Nibb31

Solar panels can last longer than 20 years, but their production decreases. The estimates were around 1% per year, but it is now closer 2%. They suffer quite a lot from MMOD. Assuming that the degradation is linear, by 2024, the oldest panels will be producing 70 and 80% of their initial rating, which means that some systems, mostly experiments, will have to be powered down. Sure, you can replace systems and add more panels, but how much are you willing to spend to maintain old equipment? It's just like for an old car. At one point it becomes more economical to scrap it and buy a new one rather than to keep on repairing it. As I said, even if a commercial acquirer got handed over the ISS for free, the maintenance costs are $2 billion per year, and they will only increase as the station gets older, so you would need to have a heck of a business model to keep it running. Oh, and Russia isn't going anywhere with their station. Roskosmos' budget just got the axe, so there will be no new modules, no PPTS, and no new rockets for them...

No, you discuss. If you post a new thread, then you must have something to say about the subject. If you haven't, then what's the point in posting.

I don't think so. Look at locomotion for example: a bipedal robot has more single failure points than a 6-wheeled chassis. It's also less stable, meaning that if it does fail, it can fall down and damage its payload, whereas a wheeled platform will remain stable and can still work as a fixed station. And the same is true for arms. Why go with only two arms. Why not four or five ? Why use an imitation of the human hand when you can design a claw that fits much better onto those EVA rails, and a purpose-built electrical/mechanical interface for tools.

Well, the same was true for "Robonaut 2". Sending a humanoid robot to the ISS was a cool PR stunt, but it's been pretty much collecting dust and taking up space ever since.

The end-of-life date that is often mentioned is around 2024. By then, most of the hardware on board will be much older than Mir was when it was abandoned. The solar panels will only be producing enough power for the most vital systems. Seals, gaskets, filters, fluids, will need replacing in a lot of non-serviceable systems, meaning that the whole systems will need replacing. Also, even if the US sells off the USOS, that will not cover the Russian segment or Columbus and JEM. Many systems are intertwined, so you can't just disconnect the Russian segment and expect both sides to fly independently. There would need to be a lot of work, including EVAs, to deconstruct stuff that has taken decades to construct. So buying the ISS, even for $1, will still cost the acquirer a LOT of money, just to get it back into shape and to keep it flying. It really isn't worth it. They would be much better off launching a brand new station, purpose-built for whatever purpose they want.

It's because it's NASA, and everything NASA does these days has to be tied to Mars some way or another. A humanoid robot makes sense if it's designed to use tools and vehicles that were designed to be used by humans. Other than that, anthropomorphic robots are a silly idea. The human body isn't some sort of universally perfect form. It's more often a compromise that performs suboptimally for most specialized tasks.

As usual, define "better". Different systems are different answers to different requirements, different problems, and different industrial, economical, and political environments. So what are you criteria for determining which is "better".

Define "better"

Your questions are a bit too specific. Either they answers aren't public knowledge or they would need a lot of calculation to answer.

Always has been, and always will be, the Mighty Mini The real thing, not that 2-ton BMW monstrosity.

This article is interesting and explains everything: https://en.wikipedia.org/wiki/Space_Shuttle_thermal_protection_system

LauncherOne is not carrying passengers. It's a small satellite launcher.

2. RCC panels were only used on the wing edges and the nose. They did not need replacing. In fact after Columbia, there were no spares that could be used for testing so they had to cannibalize the RCC panels from Enterprise. 3. SpaceX Dragon uses PicaX, which is supposed to be reusable. The Shuttle used 3 different TPS materials depending on which part of the shuttle it was on. 4. The SSMEs were removed and rotated so that they were mixed around and assigned to different orbiters. This was because the servicing cycle was longer for the engines than for the orbiter.

Yes, but they aren't using a 777, they are using a 747. I don't know why you keep on insisting on a 777.

Any life would be fried by the radiation, so the Earth would be as barren as Saturn's other moons.

You can't fly from any airport, because most airports that are large enough to handle 747s aren't equipped to store and handle rocket fuel.

Yeah, but Virgin already has a bunch of old 747s, as well as maintenance crews, spare parts, etc... Also, they are using a hardpoint that already exists on 747s for ferrying spare engines: This means that there is no heavy structural work. All in all, this should be cheaper than buying a new plane. But in the end, it's all a lot of complication for nothing. The gain in dV is negligeable. Since they are designing a rocket from scratch anyway, they might as well ground launch it and do away with the air launch altogether.

And where exactly would you hang a rocket underneath a Boeing 777 ? The Concordes have all been retired. Their flightworthiness certificates have been revoked and any spare parts have been sold off and liquidated. It's quite ironic that Stratolaunch is looking for a rocket for their plane, and Virgin Galactic is looking for a plane for their rocket, yet they seem to be ignoring each other. Air launch is not about ceiling. It's not about speed either. Actually, it's a false good idea, and I think neither of them are going anywhere.

When a government subsidizes the private sector, it doesn't mean that they don't expect a return on investment. The money that the DoD poured into Falcon 1 development far exceeded the utilisation that was made of the Falcon 1 afterwards. The same is true for Falcon 9 and Dragon, where NASA paid for the development as part of the COTS program, but SpaceX is free to sell both products on the private market. One could argue that the commercial use of those products is subsidized in the same way that Ariane development is paid for by ESA member states but launches are sold as a commercial service. The main purpose of many US Government cost-plus contracts, particularly DoD and NASA, is to provide jobs to the military/aerospace industry, regardless of the actual value of the product or service to the nation. The point of that is to maintain jobs, boost technology, and maintain capability, more than to actually pay the fair price for a given service. It can be argued that any government contract represents a form of subsidy. However you call it, it isn't very important. My point was that all spaceflight is government-sponsored, whether it's subsidized or purchased at a fair price, and that there would be no orbital space industry without that government sponsorship.

VentureStar was never funded. X-33 was. I think that DC-X had more potential, but NASA didn't want it because it wasn't invented here. Interestingly, many Lockheed-Martin folks who worked on DC-X are now at Blue Origin.

And what BO did was a lot more challenging than what SpaceX did with Grasshopper.

SpaceX only wins if they make it profitable to reuse a landed stage.

Government subsidies: Since its inception, SpaceX has relied on government contracts. The Merlin engine is based on a NASA reference design. Falcon 1 was funded by the DoD. Falcon 9 developmend was co-funded by NASA and private funds. Dragon was funded by NASA. SpaceX is profitable today, only because of those contracts. If they had relied solely on private funding, they simply would not exist. However, all of that government funding was part of commercial contracts. Whether you count it as subsidizing or not depends on how you interpret things, and if the price paid was proportional to the benefit to the taxpayer. It can be argued both ways, so I won't take sides here. The fact is, without NASA and DoD contracts, there would no private space industry in general and no SpaceX in particular. The same is true for the European, Japanese, Russian, or Chinese space industry too. Reusability: Cheap spaceflight through reusability has been the holy grail of the aerospace industry since the end of Apollo. SpaceX wasn't the first to envision reusable rockets and won't be the last. The challenge never was technological. It has always been economical. Reusability only makes sense if you have high enough flight rates. Increasing flight rates does not depend solely on bringing costs down. It depends mainly on finding a purpose for those flights. SpaceX has a high probability of finally achieving first stage recovery and reuse. That will be a great technological accomplishment, but let's remember that the goal isn't to recover or reuse stages, it is to bring costs down. Recovery and reuse do not automatically bring costs down, nor are they the only ways of bringing costs down. Ultimately, what will bring costs down is to increase flight rates in order to generate economies of scale. Orbital launches are expensive because they employ lots of people to manufacture, test, handle, integrate, transport, and launch the rocket, but also to build payloads and ground stations, integration, fueling, handling, mission planning, mission control... There are also infrastructure costs, administrative overhead costs, facilities, power, IT, HR, training, legal, catering, etc... The result is hundreds, if not thousands of highly qualified people, working in the aerospace industry. The biggest cost factor is not the first stage hardware, it's the payroll of a particularly expensive workforce. Recovering the first stage is not going to automatically reduce costs by 50% (or even 20%) unless it allows to fire 50% of the workforce. It only has the potential to save some of the manufacturing costs, the rest of the costs remain constant. SpaceX has invested in facilities that can mass-produce Falcon cores. This means that if reusability comes into full swing, those facilities will be underproducing and the cost of each stage will actually increase due to the lack of economies of scale, which might negate the whole reusability business model. This is why the competitors of SpaceX (ULA, Airbus, etc.) are in "wait and see" mode. They have their plans to incorporate reusability into their business models if they need to, but they are mainly waiting to see how the market reacts to SpaceX and if SpaceX can actually make reusability profitable before they decide whether it makes economical sense to commit to it.

I'm getting bad vibrations from this. Partnering with the Russians on a Mars probe is like going to a stag party with this guy.

I don't think it is. I think they have got the approach targeting figured out pretty well, so there isn't a huge risk of the rocket crashing somewhere it shouldn't be. The failures have been on the dynamics of the ground contact, which are more complex on a moving platform than they will be on a proper landing pad. I'm pretty confident that the chances of a successful landing on terra firma are higher than on a barge. If they go with a landing at LC-1, I'm quite optimistic that they will finally nail it.