Monday, April 26, 2021

Some ideas for space missions

I am a big supporter of space exploration.  And as a scifi writer, I spend a lot of time thinking about ways to explore the solar system and how they could be worked into stories.  Along the way I’ve come up with some ideas for space missions which I think would be cool or would help in making humanity a spacefaring civilization.  Over a year ago I wrote up Some ideas for small lunar landers, and I guess you could say this is an extension of that, although these are big missions that go everywhere else but the moon.  I’m not an engineer, so these are more back of an envelope ideas, but if you are a space engineer and you’re looking for something to do, maybe one of these will spark something.

Deep space antenna

We have dozens of spacecraft across the solar system, and they all need to communicate with Earth.  Most do so through the Deep Space Network, which is a series of radio telescopes placed across the world.  So far, so good, but as we start sending out more and more probes, there could easily be a bottleneck in communications.  My idea is to put a big ass antenna out in space.  Part of the idea is that if we can make the antenna really big – say 100 meters in diameter – it would make it easier to get the weak signals from extremely distant spacecraft, such as New Horizons. 

Where would you put such an antenna?  I’m thinking maybe twice geostationary orbit, so the antenna would take two days to orbit the Earth.  The reason you’d want to put it out so far, is that in lower Earth orbit a 100 meter antenna would be damaged by debris and the faintest traces of atmosphere would work to deorbit the craft.  Also, it would probably be rather bright.  Geostationary orbit is full of communication satellites, and just outside of geostationary orbit is a graveyard orbit of dead communication satellites, so I’m thinking that at twice geostationary orbit there would be plenty of open space with little interference.

How would you get something that big out there?  I’m thinking you build and launch it in three parts.  The first part would be the main antenna which would be as big as can be origamied into a rocket fairing.  The second part would have the solar panels, all the electronic stuff, and the antennas to talk to the ground.  The final part would be the engine to get it into the proper orbit, and would handle all the station keeping aspects of the mission.  The best part of this idea, is that when the fuel starts running low, you could launch a new station keeping module to replace the old one, so that this antenna would stay functional for decades. 

Could you fold up a 100 meter antenna to fit on a rocket?  Those might already exist, I just don’t have the security clearance to know.  But if you could only fit, say, an 80 meter antenna on a rocket, that’s not bad.  But I had a crazy idea how to turn a measly 80 meter into a 100 meter.  What if on the outside of the second or third module there were preformed panels that a small robotic arm could attach to the folded up antenna to get it up to 100 meters?  A bit complicated, I admit, but is it really that far beyond our capability, especially if we get a really kick ass antenna out of it?  Of course, there’s no reason why we couldn’t build several of these antennas.  Well, other than getting the funding for them. 

Innersystem relays

As the author of The Moon Before Mars: Why returning to the moon makes more sense than rushing off to Mars, you can probably tell that I’m not one of these “We have to go to Mars, now!” people.  I fully support the scientific exploration of Mars – as well as all other solar system bodies – but my vision of human exploration of Mars is more akin to the International Space Station than Las Vegas.  And while I think we are probably twenty years away from humans on Mars, we do have several robots there.  That’s great, but sometimes in their orbits, Earth and Mars will end up on opposite sides of the Sun.  This means we can’t really send or receive signals for about two weeks.  During that time, our rovers just park and probably just take some photos and wait for us to be in contact again.

Just for safety reasons, I don’t think we should allow this for when humans eventually go to Mars.  My solution is to put a couple of relay satellites into orbit, probably between Venus and Earth.  So whenever the Sun blocks our view of Mars, they could just relay the messages and we wouldn’t have to worry if the crew is dead. 

But this only happens for two weeks every two years or so.  Building and launching a satellite just for that seems overkill.  So the main point of these satellites would be to observe the Sun.  And if you have two, three, or four of these spacecraft spread out, you can have a full view of the Sun. 

Multiple asteroid flybys

I see the real future of humanity in the Asteroid Belt.  As I’ve said before, “If we go to Mars, we get a planet.  If we go to the Asteroid Belt, we get the galaxy.” Because we can grind the asteroids up into their component elements, and build spacecraft that we can then send to other star systems.  Before we start colonizing the galaxy, we can use the resources from the Asteroid Belt for … just about anything.  We could mine the materials to build the factories that would build giant solar power stations, which could then be flown to Earth using asteroid manufactured fuel to supply all of our power needs.  For example.

But before we can start mining the asteroids, we need to learn as much about them as we can.  We’ve already flown-by or orbited a dozen or so asteroids, but I’d like to dramatically increase those numbers.  So this mission would be designed to take a looping orbit through the Asteroid Belt that would let it flyby … say at least ten asteroids.  Maybe even more.  But the interesting idea is that instead of just one, there would be three spacecraft.

I know that the Asteroid Belt isn’t like what you see in movies where there are thousands of rocks just rapidly flying around each other.  In reality, if you were standing on an asteroid and you were really, really, really, really lucky, you might see one other asteroid as a dim point of light at the very edge of vision.  I also know that orbital mechanics means flying between objects in space isn’t the same as flying between points on Earth, but I hope this idea could work.  Basically, you have three spacecraft that are mostly identical.  You launch the first one, wait a week or so, then launch the second, and wait maybe two weeks for the third.  The goal, is that the A craft flies by and gets detailed images of half the asteroid.  Then when B flies by, you adjust its path so it can image the other half.  And C fills in any gaps, or takes a closer look at something interesting the first two found.  As things stand now, if we flyby an asteroid and see some strange surface feature, it may be decades, or centuries, before another craft visits it to get a closer look.  With this setup, it may just be a few weeks.

The way you’d do this would be using ion engines, which don’t have much thrust because they go through their fuel so slowly, but since they go through their fuel so slowly you can run them for years.  Spacecraft A would have cameras and a bunch of other instruments as well as a small ion engine for course corrections.  Spacecraft B would have cameras and two-thirds of the instruments of A, to make room for a bigger fuel tank because it will need to make more course corrections than A.  And Spacecraft C would have cameras, the other one-third of instruments, and an even bigger fuel tank because it will need to make even more course corrections. 

A possibility is that if these craft are mostly identical, you could mass produce them and you could have four or five of these tri-spacecraft missions flying, sending back data on dozens and dozens of asteroids.  Or you might find another use for them.

Jovian moon explorer

Jupiter has about eighty satellites, that we know of.  Four of them are big and get almost all the news, while the rest are just small captured asteroids.  We do have a few grainy images of some of them, but the vast majority are just points of light in telescopes.  This mission would aim to flyby as many of them as possible, because every object in the solar system has a story but it is very unlikely there will ever be a mission to … Pandia. 

Jupiter is much farther from the Sun than the asteroids, so you couldn’t just send a set of the asteroid flyby craft to Jupiter.  You’d need to put on larger solar panels, for example.  But it’s possible the Jupiter craft could be a version of the asteroid craft, making the development a bit cheaper.  Saturn also has some eighty known satellites, but right now we don’t have the technology to power a spacecraft at Saturn with solar power, we only recently got that capability at Jupiter.

One thing both the asteroid and Jupiter missions would do is look for new asteroids and moons.  It’s likely there would be months, even years between flybys, and one idea is that the A and B crafts would have telescopes that could be used to search for small, dim objects in their vicinity.  If possible, there could be unplanned distant flybys of these newly discovered objects, which would be fantastic. 

The One Light Day Mission

Voyager 1 is the most distant human object.  Launched in 1977, it is now over 22 billion kilometers from Earth, meaning it takes over twenty hours for its radio signals to come back to us.  Meaning, even after flying for almost forty-four years, it’s not even one light day from us.  This mission is to get that far away from us in, say twenty years.  The way it does this is to launch the craft on one rocket, and then launch two more with booster engines.  The first one to attach, would be as big an ion engine as can fit in a rocket.  The second to attach would just be as big a conventional rocket as can fit.  This booster fires, gets it going as fast as it can in a few minutes, then detaches.  Then the ion engine fires for a decade, or more, slowly ramping up the speed.  Probably throw in a Jupiter flyby to pick up even more.  I know it would be a challenge, but what space mission hasn’t been?

The probe would have dust counters and magnetometers and other such instruments to study the interstellar medium, but it would also have a telescope.  Hopefully, the craft would be put on a course to flyby a known object in the Kuiper Belt, but the telescope would be used to look for objects too small and dim to be seen from Earth.  Also, once it got out to one light day, it would take a picture of the Sun.  In such a picture, would the Earth even be a pale, blue dot?

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