Nibb31

Dragon 2 always has been pretty much a dead end after the ISS contracts, which only represent a dozen flights. It's supposed to be reusable and so is F9, so the only production line they need is for the 2nd stage. If they divert production resources from Merlin to MVac and from lower stages to upper stages, they can build a decent stockpile of expendable upper stages to last a couple of years. FH has proven to be harder than they thought. Even Musk doesn't seem very confident that it will work.

Yes, that's how he intends to fund the thing: by shifting all resources towards BFR. I suspect they will stockpile Merlin engines and second stages and reuse all 1st stages. Don't expect F9 launches to become any cheaper. Any savings through reusability are going into BFR development. It's a huge gamble IMO. He is literally betting the entire company on reusability and BFR. Probably both. He sort of admitted that FH was a dead end. He said that he hoped to recover F9 fairings, but didn't mention recovering the second stage any more. There was also no mention of the constellation. I suspect he doesn't want to scare his customer base here.

Regardless of fuel cost, noise killed Concorde. A suborbital hypersonic projectile heading towards a major city center is not going to be very popular. The flight time might be under an hour, but you've got to take into account the total transit time, including transport to and from the launch/landing barge (by boat?), TSA checks, customs, boarding, etc... A P2P vehicle would probably be very different anyway. You wouldn't need those Vacuum Raptors, nor would it need header tanks. So it would probably be a completely different design.

The design seems to have matured a bit since last year, especially regarding the windows (I still suspect that it will lose even more as the design matures) and the stubby fins, which now seem to have been replaced by much more sensible winglets. I do like the refueling mode with ullage thrusters, although I can see it consuming a lot thruster fuel. I'm still not buying the solar arrays or the ground clearance. I don't believe in the viability of P2P suborbital flights either, nor do I think it will ever get certified to visit the ISS before the ISS is decommissioned. And there are still no plans as to how to fund the actual Mars infrastructure. What impressed me the most is shutting down F9 and FH production lines to fund this thing. F9 is their cash cow, so that is a huge risk. If F9 reusability turns out to be less efficient than expected, or if some fundamental design flaw delays ITS, then the whole company is toast.

We are lacking detail on the mission profile, but I suspect it goes something like: HAB launches on SLS+EUS Orion+ACES on SLS+EUS Orion+ACES docks with HAB EUS sends Orion+ACES+Hab to Mars Stack docks with other HAB and stuff in Mars orbit A lot of stuff doesn't add up, like can SLS+EUS launch Orion with an ACES ? Can ACES stages keep their cryo for a multi-year mission?

I don't think we will ever get to a point where people have individual spacecraft. The amount of energy required to accelerate a couple of tons to orbital speeds is just huge. Even if you find a way to contain that energy in a compact and safe enough package, that sort of energy would be way too destructive to have people keep in their garage or fly around risking collisions or putting it into malevolent hands.

Sure, but I have no idea how you get it to Mars with a full tank. Using cryos around Mars is going to be hard unless mission profile relies on ISRU from Phobos or something.

Welcome to the real world of spaceflight.

Actually, it looks exactly like ITS. The ITS videos of last year didn't really show the reentry or the flip manoeuver, but they are pretty much inevitable with that configuration.

Were you living under a rock for the last year ? BFR/BFS is ITS.

What's the point of increasing human population if it means that the we have to live miserably or emigrate to an even more hostile environment? Wouldn't it be smarter to gradually reduce human population through birth control so that a higher proportion can live more comfortably with less resources?

Call me a pessimist. I'll call you delusional. Mars crew transfer vehicles do not exist and will not exist for another 15 years at least. Show me those magical spaceships that can land people on Mars or those magical mobile labs that can support manned exploration sorties for several days. Robotic exploration, on the other hand, has existed for years, and in fact it has already returned more data than crewed exploration. Why? Because it's cheaper and more efficient, but also because dedicated tools like MER or Curiosity, with their array of instruments backed up by entire science teams, are actually much better at field geology than a single human with eyes, hands, and a hammer. And the fact the one exists whereas the other doesn't proves that it was also faster. The time imperative was won by robots decades ago. Manned missions have been in the works for decades with zero result. Self driving cars exist. Vehicles that can navigate through rough terrain exist. Computers that can prioritise and make decisions exist. AI advances faster than spaceflight technology. It's just a matter of iterative engineering to transfer those technologies over to robotic exploration, it's not magic. Each generation of space probe gets smarter and more autonomous, while it gets better instruments. Ideally though, you don't need a robot that can decide which samples to pick up. That sort of decision making is better done by a science team on Earth. What does benefit from autonomous AI is the actual navigation and driving or climbing over the terrain. So, all things equal, there is no scenario where a manned mission is faster, cheaper, safer or even higher quality, than a robotic mission. If you want to justify humans in space, you need to find another reason than science.

I see what you did there.

It isn't. Engineering uses science, but they are two different fields of work with different methodologies and purposes. So you are agreeing that the only thing can learn by sending humans to Mars is how to send humans to Mars. Now all you need is to find a reason to send humans to Mars in order to learn how to send humans to Mars. Circular.

Australia had a launch site at Woomera. There are still some ESA and NASA facilities there I think. But you'd be better off starting from scratch. Australia is big and desert enough to actually allow inland launches and first stage landings 200km downrange without flying over inhabited regions. However, I don't think they necessarily have launches in mind. An Australian Space Agency could just handle cooperation projects with other agencies.

G'th was specifically using the amount of rocks returned as a (quite arbitrary) yardstick for comparing robotic and manned missions. So geology is pretty much the only field involved. We were talking specifically about Mars, but even with your metric, I wouldn't be surprised if Voyager alone produced more papers than Apollo. If you add up all the unmanned missions from Pioneer to New Horizons, I'm pretty sure you'll exceed Apollo papers by an order of magnitude.

Again, who cares about time? We are talking geology. It's not magical. A robot is a tool that is used by a whole team of human geologists that can focus on a single area for years. They can actually do much better than a single human geologist who would focus on a wider area while dealing with staying alive and returning to his shelter ever few hours. Robotic probes exist. Manned expeditions don't. So tell me which one is magical. Show me how many Mars science publications have been produced over the past 30 years based on unmanned expeditions vs manned expeditions.

They can return much more actuallly. A crewed mission is limited to a radius around its landing site. It also has rest periods and has to spend a lot of its uptime for technical work just to stay alive. The actual science payload of a manned mission would be less than 10% of the mass and mission time. For the same cost, you can send dozens of robotic missions that cover the entire surface. Time is not a factor. There is no rush. The Genesis rock was already there millions of years before Apollo, and it would still be there if it hadn't been picked up. It doesn't matter if we pick it up today or in 20 years. We are talking geology here. There is no inherent reason why a robot can't go faster. The main reasons we design them to be slow are: So that whole teams of scientists can actually scan every single centimeter around the robot, making it a far more thorough analysis than a human walking around, worrying about his life support, stability, rest periods, and not stumbling over that rock and cracking his helmet. Because speed requires energy which requires mass which is expensive. If you gave a robotic mission the same mass budget as a manned mission, you could get a much faster and more complex robot. Robotic technology is advancing at a much higher pace than spaceflight technology. There is much more corporate investment in AI than in aerospace R&D. We already have self-driving cars, robotic durgeons, so there's nothing stopping you (except cost) from having a semi autonomous robot with much better decision making that Curiosity or the MERs for example. There is nothing complex about sample return. We've already done it. And returning thousands of kgs is pointless. What you need is variety. 20 years is pushing it for a single mission, but you can send 2 missions every 2 years for 10 years and get much more variety of results than a single 20 year mission. We haven't done sample return because no budget has been allocated to it, but there is nothing technically impossible about it. It could be done in less than 10 years, if the budget is allocated. Humans on Mars has always been 20 years away. A "series" of manned Mars landings would cost 100 times more than a series of robotic sample return missions. There is no inherent reason why the science would be better, but even if it was, would it be 100 times better ? The only science that only sending humans into space can do, is to study how to send humans into space. That's certainly valid, but it's a bit circular. The cost is absolutely crucial for anyone who understands how the government actually works. Call me a pessimist, I'll call you delusional if you think that the US Congress is going to abandon the military-industrial complex and lose hundreds of thousands of jobs.

The whole "repurposing Shuttle ETs" was always a bit of a myth. The ET would have needed a major redesign to actually use it for anything. You would need an airlock, attitude control, docking system, internal hatches between the tanks, removable baffles, etc, etc, etc... A lot of engineering that would make them more complex, heavier, and less reliable. Just leaving in them orbit, the orange foam would outgas, degrade, and end up as a giant cloud of orange debris around the tank. Yuck. The whole idea was utterly impractical.

We've already explained why that question is a non-starter. SpaceX can't do it without somebody paying for it. NASA can't do it without political support. When one of those is no longer true, then there will be factual basis to answer your question, instead of baseless speculation.

If you have something to contribute, then contribute. Otherwise, leave the thread alone.

You need something to "shuttle" crew, supplies, propellant, and equipment between the surface of both planets and the cycler. Call it an interceptor, a lander, an ITSy, or... a shuttle. Same thing. This sort of argument is bandied around a lot, with examples like Tang, the Space Pen, or Velcro, all of which are urban legends. In reality, most of the money spent on space ends up paying contractors, who employ workers, who buy stuff, etc... It flows back into the economy exactly the same way as military spending. One could even argue that military spending has advanced technology more than NASA ever did, with things like GPS or the Internet. You don't "lose" progress. Technology keeps advancing with or without Mars. One could argue that it's pointless to go to Mars today at a huge expense when technology in 10 years might make the endeavor ten times cheaper.

The RL10 has an extendible nozzle. It might be possible to design a retractable one too. Or you can do an aerospike version of Merlin.

I've been reading about Mars colonies since the 1970's. Landing on Mars has always been 20 years away.

The only point of a cycler is living space. Everything else (crew, supplies, propellant, and shuttle craft) needs the same amount of dV, plus you have to bring extra propellant for cycler corrections. The cycler itself would only have a larger ECLSS than the shuttle craft, power, and maybe propulsion (it could use the propulsion of the shuttle craft). Since the whole point of a cycler is that it's bug and heavy, it will also need a lot of energy for course corrections. I don't buy the "100 pax" capacity of the Musk's ITS project, but it can probably accomodate 10 or 20 people in relative comfort for a round trip to Mars. Once you want to start sending people by the thousands, then you have to calculate the tradeoffs between building a huge cycler and putting it into its orbit, or simply mass producing more ships. Maybe the latter makes more sense in that it gives you redundancy and mass production is cheaper than a one-off. Either way, getting that far depends on a whole lot of assumptions and hand waving at this point. This is so far in the future, that there is no point in speculating on the economics of a cycler, since we don't even know what the economics of this colonization effort are going to be.