A further factor is how much gravity difference can the human body take between the toes and the head?We were designed to operate under a nearly fixed amount of gravity with some intermittent turning torque.Human beings are about 2 metres high (6'6").
I agree that astronauts can probably adapt to ~5-10rpm, which should be good enough for Mars-level gravity in something like a Bigelow Sundancer module. Heck, you could just build it after you orbited the module, inside the module. You could have an artificial-gravity section of the module where sleeping, exercising, and perhaps other activities that could benefit from artificial gravity (like fixing or making something... most rapid manufacturing techniques rely on gravity). Also, if even idle activity in artificial gravity is found to be helpful, computers and desks could be placed in the artificial gravity section.The ring wouldn't need to be sealed at all (in fact, it would best not be sealed), and should be able to be spun-down at any time. Any structural considerations should be handled by the structure of the ring.Just an idea.EDIT: Part of the benefit of this idea is that the whole artficial gravity mechanical system would be inside a pressurized environment, and thus could be fixed mid-flight using conventional hand tools without a difficult and risky EVA.
On a long trip, there may well be a need for repairing or even manufacturing parts. Rapid-prototyping machines almost all require gravity to work, especially powder-based ones.
Quote from: Robotbeat on 09/23/2010 03:05 pmOn a long trip, there may well be a need for repairing or even manufacturing parts. Rapid-prototyping machines almost all require gravity to work, especially powder-based ones.For the foreseeable future this won't be an issue and certainly not with current rapid prototype materials. None of them have even a small fraction of the strength of standard aerospace materials so there are no parts that will be repaired by rapid prototypes using today's technologies. If we posit some magic that can rapid prototype out of flight-grade materials, then we may not have to worry about gravity. No sense even putting it on the radar as its a completely "magic" technology at this point Paul
I have been thinking for some time that a major impact event in Mars younger days may have been responsible for a lot of things. Imagine an asteroid striking the planet at what is now the Hellas Basin. This pushed the core of the planet so hard that it bulged out the other side creating Tharsis and the big volcanoes. Phobos and Diemos couold be ejecta fron this event. This could also account for Mars elongated orbit.Anyone Mick.
Quote from: MickQ on 09/22/2010 06:48 amI have been thinking for some time that a major impact event in Mars younger days may have been responsible for a lot of things. Imagine an asteroid striking the planet at what is now the Hellas Basin. This pushed the core of the planet so hard that it bulged out the other side creating Tharsis and the big volcanoes. Phobos and Diemos couold be ejecta fron this event. This could also account for Mars elongated orbit.Anyone Mick.Given the decay in their orbits, one would surmise that the impact was fairly recent (~100 million yrs?) and not early solar system. To create the Tharsis bulge would have been like making Earth's moon.If Phobos is from Mars, it may have less water and hydrocarbons. However, it could be a composite body - it really does a need a manned visit.
Is Phobos tidally locked with Mars, or does it spin?
Quote from: Lars_J on 09/28/2010 01:11 amIs Phobos tidally locked with Mars, or does it spin?It is tidally locked, though it is not in a synchronous orbit so Mars spins beneath it.
Quote from: orbitjunkie on 09/28/2010 02:17 amQuote from: Lars_J on 09/28/2010 01:11 amIs Phobos tidally locked with Mars, or does it spin?It is tidally locked, though it is not in a synchronous orbit so Mars spins beneath it.If I recall correctly, Phobos is above the Mars horizon for something like 4 hours at a time, twice a day, for any location on the surface in a broadly equatorial region. From a base on the Mars facing end of Phobos multiple surface units could be teleoperated in succession during each orbit for hours at a time.Mick
Relaying through a few low-orbit comsats, it could be close to 24x7. I think the rovers already use Mars Odyssey and MRO to relay to Earth and Phoenix used Mars Express. It might be harder to track a spacecraft at Phobos because it's moving faster than Earth (angular speed, not absolute velocity!), but it should be doable.
Recent observations as thermal infrared wavelengths using the Planetary Fourier Spectrometer (PFS) instrument on Mars Express show a poor match between the rocks on Phobos and any class of chondritic meteorite known from Earth.These would seem to support the "re-accretion" models for the formation of Phobos, in which rocks from the surface of the Red Planet are blasted into Martian orbit to later clump and form Phobos."We detected for the first time a type of mineral called phyllosilicates on the surface of Phobos, particularly in the areas northeast of Stickney, its largest impact crater," said co-author Dr Marco Giuranna, from the Italian National Institute for Astrophysics in Rome.These phyllosilicate rocks are thought to form in the presence of water, and have been found previously on Mars."This is very intriguing as it implies the interaction of silicate materials with liquid water on the parent body prior to incorporation into Phobos," said Dr Giuranna."Alternatively, phyllosilicates may have formed in situ, but this would mean that Phobos required sufficient internal heating to enable liquid water to remain stable."
Quote from: alexterrell on 09/27/2010 12:27 pmQuote from: MickQ on 09/22/2010 06:48 amI have been thinking for some time that a major impact event in Mars younger days may have been responsible for a lot of things. Imagine an asteroid striking the planet at what is now the Hellas Basin. This pushed the core of the planet so hard that it bulged out the other side creating Tharsis and the big volcanoes. Phobos and Diemos couold be ejecta fron this event. This could also account for Mars elongated orbit.Anyone Mick.Given the decay in their orbits, one would surmise that the impact was fairly recent (~100 million yrs?) and not early solar system. To create the Tharsis bulge would have been like making Earth's moon.If Phobos is from Mars, it may have less water and hydrocarbons. However, it could be a composite body - it really does a need a manned visit.Alex. I agree. Phobos should be a priority target. I think it was Kkattula who recently posted that it is essentially a NEO with a great view. A perfect place for an outpost to conduct teleoperated research of Mars as well.Mick.