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Space Travel, 10/04/1957 - 10/04/2017


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9 minutes ago, Bonam said:

Just hope the Ariane 5 carrying it doesn't blow up on launch!

 

They've been very reliable. But...indeed. The first Ariane 5 exploded, of course.

A lot depends upon a red wheelbarrow...

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High altitude radiation is a dirty little secret with airline crews, especially on polar routes. I'm thinking it will be a big factor in long duration space travel.

Actually, space travel has consumed far fewer resources and done far less damage to the "natural" than mining, forestry, and commercial fishing.   Resources in space provide lots of data and imaging o

All the folks whining about the rich and powerful will still be sitting on Earth whining about the rich and powerful. Meanwhile, those who have something useful to contribute will become a spacefaring

One unintended consequence of space flight has been the willful pollution of certain parts of the Asian continent by Russian booster parts carrying toxic fuels falling back to the ground after separation. The Proton is the WORST. It uses hypergolic fuel. But the R-7 leaves quite the mess as well...kerosene. 

https://en.wikipedia.org/wiki/Proton_(rocket_family)

https://en.wikipedia.org/wiki/Dinitrogen_tetroxide

https://en.wikipedia.org/wiki/Unsymmetrical_dimethylhydrazine

Edited by DogOnPorch
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I watched a program on Netflux about building a space elevator.  There are some who believe that the technology will exist within the next 30 years, maybe less.  They're working on a strong fiber or material to use.  The whole thing sounnds ridiculous, but here's the thing: chemical rockets are very inefficient for getting people into space.  Only a handful of people, and cargo, at a tiime, with a price tag that goes into the millions for every rocket/capsule, more crap floating in low Earth orbit, and other effects of chemical rocket launches.

No way we'll become a truly spacefaring society until we can get at least several thousand people (differnt people not just the same over and over again) off the surface of the Earth each year.

IN the meantime, they need to develop reusable space planes, smaller than the Shuttle (which was extremely gosh darned expensive) that can take off horizontally, that don't leave any of the aforementioned crap floating in orbit.  That would be a helpful first step.  Then some more technology directed at self-sufficiency for a lunar or martian colony.  Can't keep going back and forth to Earth every time you need more Tang.

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3 hours ago, JamesHackerMP said:

I watched a program on Netflux about building a space elevator.  There are some who believe that the technology will exist within the next 30 years, maybe less.  They're working on a strong fiber or material to use.  The whole thing sounnds ridiculous, but here's the thing: chemical rockets are very inefficient for getting people into space.  Only a handful of people, and cargo, at a tiime, with a price tag that goes into the millions for every rocket/capsule, more crap floating in low Earth orbit, and other effects of chemical rocket launches.

No way we'll become a truly spacefaring society until we can get at least several thousand people (differnt people not just the same over and over again) off the surface of the Earth each year.

IN the meantime, they need to develop reusable space planes, smaller than the Shuttle (which was extremely gosh darned expensive) that can take off horizontally, that don't leave any of the aforementioned crap floating in orbit.  That would be a helpful first step.  Then some more technology directed at self-sufficiency for a lunar or martian colony.  Can't keep going back and forth to Earth every time you need more Tang.

 

This concept is explored in detail using Orbiter. Several space planes are available that use both SCRAM and rocket power to achieve orbit.

http://www.alteaaerospace.com/

There are also versions that put the space plane atop a booster for the ride-up.

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4 hours ago, JamesHackerMP said:

I watched a program on Netflux about building a space elevator.  There are some who believe that the technology will exist within the next 30 years, maybe less.  They're working on a strong fiber or material to use.  The whole thing sounnds ridiculous, but here's the thing: chemical rockets are very inefficient for getting people into space.  Only a handful of people, and cargo, at a tiime, with a price tag that goes into the millions for every rocket/capsule, more crap floating in low Earth orbit, and other effects of chemical rocket launches.

No way we'll become a truly spacefaring society until we can get at least several thousand people (differnt people not just the same over and over again) off the surface of the Earth each year.

IN the meantime, they need to develop reusable space planes, smaller than the Shuttle (which was extremely gosh darned expensive) that can take off horizontally, that don't leave any of the aforementioned crap floating in orbit.  That would be a helpful first step.  Then some more technology directed at self-sufficiency for a lunar or martian colony.  Can't keep going back and forth to Earth every time you need more Tang.

1. Space Planes

Bad idea. When it comes to getting things into orbit, you pay for every kg, there's no way around it. A plane has a whole lot of mass that is not necessary to be in space - wings, landing gear, the shape of the body, etc. All that weight is useless in space. Reusability is good, but space planes are not the way. Now that the technology exists for rocket stages to land back down vertically, that's a much better solution. 

2. Space Elevator

I actually did some work on this back in the day. Technologically, the tether material is only one of the issues to be solved. Carbon nanotubes potentially have the needed strength, though making a long carbon nanotube tether with bulk properties that are anywhere close to the small-scale properties of a nanotube remains a problem.

Besides this though, the entire space elevator tether needs to be able to dodge or withstand space debris. Even a few mm size piece of space garbage could slice the tether in half if it hits it. Accurate tracking of all the millions of pieces of space debris down to that size is nearly impossible. Alternately, you could try to clean up all the space garbage before putting up the space elevator - but that too would be a giant effort. Some research has been done on that but it's not easy - plasma clouds, laser beams, giant magnets, etc, have all been considered but none of these are ready for prime time. Making the tether mechanically robust enough to withstand impacts isn't an option since then the whole thing would be monstrously heavy and cost trillions of dollars. You could try to shield the structure with a plasma cloud, but again, lots of R&D work to do there. 

Besides these technical challenges, there are also geopolitical challenges. A structure going from the Earth's surface into space would fall under all kinds of international treaties. The public would have all kinds of safety concerns, both rational and irrational. A lot of people would be opposed on a religious basis. And of course the thing would be the juiciest terrorist target on the planet. 

Personally, I think we should build a space elevator on Mars before we build one on Earth. Here's why:

1) Mars has the same rotation period as Earth but much lower gravity. That means you don't need as strong a material to build the space elevator. Existing tether materials are strong enough for a Martian space elevator.

2) There's almost no space debris to worry about - we haven't polluted Mars orbit nearly as much as we've polluted Earth orbit.

3) The hardest part about Mars missions is actually landing on Mars. Unlike Earth with its thick atmosphere where you can use the aircraft body and then parachutes to bleed all your speed on re-entry even for very massive spacecraft, the Martian atmosphere is too thin. Aerobraking can only bleed part of your speed when going to Mars and parachutes are impractically large to slow down a heavy payload. Hence NASA's airbag landings, rocket-powered sky-cranes, and of course the failure by all other countries to ever successfully land anything there. A space elevator would make it much easier for cargo to get down to the Martian surface. It could also be used as a slingshot to send stuff on a return-to-Earth trajectory essentially for free. 

4) Building it on Mars avoids all of the political issues and keeps it far away from the reach of saboteurs and terrorists. 

5) Demonstrating a working space elevator system on Mars will increase the incentive to build one on Earth - once the practical benefits are realized and a functional system is demonstrated, it will be a lot easier for companies or governments to consider undertaking the much costlier and more complex problem of an Earth space elevator. 

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Re: Mars

There's ALREADY a space station in LMO waiting for us. It's bloody huge, too.

https://en.wikipedia.org/wiki/Phobos_(moon)

Easy target (low eccentricity: 0.0151) with multiple launch windows a day from the equatorial Martian surface (1° off-plane). Only 2.76 Mars radii distance! 

Seeing Phobos's orbital plane & period...you can forget your Martian space elevator, btw. 

;)

Edited by DogOnPorch
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Deimos will be handy, too...a bit further out. Even lower eccentricity (0.00033) and also within 1° of Mars's equator.

https://en.wikipedia.org/wiki/Deimos_(moon)

Both Phobos and Deimos have very low gravity that would allow rather huge, ungainly cargo transfers between Earth and the Mars system. Just dock with the moonlets...then build a colony or transfer to the Martian surface...or whatever.

 

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4 hours ago, DogOnPorch said:

can forget your Martian space elevator, btw. 

;)

Nah. It's got a 1 degree orbital inclination. That keeps it plenty far away from a space elevator most of the time. And, unlike the millions of pieces of space debris in Earth orbit, Phobos is easy to track. When it crosses the path of the space elevator, you just send a mechanical wave through the tether from the base station which deflects the tether away from the location of Phobos' passage. 

As for Deimos, it sounds like a pretty good space station at the end of the space elevator tether to me. You just have to speed up its orbit from 30.3 hours to 24.6 hours so that its Areosynchronous. That or put the space elevator base station on a rail track that follows the Martian equator and moves to keep in synch with Deimos. 

Edited by Bonam
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A space elevator on Mars would certainly be a good point, try it there before we can try it here.  I agree the elevator may actually be more than a century off.  Then again, some people said the same thing about space travel or a lunar landing, that it was decades away from 1961, and yet we did it within eight years.  Not saying it's going to be that fast, but once atomic power (or weapons) were considered impossible.  It would be the ultimate engineering achievement of course.

How many of those land-able rocket boosters have landed successfully? What's the batting average so far?

I'm pretty impressed with the knowledge of space travel floating around here.  I'm glad I put this thread out.  Much better than arguing about the bible or US foreign policy at this point lol.

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8 hours ago, Bonam said:

Nah. It's got a 1 degree orbital inclination. That keeps it plenty far away from a space elevator most of the time. And, unlike the millions of pieces of space debris in Earth orbit, Phobos is easy to track. When it crosses the path of the space elevator, you just send a mechanical wave through the tether from the base station which deflects the tether away from the location of Phobos' passage. 

As for Deimos, it sounds like a pretty good space station at the end of the space elevator tether to me. You just have to speed up its orbit from 30.3 hours to 24.6 hours so that its Areosynchronous. That or put the space elevator base station on a rail track that follows the Martian equator and moves to keep in synch with Deimos. 

 

Speeding-up Deimos's orbit? I doubt we have the ability to break an entire moon into a lower orbit anytime soon. As for deflecting the tether...also pie-in-the-sky. Good science fiction...plus...saying you could, you'd be doing it up to 3 times a day to dodge speeding Phobos. Something's going to break...

Phobos is pretty big for a rock...a 30km potato. The gravity, while low, isn't insignificant. Perturbation of anything like a tether near it would be likely leading to who knows what? Tether coiling? Pinwheeling? Better run some simulations....

This is also an issue with any space elevator concept. The tendency is towards dragging and coiling, naturally. Any variation away from 'the perfect orbital velocity' at 0.000 eccentricity is going to lead to problems quickly. Very quickly. Thus some means to keep the line perfectly taut (at zero eccentricity)  might be needed besides just relying on pure physics.

Mars...you need less than 4km a second to reach low orbit...pretty easy compared to Earth...elevators aside.

Edited by DogOnPorch
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25 minutes ago, JamesHackerMP said:

How much would a tiny little Martian colony cost to maintain? or even to land a man on Mars in the first place?

 

Quite expensive and due to the approximate 2 year difference in oppositions, it would need to be fairly self-sufficient. Good launch windows to Mars are comparatively rare. So any emergencies would have to solved there...not here.

It would be actually cheaper to build a colony first on Phobos due to the low gravity. Once established there, move to the surface at our leisure. 

Edited by DogOnPorch
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1 minute ago, DogOnPorch said:

 

Quite expensive and due to the approximate 2 year difference in oppositions, it would need to be fairly self-sufficient. Good launch windows to Mars are comparatively rare. So any emergencies would have to solved there...not here.

It would be actually cheaper to build a colony first on Phobos due to the low gravity. Once established there, move to the surface at out leisure. 

Yeah, but if you sneeze it'll literally throw you out into Martian orbit, or beyond, right?

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Just now, JamesHackerMP said:

Yeah, but if you sneeze it'll literally throw you out into Martian orbit, or beyond, right?

 

Not quite that low: 0.0057 m/s²  (Mars = 3.711 m/s² and Earth = 9.8 m/s²)

But it's low enough that one could gently land some VERY large craft w/o much effort. Pull up to Phobos and dock, practically.

Deimos has low enough gravity that you could toss a baseball and reach escape velocity, mind you. 0.003 m/s².

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Apparently, Red China's new heavy lift Long March 5 blew-up during yesterday's launch. Footage is unavailable...

The Long March series hasn't been the most reliable...or safe. Yet the Reds have rated this critter for manned launches.

Good luck, future crews...

 

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Here's the footage that does exist....right-up to just before strap-on booster separation. So my guess would be the missing KABOOM was a result of said separation.

https://www.youtube.com/watch?v=NahRe9rqo1I

Red China...still keeps you guessing...

(Note: the Long March uses hypergolic fuel...two chemicals mix and spontaneously ignite...a very dangerous type of rocket fuel...but they can be fueled and kept at room temperature. However, the fuel is so corrosive, that the rocket MUST launch within a short period of time before the fuel damages the engine!)

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55 minutes ago, JamesHackerMP said:

Is there any way to clean up the s**** that's floating in Earth orbit???

 

Most of the sh!t is in LEO and will reenter eventually.

It's the geostationary orbit that needs the real cleaning-up as that stuff is up there forever unless acted upon. Most dead satellites are still worth millions, so salvage seems practical.

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Well if they're going to build a space elevator within the next two hundred years, they'd better get cracking.  I'm still in favor of one of those.

Nonetheless, I think private industry will help the second space race happen.  During the Cold War it was awesome how we were beating the russians. Surely the successful moon landings by the United States helped contribute to the downfall of the USSR.  But once more fiscally conservative politicians were able to throw the dollar signs in front of everyone's faces, the optimism toward space travel faded.  The shuttle was amazingly expensive.

What we need is something that can take off horizontally, from a regular runway, like the SpaceShipOne/White Knight vehicles.  You could put "stuff" in orbit via more traditional launch vehicles, but send the people up in space planes; some sort of reusable vehicle that would take people up who might be there for a short trip, and not for the long-term rigors of living in zero G.  Even to go on the space shuttle as a "passenger" (like Sen. Glenn did some years ago) required special training, some of which the former astronaut would have been familiar with.

In 2001 A Space Odyssey, the Chairman of the NCA (like NASA Administrator) travels to the Moon via a special space plane that is even painted "Pan American" on the side.  (In the sequel made in 1980s, there was a fake commercial to fly Pan am "Where the sky is no longer the limit"). Take into account also that Dr Floyd was wearing a business suit on his trip rather than any special garments conducive to space travel.

I guess it wouldn't be that simple would it?

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Reusable boosters are a far cheaper way to go. We know this from experience, now...

Getting your little pinkish bod to 7.5 km a second is going to involve G-forces no matter what beast you ride into orbit. How many is the key. If you can keep it to about 3-Gs like in the STS program, even old Senators can make the trip. Riding one of those Chinese Long Marches at about 6-7 Gs while experiencing extreme POGO oscillations is enough to make even those Test Pilot types yell "ENOUGH!!!!" 

https://en.wikipedia.org/wiki/Pogo_oscillation

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21 hours ago, bcsapper said:

Space Pac-Man!

Not far off of some ideas...

But, keep in mind that some of those dead geostationary telecommunication satellites are the size of a bus. 

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A further note on POGO oscillations...

The type of fuel being burned as well as the design of the fuel tanks/turbo pumps greatly affects oscillations. Anything involving Aerozine 50 or Hydrazine  seems to invite these incapacitating vibrations. On the old Gemini-Titan II rocket from the 1960s (Aerozine 50), the POGO was only dampened somewhat by baffles in the fuel tanks, forcing NASA to make all the relevant gauges/controls HUGE so as to be readable while the crew's eyeballs vibrated at whatever frequency the rocket was at...

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