Cycler orbits are cool, but slightly over-constrained. You can pass close to Earth and Mars on a more interesting cadence if you're willing to burn a little fuel to adjust the cycler once in a while. The "perfect" cycle orbit ala Aldrin Cycler is just one special, theoretically-stable case.
So, Starship on a cycler-like orbit is _really much more powerful than discussed here_.
I once wrote a few articles about using custom-made cycler trajectories to ferry data back and forth.
* You don't have to accelerate data up to speed, just beam it to the "ferry" when it's close to Mars, and beam it to earth when you're close to Earth
* You can get _enormous_ amounts of data back this way, b/c you can use very high data rates when transmitter and receiver are close
* For example, you can map the entire surface of Mars in high resolution quite frequently, if you are willing to wait a bit to get that data back
* And you can still downlink data normally 364 days a year - with one day scheduled for a Petabit scale transfer to the data "ferry"
And if you scroll through, there's some examples of "ugly" cyclers, which have a more interesting cadence and require a little bit of fuel to maintain.
By batching ugly cyclers, you can get multiple flybies, and not just constrained to the synodic cycles of the two planets. For example there's a 1-2 /year flyby schedule.
Isn't the utility of the cycler that it can be a massive object with a lot of shielding for humans and permanently installed life support systems? Like a big space station for whole crews to live safely and comfortably while in transit.
You (incrementally) build up a large cycler in parts, each part accelerated to the orbit once.
Once the cycler is large, it seems infeasible to burn fuel to periodically adjust the orbit since it's massive. Unless propellant less stuff like light sails can be used over long periods.
Yes, it could be essentially a cruise ship for the journey, and starships are used just to ferry passengers and supplies to/from the cycler at each destination. With life support closure you might not even need much in supplies.
I wonder if it's possible (and sensible) to have a bunch of cyclers after each other, spaced eg a month apart. The distance between them would be much shorter than Earth -Mars and thus allow much faster data transfer.
With these cyclers as relays, there's always one close to Mars, another close to Earth.
We did look at that. In fact it's quite possible to have a "train" like this, but:
* Continuous relay is power-hungry, and the distances are still huge unless you have a _lot_ of relays on _very_ different heliocentric orbits. The scale of the inner solar system is _enormous_ compared to LEO. High power on lots of satellites means huge cost on a per-unit basis. LEO is 100km away vs 1/5 distance to Mars is still 80 million km or so. Transmission power for a given rate is d^2 (or d^3 in some cases for lasers). Enormous power requirements.
* On earth, you can "space out" an orbit so that you basically always have either another satellite on the same orbit, or a "nearby" orbit that has one coming up. Look at GPS tracks, for example. In inner solar system, everything orbits the _sun_, meaning nearby orbits might be nowhere near earth, and even a train on the same orbit is going to miss Earth 99.9% of the time by a million km or more.
* An interplanetary relay has been studied. Instead of cyclers which pass close, you basically put a "train" of spacecraft on a heliocentric orbit between earth and mars. Again, this was a lot of spacecraft required to get relays such that the cost paid off relative to just building bigger transmitters / listeners on earth or having more orbiters around Mars.
The sweet spot of cyclers is low thrust requirements, comparatively low system requirements (big burst of data once in a while with lots of charging between), which combined to make sats small enough to justify a dozen or so on a single launch of this purpose.
I _do_ think we'll have solar-system-starlink. Probably at Mars, definitely at Moon, and likely some lagrange point relays with a cycler or two funded by an eccentric billionare in 50 years.
EDIT: I misunderstood, below is old comment / reply
That is precisely the subject of the paper I linked. Except you can't confuse visit frequency with visit _latency_. We can have many visits per year but all the data coming down is usually over a year old. For Grand Science on a planetary scale this is ok. And for lower latency data requirements (of which there are not really many cases outside human impatience) you can use regular downlink but only .01% of the throughput.
But it gets even more interesting if the data "ferry" has enough compute to work while moving. You could run models on the ferry to answer questions, then every so often (when close to earth) download all the data to verify answers.
What we derive and optimize is the orbits to achieve such a "high frequency" cadence by formulating a set cover instance.
The sets are the visits for each cycler and we want to "cover" a given time span with "enough" visits.
And the cyclers themselves are a large parameter sweep conducted somewhat open loop.
Exactly. Have some sort of chain of cyclers that each cycle independently, launched/spaced (hehe) eg. a month apart. As they cycle, only one of them will be closest to Mars, that gets the uplink from Mars, then relay the data to the cycler behind it, that relays to the one behind etc etc until we reach the cycler that is closest to Earth, in mere minutes.
Can have laser links between them even maybe.
Bulk freight mostly doesn't need radiation shielding or life support services, so what would be the advantage to using a cycler station/shuttle for freight?.
You still have to boost the freight into the orbit to meet the cycler station/shuttle and deboost at the other end - why bother.
It's kind of like an updated version of the Colliers' Space Program. Huge infrastructure in orbit.[1]
"No budget is included for cargo to support passengers on Mars, as it is assumed by the time this is done there will be a well functioning city at the other end to support them."
That's likely to be a big problem. Most of the mass shipped will probably be cargo. Think in terms of an Antarctic base. Doesn't produce anything, totally reliant on external supply.
> Think in terms of an Antarctic base. Doesn't produce anything, totally reliant on external supply.
It doesn't have to, because shipping to an Antarctic base is both quicker and much cheaper than shipping to Mars. Making it completely self-sufficient would require a substantial investment that's not really needed considering we have ships that regularly do the journey.
OTOH, NASA could be interested in doing exactly that, as air and water is all they can have for ISRU (unless they hunt for penguins and seals), and there is already a bunch of extremely clever people on-site that would probably be glad to be able to grow plants during their winter stays. Fresh fruit must be something highly coveted in that place.
Not sure what this really gets you, since you still need to change your velocity in the exact same amount on both ends of the trip. The Cycler can get you there in four months vs a year... but you need to use just as much fuel on both ends of the trip as you would to make it in four months.
It seems the idea is that you could pack people in for the few-hour journey to the Cycler, and the departing journey once you get to Mars, and give them more space and shielding during the voyage. But that all requires that a large, spacious, well-shielded Cycler is already in place. This is all covered in the article, but just as an interesting aside rather than a massive impediment to the utility of such a piece of infrastructure.
All of this is such a distant problem, it seems way too soon to even speculate on. We're hundreds of years away from the logistics of transporting thousands of humans to Mars being a practical consideration. As such, the mere mention of Starship feels utterly anachronistic. Even if you think colonizing Mars is a good idea, wasting time thinking about problems for the year 2300 is not the best use of your time.
>> All of this is such a distant problem, it seems way too soon to even speculate on. We're hundreds of years away from the logistics of transporting thousands of humans to Mars being a practical consideration. As such, the mere mention of Starship feels utterly anachronistic.
This is not hundreds of years away, it is the goal of SpaceX. They are not just building Starship, they are building a factory with a target production rate of one ship per day. The goal is not to send a few ships to Mars, but an armada. With so many ships around, and a window to Mars about every 2 years it makes sense to start building infrastructure like this with them while they're waiting.
Yes, Elon is a bit... ambitious. And I question whether he is actually serious about it all. But if he is, this is happening over the next 50 years.
> They are not just building Starship, they are building a factory with a target production rate of one ship per day.
So SpaceX is going to build a Starship, which has to travel tens of millions of miles through the unforgiving frontier that is space, at one a day? Boeing manages to build a 737 in about nine days and those land on Earth every few hours of operation for maintenance and checkups.
>you still need to change your velocity in the exact same amount on both ends of the trip
You usually need to change your velocity more than that.
Cycler orbits are more constrained in their start/end dates, so there are fewer free parameters to "tune" for lower propellant consumption. Generally a cycler with a 4 month transit time will need slightly more delta-v vs. sending a ship on a regular old transfer orbit with an identical 4 month transit time.
This is because when designing a cycler orbit it's usually necessary to shift a few days ahead/behind the optimum dates for a 4 month transfer, in order to efficiently "stitch together" with the previous/next orbit cycle.
> We're hundreds of years away from the logistics of transporting thousands of humans to Mars being a practical consideration.
With decades of experience with the ISS and Starship's first orbital flight on the docket, why would this be hundreds of years away? Consider the technical progress we've made in launch vehicles in the last 15 years alone. Are there really any technical problems on the path to a mars cycler that could give us centuries worth of trouble? Or are you simply suggesting that the demand won't be there?
Way more distant if you consider how poor would be life on Mars.
Unless you think of it as a giant experiment to travel outside the Solar system, further down the road, when the Sun will eat up the entire solar system. In that case, though, you'll need a larger cycler with a much different shuttle for you to board/unboard it...
> Current space stations use their discarded cargo vessels to get rid of waste that cannot be recycled, leaving it to burn up in the Earth’s atmosphere. What a cycler could do is package it in some way that it could be fixed to the outside of the station.
This is quite funny to think about. Seeing a trash laden ship blasting past would be quite the sight.
So if a starship needs to rendezvous with the cycler to transfer passengers/cargo, it could simply be added to the cycler, at least during an initial cycler buildup phase. Linking starships shoulder to shoulder in a ring with noses pointing into the center and engines facing outward might be useful. Spin it up to give whatever gravity is desired in the same direction as an upright starship on earth. Linking corridors extruded from the starships could be used to convert the collection of ships into one station. A special purpose hub starship that provides an attachment framework and becomes the hub of the ring would allow firing its engine(s) to change the station velocity.
Exactly as described in Buzz Aldrin's book Encounter with Tiber. Very very good yarn about humanity's effort to walk between the stars using knowledge left behind by visitors, culminating with the first human to set foot on a non human world.
If you think that's bad, check out the (also terribly sourced) citation they linked for Apollo's exposure of 20 mSv through the Van Allen belts[0]:
"The actual amount of radiation received by the Apollo astronauts during their passage through the van Allen belts is difficult to determine but it is estimated to be about 2 rems (or 20 milli-Sieverts)."
A hyphen between prefix and unit? Capitalizing a unit that's named after a person? It's an absolute mess.
It seems almost nobody is aware of the (official/authoritative) SI brochure[1] anymore, or even its poor cousin, Wikipedia's Manual of Style for Units of Measurement[2].
Yes, "Watt" and "Newton" are surely the most common culprits.
When speaking of them as people, they are of course capitalized.
When speaking of them as units, they are not capitalized (1 watt). However the abbreviation is capitalized (1 W), and I think this is mainly what confuses people.
I don't want to get into a descriptivist vs prescriptivist debate, but it's worth noting that if "everybody" is doing something wrong, then maybe it is the specification that is wrong.
You have it reversed. The truism you're looking for is: "Just because something is popular, doesn't mean it's correct." Don't let Likes and Followers culture fool you.
If you want to make your own SI, feel free to use it however you want. If you use the SI, you MUST (RFC 2119) follow the official SI brochure, otherwise you're objectively wrong. That's what standards mean, and they exist for many good reasons.
It's not your fault. This flavor of philosophical deterioration happens when you tell an entire generation to follow their heart, everybody's a winner, and there's no wrong just "different." This mental trap is hard to escape, and worse it impedes self-improvement.
The spelling and capitalization rules of the SI system are not technical rules, they are a matter of language and do in fact vary. In German, for example, units are always capitalized in long form.
In the field of linguistics it very much IS the case that what is popular is correct. Beginning a sentence with a conjunction, or ending a sentence with a preposition is perfectly fine in English for example, despite what many outdated grammar texts would tell you.
I don’t know if units like watt or newton are more frequently capitalized or not. It is common though. In which case it would not be wrong to do so in a blog post. (For a submitted article you’d use whatever the editorial standard is though.)
It's made for another typographic environment, with restrictions that do not apply the same way today. And adds semantic noise to the text.
The Unicode people could make a different kind of space for use there, but I don't think anybody would adopt it. It looks like something that should be handled by a mechanism similar to ligatures.
I really wish people would stop using Medium. A problem I've been running into over the last few months is that an increasing number of potentially informative articles are hidden behind a Medium sign-in wall.
* Edit
As commenters mentioned this is on substack. My apologies.
I still stand by my original statement though. The sign-in walls are a problem.
Ironically when I go back to visit the substack link on the parent, there's no longer a sign in requirement.
Do you see the "Continue reading" grey text? It's clickable and lets you get past the sign-in wall. You don't have type your email, subscribe, or log in.
I usually close out of any sites that bring up such an attention-stealing popup out of principle, but I've found enough insightful content on Medium that I'm willing to ignore this dark pattern.
Your argument doesn't stand. I'm sure it's possible to paywall articles on those websites, but in every case I've seen the subscribe wall is dismissable with a single click. Annoying, yes, but more of a gate than a wall.
I hope getting humans to Mars can inspire more investment in space travel and exploration, or even another space race... but I'm not sure that it will happen. Putting 1000 people on a ship seems like a pipe-dream adjacent to full-self driving at this point.
At the moment all of this feels like a mistake... for the cost of a manned program we could be sending out dozens of probes and rovers, not only to Mars but to more interesting places like Jupiters moons, Io and Europa, the former being the most volcanically active body in the solar system, and the latter one of the most promising places to find liquid water.
I think sending a person across the ocean, under an atmosphere, protected from radiation, with gravity isn't "the exact same" thing as through space. Much less 1000. Pretending that it is...charitably...is silly.
Much harder to get the initial, small scale version of a cycler-based transit system established. But then, because you don't have an atmosphere or ocean or particularly noticeable gravity, scaling it up it probably much, much easier than doing so for ocean-going vessels and the like.
Maybe? My point is if you are going to do it, start with a mental model that fits the task, not one that both isn't remotely the same engineering challenge and ignores the actual hard problems.
Well, we're a good part of the way towards being able to move people from the earth's surface into orbit. Somewhere between, say, 20% and 80%. If that claim is true, then it seems reasonable to be thinking about what comes next, and building a small cycler seems like a potentially reasonable choice.
If we can indeed build a small cycler, then getting to a big one may be much easier than going from a small yacht to a transoceanic liner.
> If we can indeed build a small cycler, then getting to a big one may be much easier than going from a small yacht to a transoceanic liner.
It still falls apart a bit due to the rocket equation. [0] When you're in a safe harbor on earth, it's somewhat simple to increase the size of your boat, most of the rules stay the same.
But as you build bigger cyclers, one will either need bigger rockets or more rockets and then possibly assembly/docking in space, so it's definitely more complicated than making a larger displacement in the water.
That is true. My comment was more about the initial setup of a larger cycler. Larger cyclers will cost exponentially more rocket mass/fuel/complexity than a smaller cycler. But once in orbit, yes, the design reduces overall fuel costs.
The mass a rocket can lift into space is inversely proportional to the mass of the propellant. To increase the payload (a larger cycler like the previous poster mentioned), you need to increase the initial total mass of the rocket, which includes the mass of the propellant.
So it's not linear, it's exponential, the "tyranny" of the rocket equation.
Or are you talking about a completely different equation?
This one, which is the only one I know of to get this moniker, is about mass fraction, not absolute mass. You can perfectly compensate for making m_f bigger by making m_0 bigger by exactly the same ratio, hence for fixed Δv, m_0 increases linearly with m_f.
Two rockets joined horizontally has twice the mass of one rocket alone, and accelerates twice as much payload to the same relative velocity as a single rocket.
Two rockets joined end-to-end, with the second rocket being the payload for the first, makes the ultimate payload of the second stage go faster than if it had only been propelled by the second stage with no boost from the first, but significantly less than twice as much faster.
You can also see this example by asking the inverse: if it was exponential with regards to absolute payload rather than the payload as a mass fraction, that would mean that dividing any given payload into two or more parts, launching them separately to the same ultimate velocity, and having them join together in space, would save fuel — it doesn't, QED.
(There are other reasons to build in space, like "our rockets aren't big enough and nobody wants us to build bigger ones", but that's a political equation, not rocket science).
Eventually yes, but it seems we're putting the cart before the horse.
I really hope it goes well and we end up accelerating things with another space race, this is the best outcome and maybe this is why we're shooting for manned Mars missions... but it's risky. A crew of dead astronauts on Mars could have the opposite effect. Imagine if Nixon really had to deliver that failure message about the moon landing, space exploration could be even worse off than it is now.
People and governments make all kinds of mistakes, and when comparing manned to unmanned space programs and their relative costs, it's worth examining what the overall societal expenditures look like.
For example, the cost of maintaining the USA's nuclear arsenal is very comparable on a yearly basis to the entire NASA budget (~25-30 billion). However this pales in comparison to the complete amortized cost of the US adventure in Iraq from 2003-2008 or so, which is on the order of $2.5 trillion (large error bars there), or about $500 billion per year.
Conclusion: we certainly have the civilizational resources to increase both unmanned and manned space programs by at least 15-fold each if we'd just stop wasting money on stupid wars. Note that's just USA expenditures, as well.
So, Starship on a cycler-like orbit is _really much more powerful than discussed here_.
I once wrote a few articles about using custom-made cycler trajectories to ferry data back and forth.
* You don't have to accelerate data up to speed, just beam it to the "ferry" when it's close to Mars, and beam it to earth when you're close to Earth
* You can get _enormous_ amounts of data back this way, b/c you can use very high data rates when transmitter and receiver are close
* For example, you can map the entire surface of Mars in high resolution quite frequently, if you are willing to wait a bit to get that data back
* And you can still downlink data normally 364 days a year - with one day scheduled for a Petabit scale transfer to the data "ferry"
This PDF is open access: https://arc.aiaa.org/doi/10.2514/1.A35091
And if you scroll through, there's some examples of "ugly" cyclers, which have a more interesting cadence and require a little bit of fuel to maintain.
By batching ugly cyclers, you can get multiple flybies, and not just constrained to the synodic cycles of the two planets. For example there's a 1-2 /year flyby schedule.