Mothership Mining Concept [Space Apps 2016]

Develop an approach for characterizing the composition of asteroid for mining potential and a process for mining different compositions. Explore a possible division of labor involving different types of vehicles (e.g. sensor units, drilling units, power gathering and distribution, extracted resources handling and transferring). Consider solutions for moving said asteroids between different orbits and/or consequently make periodical adjustments to keep them in place. Analyze how your idea would cope in some of the given scenarios or outline a scheme of your own.

1. Introduction

Society’s demand for industrial metals, rare-earth metals, and sustainable fuel components, are growing as we, the human race, further advance our technology and increase our population. The resources on Earth, however, will ultimately be unable to fuel mankind’s desire to advance and expand beyond Earth. Also it is no secret that mining activities on Earth have a significantly detrimental effect on the ecosystem. The idea of asteroid mining is to utilize the billions of dollars worth of untapped resources of the solar system. Utilization of such minimizes environmental degradation and further expands humanity’s progress.

Asteroid mining requires heavy investment but given the potential returns, industries would not hesitate to invest once a sound approach is established. Moreover, the trend of reusable launch vehicles and abundance of asteroids in our solar system will no doubt make efforts significantly more reasonable.

An asteroid mining system is proposed. The system is composed of a mothership that acts as a host for different bots as well as a reservoir for the mined resources. The mothership is complemented with an extractor ship that exchanges fuel with mined ores. The roles of the bots, namely the scouts & miners, and the mining procedure are explained below. Furthermore, the bots and machinery are proposed to be semi-autonomous with minimal human intervention due to the great time it takes to send & receive information from the Earth to the mining system and vice versa.

2. Methodology

a. Mothership

A mothership is proposed to house the different bots (scouts, miners, repair bots) and machinery (material segregator, spectrophotometers) for the duration of the expedition. The mothership also possesses long range spectrophotometers to primarily scout the resource contents on the surface of the prospective asteroids. Repair bots are installed inside for the maintenance and repair of the scouts and the miners. Furthermore, the mothership will be the reservoir for the collected resources until the extractor arrives to get the payload. The construction of the mothership is proposed to mimic the construction of the International Space Station (ISS). Manufacturing of the different bots and parts of the mothership would be done on Earth and its assembly would be done in space. The mothership would be equipped with several types of thrusters in order to arrive and hover on the designated place in space. Solar panels are installed to not only supply the additional energy requirements of the bots and machinery but also to store energy in case of emergencies.

b. Scout

The scout will be a cylindrical shaped bot equipped with a long retractable diamond-tipped, small-diameter coring drill in order to take samples from below the surface of the asteroid. Additionally, adaptive limbs with diamond-tipped drills on the tips act as anchor. Moreover, inside the bot is an integrated Energy Dispersive X-Ray Spectrometer (EDX) for the analysis and determination of the retrieved materials.

c. Miner

Two (2) types of miners are proposed:(1) surface miner, and (2) underground extractors. The surface miner’s design is similar to that of the proposed scout design but a modified jackhammer and “catcher” is used in place of the retractable coring drill. The jackhammer is a modified high-frequency piston that exploits the resonant frequency of the material to be retrieved. Moreover, the jackhammer is a “smart-machine” and adjusts its output frequency depending on the surface. The jackhammer and catcher is designed to be powerful enough to slowly demolish and collect the asteroid rocks without the risk of orbital alteration or formation of large debris. Consequently, the underground extractors are large miners that utilizes adaptive robotic limbs with miniature diamond-tipped drill anchors and diamond-tipped coring drills with a large diameter to retrieve any desired material deep under the surface. The use of diamond tipped drills is necessary to penetrate hard substances (rocks or metals).

d. Material Segregator

Installed inside the mothership, the role of the material segregator is to classify and separate the retrieved resources by the underground extractors. Modified jackhammers are installed on the segregator in order to break up the different materials found in the sample. Spectrophotometers are attached in order to classify the different materials present on the sample. Moreover, claws are used to isolate the identified materials to their respective categories.

e. Extractor (/fuel ship)

The role of the extractor is to resupply the mothership with fuel and to retrieve the mined resources back to Earth. The extractor would be fully reusable for multiple retrieval missions.

f. Mining Process

The mining process fully depends on the placement of the desired material. Surface mining would primarily be done by modified jackhammers attached to the surface miner. These jackhammers are high-frequency pistons that can adjust to match the resonant frequency of the material to be mined. While underground extraction would utilize giant diamond-tipped coring drills.

g. Retrieval Process

Unmanned extractors are sent from Earth to the mothership to retrieve the mined asteroid resources. These extractors are suggested to utilize the concept of reusable rockets, similar to that made by SpaceX, to minimize expenses.

The unmanned extractors carry a surplus of propellants for the mothership. As the extractor docks with the mothership, fuel and ores are exchanged. The extractor returns to Earth for mineral refining.

3. Classification of Asteroids

Near-earth asteroids (NEAs) are classified into three(3) separate subsets: Apollos, Amors, and Atens. Among the subsets, Atens type NEAs does not only have the smallest orbits but also crosses the orbit of Earth. Given the proximity of the orbital path of the Atens type NEAs to that of Earth’s, Atens type NEAs are considered to be the most accessible for asteroid mining. Although it is worth to note that Apollos type NEAs also have an orbit that cross that of Earth, but its full orbital period is significantly longer than that of the Atens type which makes the interception of these asteroids and mineable windows considerably longer.

Asteroids are generally classified into 3 groups, namely: c-type (carbonaceous), s-type (stony), m-type (metallic). C-type asteroids contain water and high contents of opaque carbonaceous material. S-type asteroids are anhydrous and rocky; they contain silicates, sulfides, and metals. M-type asteroids have higher density metals, they have a high radar reflectivity that is characteristic to metals such as iron, nickel, and cobalt. The table below shows a sample composition for each type of asteroid compared to lunar regolith.

4. Propulsion Requirements

As compared to the moon and the satellites of Mars, NEAs are considered to be an ideal choice for extraterrestrial mining due to the relatively low propulsion requirement for landing and takeoff. The low propulsion requirement implies the efficient management of fuel/energy of the scouts and miners while landing or escaping the gravitational pull of these asteroids. The relatively low gravitational force of the asteroids is correlated to the amount of mass present. Most NEAs are about 1km in diameter. Despite its size, one(1) metallic NEA may have a platinum-group metal abundance greater than the whole supply present/used on Earth.

For a full scale mining expedition, the mothership would carry a surplus of fuel/propellants that would account for possible hindrances. In the event of fuel shortage, extractors could be sent to refuel the mothership.

5. Minerals and Metals present on an Asteroid

Asteroids, depending on its type (Carbonaceous, Stony, or Metallic), may contain volatiles in the form of H2O or carbonaceous chondrites. Several industrial metals such as Iron, Nickel, & Cobalt, as well as rare-earth metals like Platinum, Ruthenium, & Palladium are relatively abundant in metallic asteroids, see the figure below for more details.

Materials present in asteroids can support the increasing demand of society’s technological advancement. Metallic asteroids are considered to be the most important because of its abundance of platinum-group metals, which are otherwise scarce on Earth. Volatiles, on the other hand, are broken down to make efficient rocket fuel needed for space exploration and expeditions.

6. Value of Minerals and Metals

In a 2001 study by Shane Ross, The estimated earnings per year for semiconductors materials would be $11B whereas for precious metals, $14B.

In a 2012 study by Space Wealth, they estimate that a 200m diameter asteroid that is mineralogically similar with the most common types of observed meteorites with platinum group metals (PGM) that has an abundance of ~4.5ppm with a density of 1.95g/cm3, has a value of over $1B per asteroid. It is worth noting that a year of PGM sales in 2009 generates $17B worth of demand. The figure below lists the estimated composition and market value of such asteroids .

Denser PGM asteroids, having ~90ppm, have a value of $26B per asteroid. The figure below shows an example of such an asteroid.

7. Conclusions

Reusable extractors and a sustainable mothership are proposed in order to maximize profitability. However, return of investment (ROI) is expected to come after a few years or so due to the nature of the project. Some asteroids have been given market values varying from a few billion to a few trillions of dollars due to the varying richness of compounds and minerals detected. Nevertheless, travel time, scouting time, mining time, and retrieval time would determine when the ROI would be achieved. Asteroid mining would not only supply the demand for advancement, but also help preserve Earth’s ecosystem by providing a mining substitute as well as pave the way for humanity to further understand and explore the solar system.

8. References

1.Crandall WBC, Gorman L, Howard P, von der Dunk F, Elvis M, Lauretta D, Puig-Suari J, Sonter M. Profitable Asteroid Mining: A Pragmatic Policy Goal? Space Wealth: Profitable Space, Sustainable Earth. 2012 Jul 20. Available from http://www.spacewealth.org/files/P@M-Pragmatic-2012-07-20.pdf

2.Ross SD. Near-Earth Asteroid Mining, Space Industry Report.California Institute of Technology. 2001 Dec 14. Available from http://www.nss.org/settlement/asteroids/NearEarthAsteroidMining(Ross2001).pdf

3.Accenture. Courage or Capital: The final obstacles for sustainable asteroid mining. 2015 Aug. Available from https://www.accenture.com/_acnmedia/Accenture/Conversion-Assets/DotCom/Documents/Global/PDF/Dualpub_21/Accenture-POV-NaturalResources-Aug2015-Sustainable-Asteroid-Mining.pdf

4.Erickson KR. Optimal Architecture for an Asteroid Mining Mission: Equipment Details and Integration. American Institute of Aeronautics and Astronautics. 2006 Sep. Available from: http://arc.aiaa.org/doi/abs/10.2514/6.2006-7504

5.Wei L, Tie Y, Siqi L, Xiaoning Z. Rock fragmentation mechanisms and an experimental study of drilling tools during high-frequency harmonic vibration. Petroleum Science. 2013 Jun: 10(2), 205-211. Available from: http://link.springer.com/article/10.1007%2Fs12182-013-0268-3

6.Sonter MJ. The technical and economic feasibility of mining the near-earht asteroids. Master of Science (Hons.) thesis. University of Wollongong, Department of Physics. 1996. Available from http://ro.uow.edu.au/theses/2862/

7.National Aeronautics Space Administration. Advanced Exploration Systems: Resource Prospector. Available from https://www.nasa.gov/resource-prospector.

8.International Astronomical Union: Minor Planet Center. Forthcoming Close Approaches To The Earth. Available from: http://www.minorplanetcenter.net/iau/lists/CloseApp.html.

9.Waugh R. Single asteroid worth £60 trillion if it was mined - as much as the world earns in a year. Mail Online. 2012 May 21. Available from: http://www.dailymail.co.uk/sciencetech/article-2147404/Found-The-single-asteroid-thats-worth-60-billion-years-financial-output-entire-WORLD.html.

10.Grush L. SpaceX’s reusable rockets will make space cheaper - but how much? The Verge. 2015 Dec 24. Available from http://www.theverge.com/2015/12/24/10661544/spacex-reusable-rocket-refurbishment-repair-design-cost-falcon-9.

11.Atkinson N. Astronomy Guide to Space: What are asteroids made of? Universe Today. 2015 Sep 12. Available from: http://www.universetoday.com/37425/what-are-asteroids-made-of/.

12.Planetary Resources. Asteroids Will Unlock The Solar System’s Economy. Available from http://www.planetaryresources.com/asteroids/#asteroid-targets.