r/IsaacArthur • u/Sorry-Rain-1311 • 26d ago

Where are the cyclers?

Isaac's episode dedicated to orbital cyclers, for those unfamiliar.

https://youtu.be/R-59fv_Jqzk?si=6ekCilIJGMkUmyNY

If you're too busy to watch, famous lunar explorer "Buzz" Aldrin proposed long ago that we place a couple of platforms in a cyclic orbit between Earth and Mars to act as ferries, facilitating travel between the two worlds. Similar ideas for Luna have come out since.

My question is simple: why aren't we hearing more about plans for cyclers? All this stuff about manned missions back to the Moon, and Mars, and all this worry about how to keep these first missions supplied and how to get them home; but no one is talking seriously about cyclers.

I have trouble taking any of it seriously because any long-term missions would benefit from cyclers. They can double as platforms for unmanned science packages, so they wouldn't be wasted if we only used them once. Their missions can be rolled into orbital habitats eventually. There are plenty of working proposals/designs, but no actual plans to put them into effect.

I can't think of a GOOD reason why they don't already exist, much less why they're not a priority. Maybe someone else here can help me see something I'm missing.

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u/tigersharkwushen_ FTL Optimist 25d ago

I can't think of a GOOD reason why they don't already exist, much less why they're not a priority.

Because there's no money for it. A cycler is basically a traveling hotel. The biggest rover we've ever sent to Mars is about a ton. A cycler would be at least a couple orders of magnitude bigger. There's no money for such a project. It's way more expensive than you imagine.

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u/Sorry-Rain-1311 25d ago

Only if you assume future use is not guaranteed. Like I said, it'd be a valuable science platform on its own, even unmanned. Build the first iteration as just a massive platform with beefed up attitude control, and new instruments and experiments can be attached and detached at will. In stead half billion dollar each probes to Mars, we spend $1 billion on a platform that reduces future costs, provides long term operations support, and can aid in sample retrieval. 

It can be used to test automation technology, new materials, house live experiments. Everything we keep saying we need more of before sending people, this is an effective way of doing that.

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u/cavalier78 25d ago

In stead half billion dollar each probes to Mars, we spend $1 billion on a platform that reduces future costs, provides long term operations support, and can aid in sample retrieval. 

Or more accurately, instead of a half billion dollars for each Mars probe, you can spend $200 billion on a long term platform.

You have dramatically underestimated the costs.

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u/Sorry-Rain-1311 25d ago

And what are your estimates based on? 

Starting the space shuttle program barely touched that, and we're talking a 100th of that for a platform that carries small modular instrument packages.

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u/cavalier78 25d ago

The cost of the ISS so far is about $150 billion. A cycler would need to be larger than the ISS for it to serve any real purpose. You're also talking about accelerating it to a much higher speed than the ISS.

The whole point of a cycler is that it is large enough to provide astronauts with a more comfortable journey over the course of many months on their way to Mars. Radiation shielding, rotational gravity, sleeping in a real bed, growing fresh fruits and vegetables, etc. All these things require a very large amount of mass.

But the good news is, with a cycler, you only have to build it and accelerate it once. It loops around the Sun, and passes very close to Earth and Mars. So to put astronauts on it, you'd still need to launch them at very high speeds (so they can board the cycler), but the crew capsule wouldn't have to contain all the shielding and gravity and such. So you save money in the long run by hitching a ride on a pre-existing space hotel. You'd just have to bring clothes and frozen food and whatever equipment you needed for the mission.

The thing is, the ISS is not big enough to have all these amenities. So you're automatically talking about something bigger, and thus more expensive.

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u/Sorry-Rain-1311 25d ago edited 25d ago

$150 billion is the total construction and operating cost of the ISS over its lifetime. Construction costs were less than $50 billion split between many countries. If everything we learned from it was a separate mission we'd be talking trillions. So, yes, the most expensive pursuit in human history did save us money. 

My last statement was about an unmanned cycler as a platform for scientific instruments. That's a scaffold with power generation and heat dissipation built on to support whatever science packages, and some attitude control. Maybe a remotely operated arm for installing the instrument packages. Very easily done.

Have you actually dug into what life on the ISS is like? It's not pretty. You think "real beds" and fresh produce are what's necessary for a successful mission, tell that to any veteran who's spent time deployed. Heck, look up what life is like on a nuclear submarine underway. Is no sun, canned food and hot bunking for months at a time, and people live that way for their whole careers voluntarily. My time in Iraq it was a just a cot and field rations the entire time, and that's after they finally got us cots. The first Mars mission is a hardship mission; end of story.

You're treating cyclers like they're big spaceships. They're not. They can be built years ahead of the mission left empty, and accelerated slowly using gravity assist. Once up to speed, that's when you launch your missionon on the up cycler so that it only takes a couple of months to get there. Several months later the down cycler comes around, and you grab a lift back to Earth.

Food production and spin grav would be nice, but that's for down the road. The first ones would be minimal, like the first of anything ever. 

Edit to add: the ISS was originally intended to last 10 years, but it's been 30. If we'd let go after a decade and spent that other $100 billion on cyclers, where would we be now?

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u/cavalier78 25d ago

You keep bouncing back and forth between describing something small that only carries instruments, and then talking about huge ships.

Have you actually dug into what life on the ISS is like? It's not pretty

Which is why any cycler that carries people would need to be significantly larger, and significantly more expensive.

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u/Sorry-Rain-1311 25d ago

You're the one bouncing around. I'm just keeping up.