong enough to be integrated into an inflatable structure or even a mechanical arrangement like that in an umbrella. Adding scrim or other items to strengthen the reflector material is easily accommodated well with in the 1 kg/m2 mass limit. The system you describe has a lot of flexibility. I have to think a
  15. This occurred to me while I was reading the earlier posts: Would it not be possible to channel the concentrated light into the thrust chamber through fiber-optic cables? This would make the orientation of the reflectors independent of the thrust vector. The light from the fiber-optics concentrates inside the chamber as in other concepts, but does not require the chamber to be designed with exotic materials in order to allow light through. I have not had time to check it out, but it would seem this could scale sufficiently for use by a manned vehicle. . . especially one going to Mercury (o
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