Regarding 'what is and is not necessary' for the complete MCT spacecraft: I've been hearing figures for VASMIR-powered flight to Mars of around 5 or 6 weeks one-way. With this sort of flight duration, is any kind of gravity simulation of the spacecraft strictly necessary, especially assuming that, in between transfer orbits, the crew would be spending most or all of their time on Mars's surface?
FWIW, I'm still thinking of two distinct crewed flight modes: Its primary propulsion system would be eight Merlin-M in four dual clusters at the four corners.
What kind of specs are you thinking for this, Ben? I'm assuming the "M" stands for "Methane" here.
Yeah, basically a Merlin-VAC but using LCH4 as its propellent. The objective specifications of Merlin-M would be about the same thrust with about 360s-380s vacuum impulse. It's possible that eight engines for landing and early ascent is excessive but, if so, it at least provides a degree of redundancy.Raptor is probably going to be a very big engine at least in terms of volume and it might not be practical to fit it to MCT itself. If that is the case, then Merlin-M steps in as a 'baby Raptor'.
Look at pictures of the hypothetical 'Falcon-XX' and add Falcon-style landing legs and you've got a good idea of what BFR looks like. What MCT will look like is anyone's guess. It could be quite an elaborate design, straight out of Space: 1999 if it launches in a PLF.
@philw1776,Maybe this is me but I see the BFR (the Raptor-powered launch vehicle) and the MCT as two distinct projects and two distinct vehicles. The BFR (which I think of as 'Condor') is basically just a 120-ish t IMLEO launcher. MCT is the payload.Look at pictures of the hypothetical 'Falcon-XX' and add Falcon-style landing legs and you've got a good idea of what BFR looks like. What MCT will look like is anyone's guess. It could be quite an elaborate design, straight out of Space: 1999 if it launches in a PLF.
Question:Mars. Could you please clarify what the Mars Colonial Transporter actually is? Is it a crew module like Dragon, a launch vehicle like Falcon, or a mix of both? Does it have inflatable components? Is MCT just a codename? Elon's Answer: The Mars transport system will be a completely new architecture. Am hoping to present that towards the end of this year. Good thing we didn't do it sooner, as we have learned a huge amount from Falcon and Dragon.
In every case, he seems to be saying nuclear is not a particularly amazing option and generally solar is better (safer) or less heavy.I agree with him (although I don't think nuclear is quite as dangerous as he's implying), for the record. But especially in space, solar is much, much better.Nowhere does he give a hint that it's a likely fit for MCT, certainly not nuclear-thermal.
Quote from: Ben the Space Brit on 04/15/2015 10:52 am@philw1776,Maybe this is me but I see the BFR (the Raptor-powered launch vehicle) and the MCT as two distinct projects and two distinct vehicles. The BFR (which I think of as 'Condor') is basically just a 120-ish t IMLEO launcher. MCT is the payload.Look at pictures of the hypothetical 'Falcon-XX' and add Falcon-style landing legs and you've got a good idea of what BFR looks like. What MCT will look like is anyone's guess. It could be quite an elaborate design, straight out of Space: 1999 if it launches in a PLF.As I've posted over on the Raptor thread, I think you are on the right track for it's overall size. http://forum.nasaspaceflight.com/index.php?topic=34197.msg1357465#msg1357465120mt-ish, Saturn V-class. But I disagree that BFR and MCT will be two different things. I think they'll be an integrated system, not unlike STS. STS wasn't an LV and a spacecraft, it was a whole system that flew together. That's why we've never heard any seperate name for the booster. It's always just been referred to as by SpaceX and Elon as "MCT". And in fact, in Elon's Reddit interview, he basically said that here:
Quote from: spacenut on 04/04/2015 03:34 pmDoes anyone know how long it takes to liquefy a certain volume of oxygen and methane with existing equipment? The natural gas company I worked for liquefied gas during the summer when gas was abundant and cheap, but took 3-4 months to liquefy enough for 2 months winter use. These tanks were very large, around 50-75 meters in diameter, two walls, 3' between the walls where a vacuum was pulled, like a giant thermos bottle. I wasn't with that group, so I know very little about how much volume they could liquefy in a given time.Large volume of LNGSee the LNG tankers.The Grand Aniva carries 36,671 tons of LNG.Gotta luv a ton of gas.
Does anyone know how long it takes to liquefy a certain volume of oxygen and methane with existing equipment? The natural gas company I worked for liquefied gas during the summer when gas was abundant and cheap, but took 3-4 months to liquefy enough for 2 months winter use. These tanks were very large, around 50-75 meters in diameter, two walls, 3' between the walls where a vacuum was pulled, like a giant thermos bottle. I wasn't with that group, so I know very little about how much volume they could liquefy in a given time.
But you do need those big tanks on the MCT for the fuel for the Mars to Earth trip. Not so different from the second stage functionality.
But you do need those big tanks on the MCT for the fuel for the Mars to Earth trip. Not so different from the second stage functionality.Also most likely it will be refuelled on it's way to mars anyway, so not THAT big tanks.