Nibb31

It's one and the same on satellite busses. The 4 ion thrusters are used for propulsion and station-keeping. It typically takes the 702SP 5 months to reach its GEO orbit instead of 3 or 4 weeks for a bipropellant satellite, but it is much smaller and lighter, which cuts launch cost.

How come this silly thread deserves to be stickied?

Yep, one of the most annoying tropes is that UFOs are always assumed to be of extraterrestrial origin. Just because they are unidentified and unexplained doesn't mean they aren't from here. There is as much chance of an unidentified phenomenon being extraterrestrial as of it being from the distant future, Soviet or CIA secret mind-control projects, a parallel universe, some unknown terrestrial species, ghosts, an act of God, leprechauns, or rainbow-colored unicorns. In fact, the chances of a UFO actually being from outer space are pretty remote and far-fetched compared to the other wacky explanations.

Tell that to Boeing. http://www.boeing.com/boeing/defense-space/space/bss/factsheets/702/702SP.page?

ISRU requires mining equipment, extraction equipment, crushing equipment, processing equipment, tankage and refueling equipment... All of this is heavy machinery that has to be rad-hardened, vacuum hardened, temperature tolerant, automated, and zero-maintenance. A test stand with the theoretical processes is a great first step. Automating those processes in a package that can work autonomously on another planet with life-depending reliability is a huge technical challenge. You need to get everything right the first time. We are talking about a level of magnitude more complexity than the wheels of Curiosity for example. The TRL for ISRU as around 2 or 3 at this stage. For humans to be able to solely depend on it to return from a real expedition, it needs to be TRL 8 or 9, and it needs some form of redundancy. To get there will take many years of engineering and precursor missions to validate the technology.

Not your idea. NASA already had it in the 60's. It was called MOOSE:

Elon Musk's approach to Mars is very different from Zubrins, and even more delusional. What he has done with SpaceX is admirable, and he is a visionary, but self-sustaining colonies on Mars in this century with thousands of emigrants buying tickets to live there? No way. NASA's DRM approach uses orbital assembly of multiple vehicles, and precursor cargo landings, which is similar to Zubrin's. However, Zubrin's Mars Direct is more minimalistic and a bit reckless. It relies on ISRU, which is great as a long term goal, but not mature enough to risk astronauts lives on. It also implies tether-based artificial gravity, which adds unnecessary complexity. Personally, I don't get the point of a manned expedition on Mars at this stage. The technology is simply not mature enough, and it will take decades to develop and bring up to a usable TRL. During those decades, we would be doing nothing. I would rather see NASA concentrate on doing stuff that it can afford, with goals that are reachable today. If that means sticking around LEO and the Moon, then so be it. It might not be as spectacular as Mars, but I'd really want to see some actual achievements rather than another 30 years of powerpoints and youtube videos.

Zubrin is a bit delusional. Although his ideas are popular and make spectacular pictures, nobody in the space industry really takes his obsession with Mars seriously.

As I said in one of the previous posts, these long duration bed rest experiments are nothing new. NASA and ESA have been conducting them routinely for many years with hundreds of test subjects without any long term health problems. The following paper has a pretty good description of one of these tests conducted in 2009: http://prtl.uhcl.edu/portal/page/portal/SCE/Natural_Sciences/NS_Documents/Reprints_Cromwell_Talk.pdf During this test, subjects got visits and phone calls from NASA astronauts and even got to chat with ISS crewmembers in orbit. They had access to entertainment, family visits, psychological support, etc... There were also regular followup exams during a year after the bedrest period. It's a very interesting read and demonstrates that the folks conducting these tests are not reckless idiots. If you google "long duration bed rest experiment" you'll find plenty of other papers on similar tests, because as I said earlier, these have become pretty routine in medical space research. As more of these tests are conducted, and knowledge of the conditions is improved, any durable health risks are increasingly reduced.

Comparisons of hourly wages make no sense. It's an experiment. You do it for science not for money. Do you think NASA astronauts get paid for 24 hours work on the ISS? Or researchers at Scott Amundsen Base ? Submarine crews ? Soldiers ? Oil rig workers ? Truck drivers ? Most of those workers would be happy to get $18000 for a two month mission. Just because you don't get to sleep at home every night doesn't mean you work 24/7. You guys are just being ridiculous.

I honestly don't think it's that dangerous. The subjects are under constant medical supervision so the yet can be interrupted immediately before it gets dangerous, and they will certainly be followed and treated for any effects after the experiment. The return to "normal gravity" is a major part of the research.

That's just ridiculous. Public and private medical research employs paid test subjects on a regular basis. Are you guys just discovering the practice? How do you think vaccines, medicine, and cosmetics are developed? How do you think medical research is done without testing and comparing on a panel of test subjects? As for highly paid/highly qualified employees, aren't they better put to use on work that requires those high qualifications they are paid for?

Yet short of getting hired as an astronaut, this is probably the closest you can personally get to be part of the space program. But never mind, there is no shortage of volunteers for this kind of experiment. It's probably just not for you. The effects are well known. This sort of experiment is a way of testing and comparing new treatments in a controlled environment and establishing medical protocols on a wider and more accessible group than the astronauts that are up there doing other work. This allows the medical corps to monitor and examine the subjects constantly in a way that can't be done on the ISS and on a wider panel of subjects. It also allows them to try things that might not work without endangering the lives of the astronauts or impeding their work.

The study is to find ways to prevent bone loss and other health problems. The participants are monitored by medical teams 24/7 and follow special treatments before, during, and after the 2 month bedrest period. They don't just kick them out after two months without dealing with any problems. Also, people don't do this just for money. It's a way to help science and improve our understanding on how to live in space. It's funny that this forum is full of space cadets that want us to build cloud colonies on Venus or interstellar warp drives, but when offered the opportunity to actually do something that really helps space science, the biggest criticism is that it's not paid enough.

ESA does thes experiments on a regular basis, with people lying down for 60 days: http://www.esa.int/Our_Activities/Human_Spaceflight/Research/Lying_down_on_the_job http://www.cnes.fr/web/CNES-en/10592-st-2012-experience-d-alitement-prolonge-au-medes-a-toulouse.php

So was Soyuz, but then the Russians turned it into Zond and LOK. Shenzhou is modular, efficient, proven, and safe. To turn it into a lunar vehicle, you would only really need a modified service module, but there is no reason why they wouldn't keep the orbital module and just stick a beefier heatshield on the descent module, especially now that Change'e 5 has proven that it works for lunar re-entry.

Or maybe those promising projects were cancelled because it became clear that they were dead ends or not viable. It's funny how it's always the "promising projects" that are cancelled. Those rocket scientists must be idiots. Without government funding, there would be no spaceflight at all. The only vaguely viable activity for the private sector is comsats, and even that is because the launch vehicles are heavily subsidized.

Typical space cadet thinking: Solution => Problem. How things work in reality: Problem => Solution. This is the issue I have with most wacky space colonization ideas. People grasp at straws to find justifications for a complicated technical solution that they really want because it looks cool and science-fictionny, even when that technical solution doesn't solve any actual problem. First start by identifying a problem. Then figure out the various ways to solve that problem and select the easiest/cheapest/most beneficial solution. If the best way to solve that problem is to colonize Venus with cloud cities, then go ahead and figure out ways to do it, but I can't think of a single problem that this solution solves that can't be solved by much easier/cheaper/more beneficial means. If the problem is access to asteroids, there are easier ways to do it. If the problem is overpopulation, there are easier ways to solve it. If the problem is access to rare ressources, there are easier ways to get them on Earth. If the problem is to find ways to explore Venus, then I think that repeating and improving on the Venera-Vega mission architecture is probably a good idea. But there is absolutely no viable reason to send people to Venus at this stage.

Rather than design a new spacecraft for lunar exploration, it makes more sense to simply modify Shenzhou to extend its capabilities. The Chang'e 5 sample return capsule is clearly a scaled-down Shenzhou capsule. Although it's too small to carry astronauts, it also seems way oversized for just bringing back a few soil samples from the lunar surface. To me, it's clear that the main purpose of Chang'e 5 is to test lunar manoeuvers, docking and lunar reentry for a future manned capsule. There has been a lot of activity around the Moon recently. I wonder if they are actually shifting focus away from their space station program and towards lunar activity. A lot of their PR these days is about robotic exploration of the Moon and Mars rather than on manned spaceflight. It's also not impossible to imagine that their space station could be used to support lunar exploration, similar to what Russia is planning for OPSEK.

The French submarine Surcouf, one of the most fascinating ships of WWII: Surcouf was the largest submarine in the World at the time, with 12 torpedo tubes, a 5 meter motorboat, two 37mm AA guns, twin 203mm (8 inch) guns and even a pressurized seaplane hangar. She was so big that she was categorized as an "underwater cruiser" in the French Navy nomenclature. Surcouf was in drydock when the Germans invaded Brest in WWII, but the crew managed to get her out to sea at night and surface-sailed to England on a single electric engine, where she was captured by the British Royal Navy alongside the rest of the French fleet. The British weren't keen on keeping her, because of the lack of spare parts and trained sailors, so she was handed over to the French Free Forces where she served in the North Atlantic. She was lost at sea in 1942 near Panama Canal. The official story says that she was rammed by a cargo, but it seems more likely that was sunk by friendly fire from an American PBY Catalina that mistake her for a Japanese or German sub.

You need more than a legal waiver to rebuild the hardware. None of the existing LKs are flightworthy.

L4 ? You mean EML-1 or EML-2. The Trojan points EML-4 and 5 aren't very useful.

It wouldn't. You would need to redesign, retest, and requalify that old hardware with modern materials, manufacturing techniques and safety/environmental standards. It would be easier to start from scratch. What we really need is a reusable lunar lander that would remain in LLO or at EML-1 or 2 waiting for a visiting craft. That's the best way to provide assured access to a base on the surface. For example, a visiting Orion CSM+EDS would dock with the lander, undock from the EDS, turn around and redock the lander to the EDS, undock from the Orion. The lander would use the EDS as a descent/crasher stage (like the old LK) and to refuel the ascent stage.

Radio or laser signals all travel at the speed of light. Long distance laser communications might provide a higher data rate, but that is still experimental at this stage. The problem is the latency, not the bandwidth. It's already a problem with GEO comsats that are at an altitude of 36000 km. The round trip takes about a second, which makes them unsuitable for full duplex applications. The theoretical distance between Mars and Earth varies from 50 million to 390 million kilometers, which gives you a latency from 3 minutes to 21 minutes. And of course, when Mars and Earth are occluded by the Sun, then you have a communication blackout, or you would need to relay through another planet, which would give you an even higher latency.

Irrelevant. The media does not choose science missions. NASA is not an entertainment agency. Science missions are decided by science committees based on funding that is attributed to each agency by Congress. Russia is massively investing in Angara and the Vostochny cosmodrome. That is a huge investment in infrastructure that opens many doors for future missions. We've already given you X reasons why Mars is closer than Venus in terms of an exploration roadmap. You're just ignoring them because you are biased. All evidence suggest that it is easier to land on a solid surface than on an ocean of clouds. We simply haven't done that sort of thing before and it simply can't be tested on Earth, because the atmospheric chemical, density, pressure, temperature and wind conditions are totally alien. We can "survive" in just about any environment, as long as we can maintain livable conditions inside a pressure vessel. We can survive on the Moon, at the bottom of the ocean, or inside a nuclear reactor if we have big enough shielding and life support. But does it make sense to actually want to "live" in those places? Not really. Colonies on Venus make no more sense than colonies on Mars. The rest of your post about mining thriving colonies is just science fiction with no economical basis. Exploitation of resources on Venus is only meaningful if you are exporting those resources somehow, which is only possible if it's cheaper to get those resources from Venus than it is to get them from Earth. I don't think that the current demand of sulphuric acid is enough to jumpstart a Venus colony.