if and when we’ve ever gotten an asteroid mining industry off the ground, one of the biggest decisions to make in the structure of any asteroid mining mission would be how to get the resources where all of our other infrastructure is – somewhere around the Earth.
This decision will usually focus on one of two propulsion methodologies – chemical rockets, like the ones we already use to get us into space in the first place, or solar sails, which, although slower and unable to put us into orbit, don’t. need fuel. So which propulsion methodology is best for these future missions? A study by researchers at the University of Glasgow looked at both of these scenarios and came up with a clear answer: solar sails.
The economics of asteroid mining
To answer this type of theoretical questions, it is essential to impose limits on the answers. For example, billions of asteroids exist in the solar system, so it’s more realistic to only look at those known as near-Earth asteroids (NEAs). But even so, there are over 30,000 known NEAs. It would have been impossible for lead author Merel Vergaaij, then a Ph.D. university student, and her colleagues to calculate optimized trajectories for each of them.
So they divided the area around the Earth into generalized orbital parameters – distance from the major semi-axis, eccentricity and inclination. With these three parameters, it is easier to get an idea of what a general transfer orbit would look like for a given asteroid in this region of space, some of which would be quite close to Earth in its orbital path.
Other constraints were also needed, such as calculating only the cost and benefits of transferring material from the asteroid, not extracting the asteroid itself. The setup and installation of mining equipment was considered beyond the scope of this article. Additionally, there had to be a wait time on the asteroid itself for the returning mission to have time to stock up on the material it would be carrying.
This material, in this calculation, was volatile. Volatiles, such as water, have been at the center of discussions of asteroid mining, as they are the basis for the rocket fuel that would be needed to explore further into the solar system and would cost a lot of money to bring it from Earth itself. Additionally, chemical rockets can then use some of these volatiles as their own fuel to return to the Earth system.
A few more constraints have come into place, including returning volatiles to geostationary orbit (GEO), making some assumptions about launch costs based on projected Starship costs, and determining that all-important metric of economic studies – present value. net (NPV ).
The NPV is the outcome on which the solutions would be judged and based on various calculated factors. These would include a variety of costs, such as launch costs, development costs, manufacturing costs, and operational costs. Revenues would be calculated based on the expected value of volatiles delivered into orbit. When the revenue exceeds the cost of the mission, the NPV becomes positive, which in this case indicates whether a mission to an asteroid in that area is worth it.
To make this determination, the authors used a technique called genetic algorithm to solve an optimization problem. Essentially, they gave the algorithm a bunch of parameters, such as orbital mechanics, spacecraft masses, and the amount of volatiles returned, and told the algorithm to optimize for the most important NPV value. The result of the algorithm was very clear: solar sails have positive NPVs for a wider variety of areas in near-Earth space.
Solar sails prevail
This was mainly due to certain weaknesses of chemical rockets. They had to use some of their delivered hardware to get back to GEO. And, while the time of their transfer orbit was shorter, another factor in the NPV, the discount rate, which decreases the amount of expected value of a resource the more it is sold in the future, does not take into account. not enough of the value of what the solar sail can bring back that would make it on par with the chemical rocket.
There were still certain areas of near-Earth space in which even solar sails were unprofitable, so the authors suggest that future asteroid miners look at asteroids in specific regions they call as potentially profitable if they are looking for their first major mining site. . Additionally, the researchers made a few changes to their original base mission structure, such as stopping at a lunar gateway, adding a second trip, and running a series of variable simulations, called Monte Carlo simulations, that would test in how cost-effective these different schemes were.
Both add a second trip and stop at the Lunar Gateway rather than GEO added significant value to each type of mission architecture. Monte Carlo simulations also showed that their profitability was compatible with small variations in input costs and output revenues. Overall, while there are potentially profitable targets for each type of propulsion system, it seems that solar sails are the clear winner of both. Now it’s up to those hoping to build the first asteroid mining empire to listen.
This article was originally published on Universe today by Andy Tomaswick. Read the original article here.