The Feasibility Study
The purpose of this study was to determine the feasibility of a series of twenty-four missions to profitably mine, refine, mint and return a total of 1480 metric tons of gold from 24 asteroids to Earth using the SpaceGold Mining Engine (SGME) concept.
The overall profit goals and objectives were provided as guidelines with the goal of determining whether such a mission could be accomplished within a mission cost cap of $150 million development cost over sixteen months and $20 million build, launch and operating cost over an additional twenty-four months for a total program budget of $630 million over a 40 month campaign period.
Once SGME is in place they will continue to operate for 31 years nominally returning 2 tons of refined gold per year by sample return capsule once every three years. The current value of the gold returned by this campaign is $69.84 billion. The value of 48 tons of refined gold per year over 31 years, when discounted at 2%, is $51.95 billion. This study was conducted by Hamidreza Jalilian and SpaceGold Executive Team and leveraged previous mission analysis, trades, and options for concepts developed by this team since 2017.
The SpaceGold Mining Engine concept involves placing a lander and rover (with a mining payload) on an asteroid surface. The rover will carry a suite of scientific instruments to investigate the location, composition, and state of asteroid regolith along with machinery to mine, refine and mint gold bars in-situ. While previously during asteroid approach instruments provide data that support the locating of gold outcroppings existing in the asteroid, this SGME concept seeks to understand the nature of those deposits by direct in-situ measurement and then mine them using a powerful solar pumped laser.
Then refine the gold and mint 0.1 troy ounce gold bars in-situ. A prospecting strategy is employed using powerful lasers to enable lateral and vertical sampling only where higher gold concentrations are detected, thus eliminating the criticality of statistically significant numbers and distributions of samples required by stochastic approaches. The SGME concept’s deterministic prospecting approach eliminates the need for stochastic sampling strategies.
Both a basic and robust instrument suite was developed to meet the profit objectives by priorities developed in subsequent discussions with the mission concept’s Executive Team. The complete set of instruments includes MEMS-based: neutron spectrometers, downhole imaging, a gas chromatograph/mass spectrometer, x-ray diffraction, exospheric deposits measurement, surface imaging and a laser drill/sample acquisition system for obtaining samples.
Laser energy is received by the lander and focused on asteroid regolith with high gold content and the resulting plasma plume is processed by the lander to cause refined gold to be deposited on a glass ribbon which is then wound into on of twelve return capsules. When each capsule is filled the laser is then used to propel the capsule back to Earth where it is recovered at Holloman AFB. The spacecraft is launched on a single SpaceX Falcon 9 Launch Vehicle as a Rideshare payload.
In order to ensure mission cost caps would be met, this mission concept utilizes a lander to deliver a laser-powered rover to the surface. The lander is of a minimal capability, making use of a high thrust-to-weight ratio advanced photonic propulsion system for landing but relying on rover-based avionics and sensors to the maximum extent to enable precision landing in a gold-rich region of an asteroid.
The lander would be nonfunctional after the rover departs with the instrument suite to prospect for and mine deposits, yet leaving open the possibility of rover return and lander reuse allowing the system to hop around an asteroid and even between asteroids. The rover carries the power system (laser receiver) as well as all of the instruments and return capsules. The laser power system supports unlimited surface operations, accomplishing profit objectives within laser sight restrictions (e.g., not surveying the lateral distribution area suggested by the Executive ground rules).
The laser-powered rover enables thirty-one years of surface operations that accomplish all profit objectives. A reduced Laser instrument suite and mission duration were also considered that fully met all profit objectives within the Executive cost cap. The development of the SGME mission would start in FY2020 for an FY2022 launch. Total mission costs vary with the Rover’s power system and instrument configurations.
The base laser rover mission with a full instrument complement costs $630 million, the expanded laser rover mission costs $910 million, (all in FY19 dollars, including reserves). SpaceGold Mining Engine Mission Concept Study 1 1. Profit Objectives Profit Questions and Objectives The asteroids have long been known to be rich in gold deposits due to the low gravity of asteroids during their formation. Earth’s crust is deficient in gold because early in its gold distribution the Earth was fully molten and heavy materials like gold sank to the center.
Gold found on Earth’s surface comes from bolide strikes originally. Additionally, it has long been known that gold deposits on Earth are associated with bolide strikes. The gold deposits are of interest because they average 5.54 ppm by atom on ‘O’ type asteroids, which translates to 18.2 grams/ton which is consistent with gold ores found on Earth. Commercial ores on Earth have as little as 1 gram/ton of gold.
Thus asteroid regolith has the potential to be richer than most remaining high-grade ores on Earth. Several studies have provided data that support the possibility of gold deposits in the asteroids. USGS survey of meteorites found on Earth (Jones, 1968) and another USGS survey involving spectroscopic studies of meteor showers (Mason, 1979).
The next stage in understanding gold deposits is to determine the species and their form and distribution (both horizontally and vertically); those determinations must be made in situ and when high-value gold ore is found, processed and refined gold returned to Earth at the greatest possible rate using laser energy.
Our current knowledge is limited to knowing that deposits exist in some form in the asteroid. The goals of SGME are to determine the gold-bearing species, their form, and their distribution and maximize gold production in this first campaign. The Executive Team defined the fundamental profit questions to be addressed by the SGME mission:
1. What is the lateral and vertical distribution of the gold deposits?
2. What is the chemical composition and variability of gold deposits?
3. What is the isotopic composition of the deposits?
4. What is the physical form of the deposits?
5. What is the concentration of the current gold deposits?
Regolith with an average concentration of 5.54 ppm by atom, or 18.2 g/ton by mass when maintained, permits a rate of refined gold production of 63.42 mg/s by processing with a laser 3.845 kg/s of regolith. Studies done with laser beam processing of rock by the USGS (Leong, 2003) indicate laser is required for processing 2 tons per year of refined gold (64,401.49 troy ounces) worth $94.38 million per year. $2,164.86 million net present value discounted at 2%. $2,925.78 million total value over 31 years of production, typical of the best terrestrial mines.
Maximizing specific production per watt of laser energy is critical to long term profitability. Our current knowledge is limited to knowing that deposits exist in some form in the asteroid. The goals of SGME are to determine the gold-bearing species, their form, and their distribution and maximize gold production in this first campaign.
The Executive Team identified a series of five specific Profit Objectives that address the five fundamental Profit Questions regarding gold deposits in the asteroid. The primary objectives are to constrain the location, composition, and state of the deposits. The Profit Objectives for the SpaceGold Mining Engine mission concept are achieved through a series of measurements made by the scientific payload package followed by operation of the gold acquisition system which fills the gold return capsule. The instruments considered for this concept include the following: Rover neutron spectrometer Laser drill capable of penetrating 2 meters Gold acquisition system Downhole neutron spectrometer Downhole imager Gas chromatograph / mass spectrometer (Laser plasma MS) X-ray diffraction Ground penetrating radar Exosphere mass spectrometer.
In order to significantly advance our understanding of asteroid gold deposits and what they can tell us about asteroid and solar system gold distribution, a mission capable of extensive surface exploration is required as numerous samples must be obtained, analyzed and refined in-situ.
We do not understand the manner in which gold species are formed on asteroids, nor how they evolve, once exposed on the surface of an asteroid. Since orbital remote sensing data acquired during the approach does not have the resolution to map the quality of deposits exposed on the surface, we do not understand how they are spatially distributed (in either the horizontal or vertical dimension). Therefore, the surface must be explored to map the distribution of gold to isolate the most productive regions.
As noted, since we do not understand the spatial distribution, we do not know a priori where to sample. The sampling strategy defined as part of this study relies on a neutron spectrometer to locate areas of high Au content that would indicate Au-bearing deposits.
To allow high spatial resolution and detection of low concentrations, and to map the Au-bearing areas with sufficient resolution to determine where to sample, the instrument must be in close proximity to the surface and cross the surface at a relatively low velocity.
These requirements are best fulfilled by a rover. The instrument suite identified in the study provides the data necessary to obtain the appropriate samples to answer these questions. First, the rover neutron spectrometer provides information about the lateral extent of the gold deposits.
Additionally, it is used to optimize the laser drilling location. Next, the laser drill provides access to the upper two meters of the regolith, the upper part of the regolith that is most likely to contain gold species. Once a borehole has been laser drilled, several instruments make measurements within it. The downhole imager will look at the physical state of the deposits, while the downhole neutron spectrometer will measure both the vertical variability and also help determine the best place to sample.
Finally, a sample acquisition system will bring samples from chosen depths to the rover for analysis by the laser-plasma MS. The Laser plasma MS will determine the chemical and isotopic composition of the deposits.