Nibb31

I don't think it inspired them to make those technologies. Otherwise, we would have teleporters and warp drives. Things like laser weapons or mobile phones would have happened regardless of Star Trek.

You could pretty much rewrite any Star Trek episode by replacing technology and science with magic. It would work just the same.

I was considering near term technology this thread was about near-term technology that might be needed in 20 or 30 years. If we are going into Star Trek grade fantasy with orbital dry docks and vapor spray radiator material, then pretty much anything is possible, including 1G brachistochrone gravity. In that universe, a few tons of extra weight is the least of your troubles. For any interplanetary mission that we are likely to see in the foreseeable future, we are stuck with orbital assembly of modules that are built on the ground. I'm thinking more about The Martian's Hermes, 2001's Discovery or Nautilus-X technology than USS Enterprise or Battlestar Galactica. Anything built in a 1G environment and designed to be launched on a rocket is likely to be able to cope with a reasonable amount of artificial gravity in space without much extra weight. If we ever get to the point of star docks and asteroid mining, then technology will have advanced to a point where the discussion we are having today will be moot, so there isn't much point going there. Even if those systems are complex, you still want to avoid as many moving parts as possible. Anything that moves is going to produce friction, wear, and heat. Therefore it's simply more likely to cause problems.

Because reasons. Nautilus-X was a low-badget paper study without any actual engineering. It was as close to a real interplanetary spacecraft as the early Apollo designs looked like the actual Apollo, or the early Shuttle concepts ressembled the real Shuttle.

Weapons? Seriously? I thought we were talking about realistic designs. Slush isn't much of a problem once it's rotating. Just add some baffles in the tank, and the engines don't need to be running while you spln-up anyway. If anything, gravity induced ullage is a benefit. You also get the benefits of thermal regulation, and spin stabilization. For solar panels, radiators, thrusters, etc, you can either attach them to their own 3D Canfield joint, like this old CEV concept: ...or just a flexible joint that can absorb the load, like the solar panels on Orion: ... or you can just attach them radially to the outside of the spacecraft so that they double as MMOD shields. Hydrogen is pretty much a no-go for interplanetary missions, because boil-off. The Apollo stack used "barbecue roll" spin on its way to the Moon, not for gravity but for thermal regulation. The fuel consumption to spin up Apollo was negligeable compared to the size of the spacecraft. I don't see why it wouldn't scale gracefully to a larger vehicle. You could even use SEP thrusters to do it on a larger craft. And the induced spin stabilization actually saves propellant used for attitude corrections. You know what would make everything heavier? Joints, connections, seals, motors, and everything needed for a spin section. It would also make everything more complex and more failure prone. What happens if it jams? What happens if it leaks? What happens if you run out of lubricant?

You don't say ! It certainly serves the purpose of avoiding using special effects to simulate zero-g when filming the crew. In real life, I doubt we will ever see rotating sections on spacecraft. They wlll either deal with zero-g through medical methods or spin up the entire spaceship using a barbecue roll or a tether.

That's an old article that has already been mentioned several times on these forums. It gives a glimmer of hope, but by most accounts, it would not have been possible in the end. The plan described in the paper relies on zero defects or delaying issues in the processing of the rescue orbiter, which simply never happened throughout the whole program, and cutting corners to go faster would only make things worse. Secondly, there was no way for the two vehicles to dock, and manual station keeping during the time necessary for the rescue operation would have exhausted the RCS fuel in both orbiters. I suggest reading the actual CAIB report, available here: http://www.nasa.gov/columbia/home/CAIB_Vol1.html

Isn't the Hermes reusable? I don't think the capsule at the front reenters. I would think that they dock at an EML gateway and return on an Orion-like vehicle.

The ship is pretty realistic, if you take into account the magic propulsion. In reality, major part of such a vehicle would be tankage, even if it had SEP. Also, it would probably need more solar panels. The rotating section is unnecessary, but people have become accustomed to the idea that spaceships need a rotating section for artificial gravity. The movie doesn't detail the actual mission architecture. It seems like the MAVs and maybe some cargo landers are prepositioned before the arrival of the crew, so we can assume that they use some other vehicle for cargo and MAV delivery. We also don't know what the crew uses for landing or whether that vehicle is prepositioned in orbit or if the Hermes carries it along.

No. You'd end up with a dead core stage in orbit and two boosters burning up in the atmosphere. The F9 Core stage is not a spacecraft. It's not designed to go to orbit or to reenter from (near) orbital speed. It doesn't have power, avionics, insulation, or attitude control to do anything useful in space.

It's likely to cause other issues due to the Coriolis effect, including problems with the inner-ear.

When New Shepard is at the top of its apex, by definition, its speed is practically zero. If you were to release an upper stage at that point, the stage would still have to carry 7 km/s of dV to reach orbital speed. Basically, it would be just a glorified air launch. Staging events occur when the rocket is at its peak velocity, which for New Shepard doesn't exceed Mach 3 and at a much lower altitude than the 100km apogee. Falcon 9 stages at approximately 100km altitude, but it's going at Mach 10 (expendable) or Mach 6 (recoverable). The upper stage only has to handle ~4 to 5 km/s. I'd like to see a 2 ton rocket that would have 7 km/s of dV. The Ariane or Start upper stages have nowhere near that capability with or without any significant payload.

The final approach takes several hours. https://www.youtube.com/watch?v=MNe577ttvfw

Apparently, one of the biggest problems is intracranian pressure and optical nerve deformation.

cable, fiber, and 3G/4G coexist mainly because they are operated by the same companies, and they cover 95% of the population. I don't know what it's like elsewhere, but here in France, ISPs and cellular operators merged a long time ago and our telecom prices are among the lowests (~20€/month for unlimited 3G/4G and ~30€ for unlimited internet on ADSL or fiber, and you can get joint deals that combine both for even cheaper). This is because there is an extremely competitive market. The reason prices are higher elsewhere is probably because those telecom companies have higher margins. if you introduce another competitor, you would see prices go down and service go up to align themselves. In the end, I see some people preferring satellite internet, but in populated areas where people have a choice, they will go with the lower price or better service (and 5G is coming soon...) I guess this is where every national market is different, with different legal and competitive requirements. That means that a constellation operator would either have to set up a sales infrastructure in each country, or have to partner with an existing operator. In any case, the competition will be fierce It also turns out that existing satellites often operate as a backhaul service for the consumer-oriented companies mentioned above. If SpaceX goes head to head against them, there is a chance that those companies will start buying their launch services elsewhere, which could hurt SpaceX's revenue stream.

With the advances in space biology, we don't even know if artificial gravity is even necessary for the foreseeable future. For all we know, we can fight bone loss with medication and exercice. We've proven that people can live on the ISS for over a year. By the time we ever need long duration spaceflight, we might have pushed that limit to two years or more... But even if it is necessary, why bother when you can rotate the whole spacecraft. You're going to introduce a whole slew of fragile parts that need replacing and maintenance (seals, lubricants, etc...), along with a whole bunch of new failure modes. I know it looks cool (like wings on a spaceship), but rotating segments are just another solution looking for a problem. Keep it simple !

SpaceX has gone quiet about their constellation. There are at least two possible reasons for this: Their main customers are in the communication business, and they don't want to upset them. Currently these folks are customers. If SpaceX becomes a comsat operator, then they become direct or indirect competitors, which means that they are likely to lose a lot of business. They have done the math on their business plan and the ROI analysis has shown that the comsat business is too competitive, that the margins are not as high as they expected, and that there isn't as much money to be made as they originally thought. LEO comsat constellations have been tried before, but in the end, they are a niche for some very specialized applications. Going head to head against the established ISPs and cable and cellular operators in the consumer market is bound to be a tough struggle. Those companies (which are often backed by governments) have spent decades investing in infrastructure and they will not give up without putting up a fight. Musk originally envisioned the constellation as a cash cow that was going to pay for the Mars stuff. Maybe they have found out that there isn't really that much money in that particular market, and that the drawback of upsetting their current launch customers might not be worth it. Musk is a pragmatist. He's very vocal when he has an idea, but sometimes those ideas don't work and he drops them when he realizes it.

This is exactly why rotating hubs are a bad idea. It's much easier to simply rotate the entire vehicle.

The ISS isn't used for routinely launching satellites. They sometimes eject something like a science cubesat, or the SuitSat, and you're right, it ends up on pretty much the same orbit as the ISS. However, they typically do this before a reboost so the experiment decays due to drag and the ISS is boosted to a higher orbit. Gravity was unrealistic because satellites are typically in different inclinations. Altitude is not much of a problem, but different inclinations require a plane change, which requires a lot of dV. Hubble was in a completely different orbit to the ISS, so there was no way they could have rendezvous'd with the ISS with the dV of George's MMU.

No, but 10 rovers that cover the same distance 12 hours a day over 5 years are going to give you a wider variety of samples than a single human stumbling around a limited area for 2 hours a day for 6 months. You are underestimating how hard it was for the Apollo astronauts to move around. Don't be fooled by the weightlessness. The lunar EVAs were exhausting, and one of the major concerns was that if an astronaut actually fell over, they would have a hell of a time getting up. The regolith being abrasive was a major concern too. Yes, robots are slower, but 1) they don't have to be, and 2) who cares if they are slow. Mars isn't going anywhere and there is no rush. We have latency on Earth when you have engineering teams split up between various countries in different time zones. You send instructions and get the results the next day. As long as the robot has enough AI to avoid putting itself in danger, it's no big deal. We can handle it. Sure, it would be nice to get the results faster, but is that speed worth paying 1000x the price if you get the same results in the end. FFS, we already know about Zubrin TYVM. There's no point in posting it again and again, especially the 1991 paper which has been dismissed even by Zubrin himself as overly optimistic. Zubrin cooperated again with various Mars DRMs, which have all ended up being both too big to be sustainable and too optimistic at the same time, which is quite an accomplishment. Don't worry about that, I'm used to it

Rubbish. Heat is the least of your worries. On Mars, the air isn't breathable. The soil is toxic. There is cosmic radiation and low gravity. You rely on technology just to be able to breath and get drinking water. And you 6 months away from any supplies. It's orders of magnitude harder than surviving in Antarctica. We don't know how difficult getting water from Mars is. Then you have to purify it to remove all the perchlorates and then you have to add the minerals that we actually rely upon to live. Those minerals have to come from somewhere, so do the consumables, chemicals, and other supplies. And if any of that water supply chain breaks down, you're dead. You said yourself that the atmosphere is extremely thin. That actually means that sandstorms are not that huge and that you can't rely on wind for power. It's going to have to be solar or nuclear.

If you take Musk's timelines for granted that is.

Because it's faster to fuel up and launch an ICBM than to wait until your orbital platform is over the target to deorbit a nuke. And an orbital nuke launcher isn't really stealthy.

No, for Commercial Crew, parachutes are the primary landing system. They will always be the primary landing system for pad abort landings.

You are saying that you need 8 parachutes in case 4 of them fail. Parachutes are heavy, so this represents a lot of extra weight. And if 4 independent parachutes fail, then it's not an outside cause, it's a design flaw that is likely to affect all the parachutes. Simply adding more parachutes will not solve the design flaw, it just adds extra weight for no safety benefit. That's why in engineering, you don't provide redundancy of safety systems by simply duplicating the systems. It's usually better to provide alternative ways of activating the safety systems or integrating a secondary backup function into other systems. For example, you can use RCS to deorbit if your main engine fails.