Polesitter 3 - Angie letter pt. 2: Something new in the south in The Amalgamated Aggromulator

  • Aug. 11, 2015, 9:15 p.m.
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The email continues.



So, with this winter of discontent about the future of space (or about the torpidity of its approach) in the background . . . what am I thinking that Australia should do in space, anyway?

Something for Australia’s own benefit.

Example: Japan is thinking about building space solar power stations for itself! Solar panels in space, and then they beam the electricity down in microwave frequencies to receiving sites. That’s practical. That’s for security and prosperity.
(It’s also how we can really learn how to do things better in space - because we have to, working on a real project important for other than just intrinsic reasons. That’s when we actually do figure out how to string a cable in free fall quickly, instead of it being a Grand Challenge as it takes a couple of days. But I digress.)

Well, I mentioned that Australia must presently hope, and ask, to get its satellite info from its partner nations, who tend to have their own agendas and schedules and their own budget problems.
And other countries’ satellites may not be properly placed to get the info Australia needs. Australia is a long way from other areas of interest.

I was thinking grumpily that Australia should make its own satellite. Satellites.
And, of course, at the moment Australia would have to pay for the launch through its partners’ facilities - borrowing space on its partners’ rockets. And I was thinking no, dammit. Australia could pay for someone else to build the satellite, yes, and Australia could pay for someone else to launch it, yes, but god damn it, god damn it . . .

By the way Woomera’s just fine for launching polar sun-synchronous satellites, launched slightly southeast and southwest. Which is most of what Australia needs. (To launch geosynchronous - east-west, meaning eastward to get help from the spinning planet - Woomera is about the same distance from the equator as Cape Canaveral, but a second site at Darwin would be better, yes; fewer pesky towns to the east to drop stages on . . .)

Australia should do it its own way. Its own satellite or satellites, its own way, its own reasons. And could.
(For one thing, to show itself that it could and of course it could.)

. . . And it occurred to me that there was a way that Australia could REALLY do it its own way. And Show The World. And show certain parts of it Up.

(Note: This is where I lapse into madness. Or may do. I am proposing a reach, albeit a reach that I think Australia could make.)

I started to wonder if Australia could make a solar sail.

And I really can’t answer that, or how much R&D it would take. The sail material is one thing, and is challenging (especially to make it as well as possible) but it’s basically simple, and to improve it as needed wouldn’t be harder for Australia than for anyone else . . . I’ll assume that it’s well within Australian industry project range.
Up a level, then, to the sheer cleverness of designing a good working solar sail spacecraft - I’ll assume you’ve got smart young people, who are already into space; in fact I don’t need to assume, I even know where to find a lot of them in Australian academia, I’ve been researching. I’ll assume that Australia could then build anything that your smart people could dream up.
The rocket to launch one kind of satellite or to launch something else like this thing I’m thinking of . . . what, the rocket? That I’m sure Australia could pull off.

There is a constraint that is a pain in the arse: The size of a solar sail you (or anyone) can put up is limited by how thin the sail material can be, which affects how much of that material folded (along with the rest of the craft) you can fit into a launch payload of a rocket. And then of course you’re stuck with having to have the sail folded (and needing the super-thin material to survive folding), and how to get it unfolded once it’s up there.
This is a limit - until or unless someone figures out how to spin a sail up there, not down here - or how to unfold and connect several pieces of material together in space after they’ve been launched independently.
I don’t know if there’s a deal-killer in here. There could be. This idea is not a snap “out of the box” - this will be a problem for the bright Australian space kids to get together and sweat over. For the moment I will assume it’s not a deal-killer. It would be lovely if not. I’ll assume that Australia is perfectly capable, especially once the effort got rolling, of making satellites, making rockets to launch them, flying those rockets . . . and designing and making a special solar sail.

But why?? What does this solar sail business have to do with anything?

What does this have to do with Australia having and launching its own satellites to look at Australia for its own practical reasons?

Potentially everything. One (or more - if it works, God, yes, more) of those satellites could be very, very special.
Because it wouldn’t actually be a satellite at all.

You see:
All geostationary satellites have to be right smack above the equator. That’s simple. Because the Earth rotates, and orbiting objects fall around the Earth’s center of mass. They can’t be made to fall around one end of the Earth, say at a particular latitude, and ignore the rest of the planet. So, to stay above a fixed point on the Earth’s surface, geostationary satellites are all equatorial, and at just the right (quite high) altitude for the speed of a circular orbit to match Earth’s rotation.
All non-geostationary/non-geosynchronous satellites fall around the Earth’s center of mass too, just in all different directions and at all different altitudes. (Satellites that look at Australia, at least that get a look directly at southern and central Australia, are usually satellites falling along polar orbits, north-south or south-north.)
But.
Solar sails present the possibility of making something else - a body which isn’t going round the Earth, that isn’t in orbit around the Earth and therefore isn’t a satellite, but that simply stays near the Earth as the Earth moves along. Holding its position by using a sail to catch light pressure from the sun and to balance that pressure against the anchoring gravity.
This thing has been named a “statite.”
And one of the major uses of a statite is to approximate (never perfectly) a “geostationary satellite” which is located, not at the equator, but at either the north or south pole. It would just always stay by the pole.

As I say, never approximate perfectly. The statite must always be somewhat toward the night side of the planet, to catch the sunlight. How close to the pole it can manage to be depends on how advanced the solar sail design is - more deflection away from the pole for less advanced sails, less for more advanced sails.
(Close to the pole, a statite could be in constant line of sight of the high latitudes, day or night. Further from the pole could also have potential advantages.)
A statite must also be a lot (a LOT) further away from the Earth than geostationary satellites are, so that Earth’s gravity and the sunlight can balance each other. Again, the more advanced the solar sail design, the closer to the Earth the statite can be.

This puts an extra level of design challenges on Australia - to make the solar sail as advanced/clever as possible, and to make the cameras, sensors, etc. to be carried by the statite more powerful in order to compensate for its distance.
But there would be something new in the Southern Hemisphere sky, for Australia’s own practical purposes.

. . . And I’m now tired. It’s another late night (pish, it’s early morning). But that’s the daydream.

How is that for Australia doing for itself? - and showing the lazy, groggy giants that space is not just a matter of flying redundant toy prototypes for the nerd enthusiasts, and that the potential of space needs - and rewards - thought and daring?

Here’s Robert Forward’s patent for the statite use of solar sails, where he lays the whole thing out. Do look. There are more cool wonders in there than I have the brain to translate into this email, and it’ll fill in the details.
(A “solar photon thruster”, by the way, is an advanced solar sail design where the sail is always facing the sun full on, for maximum light incidence - and the sail is parabolic, so that it focuses the reflected light on a smaller mirror-sail that is then pointed in whatever direction thrust is wanted. I can’t remember if Forward defined it in there, though he refers to them.)

And - regardless of statites - yes. Australia should have its own space program, and launch its own satellites with its own rockets for its own reasons.

And can.

I don’t know if I’ve sleepily written well enough to succeed in giving you a pang, but I hope I have.
This is a dream thing, a right-brain thing.
I still have two countries in my heart, a little. I’m kind of writing to one in this email. The other needs water flicked in its face from time to time, to nudge it to wake up to things, and I’d like to think the first one could help. :-)

Anyway - sleep now.

Alex



That was the grand vision.

How does it look since I wrote it, with the enthusiasm-scales off my eyes? I can’t say. :-) I don’t know enough. I would have to actually be in the field. And there is no objectivity whatsoever in any of this - and I don’t really want any.
Statites will not be an easy nut to crack. My understanding of the shape of the problem has improved since I wrote it. I should include the graph from Forward’s patent that defines the target requirements for various distances from Earth and proximities to the pole. Here it is; I’ll put it at the end.
It is possible that this is only a fun fancy. But I have no need to conclude that it is. (Nor do I have the background to close the door on it.) That should be up to the very bright and eager people who go through the university space courses in Australia with no national space program in sight, and still do it, and up to the materials scientists they’d corral.
Will the requirements for a polesitter be cracked at some point?
I think: Yes, when somebody tries, unless nobody tries, and not until someone tries.
Is Australia less able to manage it than the other candidates that come to mind?
With those bright, determined young scientists and the fruits of Broken Hill? I would not like to say so. It doesn’t take a large population. It takes enough of a nation, in which there are a few people trying.
Should Australia take a crack at it?
Someone should. And Australia?
A steady, continuous gaze on southern Australia, passes be damned? Or a stable, slow-passing gaze on the whole of Australia at night?
(And Argentina paying Australia for data?)
And a world marvel - “the Aussie way”?

Yes. I’d love to see Australia do this.
And, by the looks of things, no, NASA is not going to be stealing your thunder when you’re just getting started.

And in the meantime - or regardless - Australia should build its rockets and launch any conventional survey satellites it needs, of exactly the types it needs, to be placed in any orbits it needs.

And also - even without getting to full statites - I know that Australia could fit out the best solar sail spacecraft to date. Why not?

And a certain town should grow and live again.
There should be Anzac parades again along Dewrang Avenue.
Schoolchildren should stand in groups up on the oval to watch an infinitely fine needle of cloud rise on the horizon.

(And . . . whatever very highly suspicious-seeming administrative decision or re-balancing or relaxed attitude allowed a mass absconding with houses from an Australian Department of Defense Prohibited Area . . . I am thinking that there ought to be a new, reversed flow. Roxby Downs should be raided. Woomera 3: The Revenge. )

:-)

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Last updated August 12, 2015


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