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There it is. The elusive Ersa 772. Filled with an estimated $15 trillion in precious metals, mining that asteroid could make you the richest man on this side of the galaxy. You have all of the funds and resources you need to get your hands on that asteroid: a crew of 20 veteran astronauts and space explorers, 100 billion USD in funds, and all of the technology needed to extract the metal from the asteroid. Assume 22nd century technology, and assume that something like a space tent has been invented, and it can moderate temperature, and hold about 50 people comfortably for about 10 years because somehow future humans have solved the problem of sustaining humans in space for long periods of time.

There's just one problem: you don't have a spacecraft to get there. However, you're in luck, as your chief scientist informs you that asteroid Chariclo 101, which is about 200 miles in diameter travelling at about 60000 mph, is expected to come very close to impacting Ersa 772.

Would it be feasible to hitch a free ride on Chariclo 101? Remember, we have a "space tent" (which takes up about 1.5 square miles) that can sustain humans, so is there really any reason this wouldn't work?

Edit: Hope this helps

Solar System diagram showing current and future positions

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    $\begingroup$ The big problem with space travel is delta-v, and the delta-v will probably be far higher for such an intermediate path than for travelling directly. (It will definitely be at least slightly higher, because following Chariclo's orbit is one possible path of getting to Ersa, and you'd have to expend extra energy for takeoff and landing.) But yes, if you have a space-tent that can only be set-up at an asteroid - in other word, if you do have a spacecraft, but its life-support sucks, and has to be refueled - this is indeed quite a reasonable possibility. $\endgroup$ – January First-of-May Mar 22 '16 at 0:09
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    $\begingroup$ I guess what I'm not seeing is any reason you can't. But you've very carefully explained the question, so I suspect you are concerned about some specific difficulties. Can you add them? Otherwise I think the answer is "yes." $\endgroup$ – CAgrippa Mar 22 '16 at 0:09
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    $\begingroup$ I suspect to accelerate to catch an asteroid, you have acheived the acceleration you need to match an asteroid's speed, no? $\endgroup$ – Mikey Mar 22 '16 at 0:13
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    $\begingroup$ On asteroids going off course in the deep abyss of space... are you silly? Asteroids do not work that way (especially big ones). They do move constantly, sure, but this movement is already known to within a few kilometers in several years; otherwise stuff like the Rosetta mission would've been impossible. This only becomes easier with 22nd century computing technology. (And I would've probably made an answer out of all this, but I'm tired, shouldn't really be at a computer in the first place, and due to wake up in 3.5 hours; if this is still open 4-5 hours later, I'll post an answer.) $\endgroup$ – January First-of-May Mar 22 '16 at 0:24
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    $\begingroup$ I think there's a second question implicit here. "Would it be possible to stop an asteroid?" $\endgroup$ – Separatrix Mar 22 '16 at 12:30
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Feasible, but inefficient, and needlessly complicated. It costs more to change orbits to rendezvous with Chariclo, then change orbits again to rendezvous with Ersa, then to just go straight to Ersa. Why? Delta-V and inertia.

Your setup has a few problems, you say Chariclo 101 is going 60,000 mph, but relative to what? The Earth is going around the Sun at 66,600 mph, so you probably don't mean orbital velocity. From your drawing it looks like Ersa is making about 1/6th its orbit during the trip. Asteroid belt objects have an orbital period of about 4.5 years which means the trip will take about 275 days.

The details don't really matter, there's an asteroid whizzing by your starting point that will later whizz by your stopping point.

The problem with your plan is velocity is not the problem in space flight. Once you're up to speed in space you can coast along pretty much forever. Changing velocity is, and your plan just adds more changes. Not just absolute velocity, but also direction. This is known as delta-V. This means changing your orbit costs fuel, and each rendezvous requires delta-v. Even in the 22nd century delta-V matters (and if it doesn't, why do we need this convoluted plan?).

Then there's the issue with your spaceship. Any spaceship which can rendezvous with and land on Chariclo then ride it to Erza, can more easily rendezvous with and land on Erza. You need a spaceship large enough to carry all your people and all their supplies for the trip and mining colony. You need fuel to leave LEO and rendezvous with Charicio, plus fuel to leave Charicio and rendezvous with Erza. You need supplies for the trip. If you already have a spaceship large enough to carry everything and everyone to Charicio and wait until it reaches Erza, why not just take it all the way to Erza?

To sum up, the Chariclo plan means you have to...

  • Leave LEO in a spaceship sufficiently large to carry all your people and consumables for the whole trip.
  • Go to where Chariclo 101 will be.
  • Change velocity and direction to match its orbit and rendezvous, which means you're going as fast as Chariclo.
  • Find a suitable landing spot.
  • Land on it.
  • Set up camp.
  • Wait and consume resources.
  • Tear down camp.
  • Lift off from it.
  • Change velocity and direction to rendezvous with Ersa 772.
  • Find a suitable landing spot.
  • Land on Ersa 772.
  • Set up camp again.
  • Start mining.

All that extra changing in velocity to rendezvous and land on Chariclo is unnecessary. Just take a more efficient direct transfer orbit to Ersa in your spaceship which already has to hold everyone and everything and already needs the fuel to have the delta-V to reach an object which will pass Ersa.

  • Leave LEO in a spaceship sufficiently large to carry all your people and consumables for the whole trip.
  • Change velocity and direction to rendezvous with Ersa 772.
  • Wait and consume resources.
  • Find a suitable landing spot.
  • Land on Ersa 772.
  • Set up camp.
  • Start mining.

This allows you to pick a more efficient, direct transfer orbit, and at the time of your choosing. It removes the cost and complexity of an extra rendezvous, landing, and liftoff.

This assumes there's no consumables on Chariclo. If there are (such as mineable air, water, fuel, and reaction mass) it might make the landing worthwhile. If you can "live off the land" for the 9 month trip it will greatly reduce the amount of supplies your spaceship must carry, and thus reduce its size and complexity.

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Schwern's answer is the correct one for the specific question that you asked.

However, there is a situation in which something similar to what you describe might be both feasible and desirable.

Aldrin Cycler

The problem

Space is very hostile to human life - deadly radiation, zero-G, energy production, food production, oxygen production, water production. Also the general environment of space habitats leave much to be desired from a psychological perspective - living space.

The reason those things pose such hurdles to space travel is the fact that every gram you take with you often costs 2 grams (or more, sometimes much more) in fuel you need to bring with you for your mission.

The solution

Imagine a situation in which you could bring as much mass as you wanted for your mission without it costing you anything in your fuel budget.

Aldrin proposes a pair of Mars cycler vehicles providing regular transport between Earth and Mars.[3] One cycler would travel an outbound route from Earth to Mars in about five months. Another Mars cycler in a complementary trajectory would travel from Mars to Earth, also in about five months. Taxi and cargo vehicles would attach to the cycler at one planet and detach upon reaching the other.

When to use it

When you plan to have a series of missions between two orbits in a Stellar System, you could set up an orbit that cycled between those two orbits.

Your cycler would contain all the massive equipment required (or desired) for long-duration space missions (radiation shields, closed loop life support, centrifuges, extra living space, etc.). The cycler would NOT perform any maneuvering (other than perhaps minor station keeping) and therefore, would not require much fuel for changing its $\Delta V$.

A mission taxi would launch the crew and time sensitive cargoes to the rendezvous & dock with the cycler. The crew would live on the cycler on the outbound/inbound portion of the journey. The mission taxi would provide the $\Delta V$ required to put the crew and cargo into a capture orbit around the destination.

The mission taxi could bring limited shielding, life support, etc.

The over all mission might save tremendous amounts of money by doing things this way but only if they planned on repeated voyages between the two bodies.

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Schwern and Jim 2B have staked out the problems and possible solutions to your question, so I will add the main reason your protagonist might want to go with this plan: you need other resources.

Landing on Chariclo 101 gives you the ability to not only burrow into the asteroid for protection, but while you are on your way you can mine this asteroid for water, volatiles for the life support system and structural materials. If you have planned this properly, the initial expedition could be travelling "light" and build and stockpile much of the equipment and materials needed for the main mining expedition.

Consider that to send a fully equipped mining expedition directly to the asteroid and back requires fuel to accelerate to the asteroid's orbit; match orbits; accelerate back to Earth and then decelerate to LEO at least. Mining water for rocket fuel means you only need to bring enough fuel to get to Chariclo 101, a huge saving in mass. The same considerations hold for everything else. A direct shot to the main asteroid would require the Battlestar Galactica sized vessel, while mining Chariclo 101 could allow you to get away with a far smaller ship.

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  • $\begingroup$ I think this would be more feasible with a slower transit time. The 9 months I estimated for the trip doesn't give much time to setup (and tear down) shelter, mining, and processing operations to come out with a net consumables profit. However, the 3rd paragraph is incorrect; you need more fuel to rendezvous with Chariclo than with Ersa. This is the fundamental problem with the plan. Remember it's not about the distance it's about the delta-v. If Chariclo will reach and pass Ersa then it will cost more fuel to rendezvous with Chariclo than to rendezvous with Ersa. $\endgroup$ – Schwern Mar 23 '16 at 6:46

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