Yeah, it instantly makes sense if you calculate the force at the Lagrange point and notice the vector points back at the exact L point when you're in the vicinity - and then you go, hmmm, looks like it might be possible to orbit that thing.
Will L2 congestion become a problem once JWST and a few more missions join this craft? Will we have to manage that orbit like we do with geostationary?
>A full n-body dynamical system such as the Solar System does not contain these periodic orbits, but does contain quasi-periodic (i.e. bounded but not precisely repeating) orbits following Lissajous-curve trajectories. These quasi-periodic Lissajous orbits are what most of Lagrangian-point space missions have used until now. Although they are not perfectly stable, a modest effort of station keeping keeps a spacecraft in a desired Lissajous orbit for a long time.
https://en.wikipedia.org/wiki/Halo_orbit
"Halo orbits can be thought of as resulting from an interaction between the gravitational pull of the two planetary bodies and the Coriolis and centrifugal accelerations on a spacecraft."
With air being so dense and power-dissipating, it might be more economical to do a sub-orbital jump than to push through the atmosphere at 7M. For short-range military applications, iirc, hypersonic rockets exist.
You've gotta consider how much things change as you get higher into the atmosphere. The obvious thing is that atmospheric oxygen begins to become insufficient to operate engines as you go higher up, so you need engines that use a different oxidizer than atmospheric oxygen which is extremely complex. And even the efficiency and characteristic of engine exhaust changes radically depending on atmospheric density and the characteristics of its exhaust. In other words an engine that works great at sea level might work awfully when you start to get to a fraction of the same pressure.
There's an immense amount of flexibility in being able to travel hypersonic. The SR-71 Blackbird is an amazing example of the potential. First flown back in 1964 (!!) it was capable of hitting around mach 3, some 2200 miles per hour. That's 6 hours to get from one side of the Earth to the other. It's really quite remarkable how much our overall transportation technology seems to have stagnated since the 60s. I'd like to imagine everything is just classified but everything from the SLS to the F-35 to even things like the Zumwalt just seems to indicate that we've simply technology regressed. Kind of disconcerting to imagine the reasons for that.
All current military hypersonic (Mach 5+) weapons are ballistic missiles. No one has demonstrated sustained hypersonic flight through the atmosphere but that's probably coming in a few years.
Ironically, these were mostly the same thing during the space race. I watched a USAF training video on re-entry mechanics[0] a while back that really drives this home in an almost dizzying context switch. It goes from the mechanics of delivering a thermonuclear payload in one sentence, to returning humans to earth in the next.
There is no way a space race like the one during the Cold War can appear again. Nonetheless the term space race is often used by the media just because it sounds more dramatic.
we used to invest $3 into infrastructure and science for every $1 in entitlements spending. Now we spend $5 in entitlements for every $1 in infrastructure/science
And people wonder why the US is falling apart and technological advances have slowed down.
We're living hand to mouth instead of investing in the future. The sad thing is that many of our problems could be solved permanently via technology rather than government.
Instead of creating the automobile people are trying to make horses faster
It feels like we slowed down in the important areas. Software? Web Apps? We're doing great. Anything space related? Eh. In theory we get to claim SpaceX so I guess that counts but most people couldnt tell you what NASA's been up to recently...
I wouldn't say "vague". He cited the differential in dollar amounts and drew a conclusion from the data presented. That sounds specific to me. I think you may have overreacted to his point. You should have debated the merits and demerits of welfare spending versus R&D investment. Instead you accused him of something he never advocated for.
I would expect some nationalistic fervor that would help fund a space race would come from US conservatives.
But in the US the "conservative" side of politics seems more interested in short term tax cuts for corporations, dismantling government, and hating on immigrants, and other Americans...
Accepting your blatant mischaracterization of conservative US politics as true for a moment, I think given the choice between "othering" folks in the US or a country on the other side of the world that most people know nothing about, politicians of any stripe would prefer the latter.
"I think given the choice between "othering" folks in the US or a country on the other side of the world that most people know nothing about, politicians of any stripe would prefer the latter."
Show me reigning US conservatives who aren't espousing those ideals cited. Go on, I'll wait. Even the libertarian puritans like rand paul have fallen in line with the socially and economically regressive republican platform of today.
The only ones willing to stand up to the hypocrisy of Trump and actually represent conservatism have been sidelined consistently.
In space flight some of the most advanced technology even to this day was developed in the 60's and 70's. Things like NERVA[1], the NK-33[2], and the Saturn V[3], were developed back then and are still more efficient or bigger then similar technology we have today. The 60's and 70's were the golden age of spaceflight.
If you keep breaking the guidelines we'll ban the account.
> Please don't impute astroturfing or shillage. That degrades discussion and is usually mistaken. If you're worried about it, email us and we'll look at the data.
Ok I'll refrain myself next time. I'm hoping you monitor suspicious activities and accounts on here, including where the trails ends up, because I assure you weird things are happening. There's an unnatural tendency to favor a view as of lately.
Huh, interesting. I'm left wondering whether China has a Planetary Protection Officer, though of course the Moon is barren so it doesn't really matter…
It isn't just barren. It's sterilized of any Earth life that may have happened along every month, which gets up to 250 degrees F (~120 C), and even if something survives that, there's never a window of time in which something like livable conditions obtain, because once out of the sterilizing sunlight the temperature immediately heads for a decent approximation of the average temperature of the cosmos. (Doesn't seem to quite get there, but it's cold enough that you could pour liquid nitrogen on to the ground and it would stay liquid if you held it at 1atm pressure. Dunno about vacuum.) So between the extreme thermal cycling and hard radiation, even Earth's best aren't going to get a foothold up there.
This is in contrast to places with a non-trivial atmosphere or standing liquids, which may moderate the environment enough that something could conceivably live. Something could conceivably live on Mars, something that isn't even necessarily that far from some things that live on Earth. Nothing will live on the Moon. You can fling as many gallons of the scummiest pond water you can find from any pond water on Earth on the moon, and you're not going to "contaminate" it with life.
We really, really need more data on the responses of living creates to 1/8g. We've got all the 1g data. We've got a considerable amount of 0g data from ISS experiments. But we just don't know how living creatures respond to lunar or martian gravity. And knowing that will be very important for future colonization efforts.
Spin can indeed create (effective) gravity, but it differs due to the coriolis effect. We'd have two options: We can build a really big satellite, so as to minimize that effect -- or we could assume plants aren't sensitive to it, and hope for the best.
Needless to say, most scientists aren't fans of the second option.
Incidentally, long-term it would be possible to achieve 1g on the moon by way of a similarly huge centrifuge.
I can't grasp the centrifuge option, won't there still be two forces?
It'll be more like those carnival rides than artificial gravity. A dropped ball won't fall straight "down".
Yes, exactly what I meant. It seems a lot easier to get an experiment into orbit than onto the moon. If you connect two halves of the satellite with a long tether, you could reduce the coriolis effects, if that's really an issue.
The relay satellite included two micro-satellites for the moon, only one of them survived: http://www.planetary.org/blogs/guest-blogs/2018/20180615-que...