Coupled trajectory and economic analysis of asteroid resources

To reduce the cost of space missions, asteroid resources have gained significant attention. By using resources from asteroids, water for example, expensive launches from Earth can be minimised. Water obtained from asteroids holds great potential, not just for human life support, but split in its constituents it forms a highly effective propellant: liquid oxygen and liquid hydrogen. This means that asteroid resources can be used as building blocks for sustainable in-space infrastructure to aid with interplanetary exploration. Several commercial companies have expressed interest in pursuing asteroid mining. This fuels the need for cost estimations and economic models for asteroid mining, as both public and private ventures need to be convinced of the profitability of asteroid mining before investing in expensive space missions. To investigate the profitability of asteroid mining missions, this thesis has integrated economic modelling and trajectory optimisation at an appropriate level of detail and accuracy for each. Due to the coupling of the economic model and trajectory optimisation, trajectories can be designed for cost objectives rather than the more traditional minimum time and minimum propellant objectives. A parametric model has been developed, which can be used to investigate different mining missions, focused on but not limited to asteroid mining. Using this economic model and mission analysis, applied to a range of different missions with varying customer and mining locations, allows for an impartial comparison of the different missions. Potentially profitable value chains can be identified, influential parameters in the model can be found (e.g., certain cost estimates), or trade-offs between variations in mission architectures can be carried out. Using the model, a trade-off between chemical propulsion and solar sailing to transport asteroid resources has shown that while solar sails have the great advantage that they do not require any propellant, long mission durations have a significant impact on the Net Present Value and Internal Rate of Return, causing these missions to be not competitive with missions utilising chemical propulsion to transport asteroid resources to Earth orbit (e.g., geostationary orbit). A key finding is the importance of accurate specific launch costs in economic models for asteroid mining. Where other economic models often include specific launch costs in the order of 10,000 $/kg, commercial launch providers are driving down these costs by orders of magnitude by decreasing launch costs and increasing payload capacity. It is shown that this significantly impacts the profitability of asteroid mining, which can only sell resources at a price that is competitive with launching the same resources from the Earth. Assuming high specific launch costs therefore results in overestimating the profitability of asteroid mining. Another essential conclusion is that for any in-space propellant customer beyond low-Earth orbit, off-Earth mining (e.g., on asteroids, the Moon or Mars) can bring down the cost, mass and risk of future human and robotic space missions. While asteroid mining cannot compete financially with resources mined and processed on the same surface as customers (e.g., on the Moon or Mars), asteroids are likely to financially compete with other sources for customers in geostationary orbit, Sun-Earth or Sun-Mars Lagrange points, in orbit around or near the Moon or Mars, or in the main asteroid belt. Finally, it is shown that in a thriving space propellant economy with in-space propellant depots, near-Earth asteroids will be the first asteroids to run out of volatiles, due to their attractive orbits and small size. While asteroid resources are not expected to run out for a long time, this is mainly due to the wealth of resources in main-belt asteroids, which are expensive to mine, especially to supply a depot near Earth. These findings indicate the need for an international regulatory organisation allocating asteroid resources, either to preserve resources for future generations, or to reserve resources for use near Earth

Influence of launcher cost and payload capacity on asteroid mining profitability

A range of resources can be extracted from asteroids, for example volatiles for propellant and consumables for (crewed) spacecraft, semi-conductors and metals for in-space manufacturing or platinum group metals for terrestrial use. One of the key justifications for in-situ manufacturing/resource utilisation is the high costs incurred during launch from the Earth’s deep gravity well. However, selling asteroid-derived resources in Earth orbit at a price competitive with launching the same resources from the Earth’s surface is largely dependent on specific launch costs, especially for low value-to-mass resources such as volatiles and construction materials. This paper investigates the influence of the cost and payload capacity of launch vehicles on asteroid mining profitability. Results demonstrate that for resources delivered to GEO, if the launch cost decreases, the specific launch cost (per kg) decreases in such a way that the decrease in total cost is smaller than the decrease in revenue, resulting in a less profitable mission. Similarly, when the payload capacity increases and therefore the specific launch cost decreases, the resulting mission also generates less profit. Sensitivity analyses show that for an example mission with two round trips to the same asteroid, profits increase with the increased number of trips, if the asteroid has not been fully depleted. Similarly, a further sensitivity analysis demonstrates that by changing the destination orbit for the processed resources to the Lunar Gateway, increased profit margins can be realised

Influence of Launcher Cost and Payload Capacity on Asteroid Mining Profitability

A range of resources can be extracted from asteroids, for example volatiles for propellant and consumables for (crewed) spacecraft, semi-conductors and metals for in-space manufacturing or platinum group metals for terrestrial use. One of the key justifications for in-situ manufacturing/resource utilisation is the high costs incurred during launch from the Earth’s deep gravity well. However, selling asteroid-derived resources in Earth orbit at a price competitive with launching the same resources from the Earth’s surface is largely dependent on specific launch costs, especially for low value-to-mass resources such as volatiles and construction materials. This paper investigates the influence of the cost and payload capacity of launch vehicles on asteroid mining profitability. Results demonstrate that for resources delivered to GEO, if the launch cost decreases, the specific launch cost (per kg) decreases in such a way that the decrease in total cost is smaller than the decrease in revenue, resulting in a less profitable mission. Similarly, when the payload capacity increases and therefore the specific launch cost decreases, the resulting mission also generates less profit. Sensitivity analyses show that for an example mission with two round trips to the same asteroid, profits increase with the increased number of trips, if the asteroid has not been fully depleted. Similarly, a further sensitivity analysis demonstrates that by changing the destination orbit for the processed resources to the Lunar Gateway, increased profit margins can be realised

Low-thrust: the fast & flexible path to Apophis

By the time of Apophis' fly-by on Friday, April 13th, 2029, more satellites than have ever been launched since the beginning of the space age to this day will reach low Earth orbit (LEO). Almost all of them will be microsatellites of less than ~250 kg equipped with solar-electric propulsion (SEP). We propose the use of already created low-thrust trajectories to Apophis to help advance design trades in the early study phases of missions to Apophis. It appears that small spacecraft missions could benefit from solar-electric or sail propulsion

More Bucks for the Bang: New Space Solutions, Impact Tourism and one Unique Science & Engineering Opportunity at T-6 Months and Counting

For now, the Planetary Defense Conference Exercise 2021's incoming fictitious(!) asteroid, 2021 PDC, seems headed for impact on October 20th, 2021, exactly 6 months after its discovery. Today (April 26th, 2021), the impact probability is 5%, in a steep rise from 1 in 2500 upon discovery six days ago. We all know how these things end. Or do we? Unless somebody kicked off another headline-grabbing media scare or wants to keep civil defense very idle very soon, chances are that it will hit (note: this is an exercise!). Taking stock, it is barely 6 months to impact, a steadily rising likelihood that it will actually happen, and a huge uncertainty of possible impact energies: First estimates range from 1.2 MtTNT to 13 GtTNT, and this is not even the worst-worst case: a 700 m diameter massive NiFe asteroid (covered by a thin veneer of Ryugu-black rubble to match size and brightness) would come in at 70 GtTNT. In down to Earth terms, this could be all between smashing fireworks over some remote area of the globe and a 7.5 km crater downtown somewhere. Considering the deliberate and sedate ways of development of interplanetary missions it seems we can only stand and stare until we know well enough where to tell people to pack up all that can be moved at all and save themselves. But then, it could just as well be a smaller bright rock. The best estimate is 120 m diameter from optical observation alone, by 13% standard albedo. NASA's upcoming DART mission to binary asteroid (65803) Didymos is designed to hit such a small target, its moonlet Dimorphos. The Deep Impact mission's impactor in 2005 successfully guided itself to the brightest spot on comet 9P/Tempel 1, a relatively small feature on the 6 km nucleus. And 'space' has changed: By the end of this decade, one satellite communication network plans to have launched over 11000 satellites at a pace of 60 per launch every other week. This level of series production is comparable in numbers to the most prolific commercial airliners. Launch vehicle production has not simply increased correspondingly - they can be reused, although in a trade for performance. Optical and radio astronomy as well as planetary radar have made great strides in the past decade, and so has the design and production capability for everyday 'high-tech' products. 60 years ago, spaceflight was invented from scratch within two years, and there are recent examples of fastpaced space projects as well as a drive towards 'responsive space'. It seems it is not quite yet time to abandon all hope. We present what could be done and what is too close to call once thinking is shoved out of the box by a clear and present danger, to show where a little more preparedness or routine would come in handy - or become decisive. And if we fail, let's stand and stare safely and well instrumented anywhere on Earth together in the greatest adventure of science

Flights Are Ten a Sail – Re-use and Commonality in the Design and System Engineering of Small Spacecraft Solar Sail Missions with Modular Hardware for Responsive and Adaptive Exploration

The exploration of small solar system bodies started with fast fly-bys of opportunity on the sidelines of missions to the planets. The tiny new worlds seen turned out to be so intriguing and different from all else(and each other) that dedicated sample-return and in-situ analysis missions were developed and launched. Through these, highly efficient low-thrust propulsion expanded from commercial use into mainstream and flagship science missions, there in combination with gravity assists. In parallel, the growth of small spacecraft solutions accelerated in numbers as well as individual spacecraft capabilities. The on-going missions OSIRIS-REx (NASA) or Hayabusa2 (JAXA) with its landers MINERVA-II and MASCOT, and the upcoming NEA scout mission are examples of this synergy of trends. The continuation of these and other related developments towards a propellant-less and highly efficient class of spacecraft for solar system exploration emerges in the form of small spacecraft solar sails designed for carefree handling and equipped with carried landers and application modules. These address the needs of all asteroid user communities– planetary science, planetary defence, and in-situ resource utilization – as well as other fields of solar system science and applications such as space weather warning and solar observations. Already the DLR-ESTEC GOSSAMER Roadmap for Solar Sailing initiated studies of missions uniquely feasible with solar sails such as Displaced L1 (DL1) space weather advance warning and monitoring and Solar Polar Orbiter(SPO) delivery, which demonstrate the capabilities of near-term solar sails to reach any kind of orbit in the inner solar system. This enables Multiple Near-Earth Asteroid (NEA) rendezvous missions (MNR),from Earth-coorbital to extremely inclined and even retrograde target orbits. For these mission types using separable payloads, design concepts can be derived from the separable Boom Sail Deployment Units characteristic of DLR GOSSAMER solar sail technology, nanolanders like MASCOT, or microlanders like the JAXA-DLR Jupiter Trojan Asteroid Lander for the OKEANOS mission which can shuttle from the sail to the targets visited and enable multiple NEA sample-return missions. These nanospacecraft scale components are an ideal match creating solar sails in micro-spacecraft format whose launch configurations are compatible with secondary payload platforms such as ESPA and ASAP. The DLR GOSSAMER solar sail technology builds on the experience gained in the development of deployable membrane structures leading up to the successful ground deployment test of a (20 m) solar sail at DLR Cologne in 1999 and in the 20 years since

Time-optimal solar sail transfers from Earth to pole-sitters at Mars and Venus

Recent studies have shown the feasibility of (quasi-)pole-sitter orbits at Mars and Venus, which involves a satellite positioned along or near the polar axis of a planet in order to have a continuous, hemispherical view of the planet's polar regions. In order to further demonstrate the feasibility of this mission concept, this thesis investigates time-optimal solar sail transfers to these (quasi-)pole-sitters. In particular, (quasi-)pole-sitters which are achievable when assuming solar sail technology expected in a near- to mid-term time-frame. To reduce mission operational cost, the objective of this research is to minimize the time required for the transfer, which requires the solution to an optimal control problem. Initial guess solutions for this optimal control problem are provided through two completely different techniques, in order to compare and validate the individual performances: first, a technique derived from dynamical systems theory (a type of grid search) and second, a genetic algorithm. Subsequent optimization using a direct pseudospectral algorithm results in time-optimal transfers to the considered Mars (quasi-)pole-sitters that span 2.61 and 2.72 years, and 1.07 and 1.19 years to the considered Venus (quasi-)pole-sitters. Effects due to variations in performance of the ideal sail, non-ideal sail properties, and Earth departure orbit are investigated. In addition, this paper demonstrates that a genetic algorithm is well suited to generate initial guesses for similar interplanetary transfers in the inner solar system. It provides initial guesses that outperform the more conventional grid search technique, in terms of feasibility of the initial guess transfers, as well as in computation time and ease of implementation.Aerospace Engineering | Astrodynamics & Space Mission

End-to-end trajectory design for a solar-sail-only pole-sitter at Venus, Earth, and Mars

The concept of a pole-sitter has been under investigation for many years, showing the capability of a low-thrust propulsion system to maintain a spacecraft at a static position along a planet’s polar axis. From such a position, the spacecraft has a view of the planet’s polar regions equivalent to that of the low- and mid-latitudes from geostationary orbit. Previous work has hinted at the existence of pole-sitters that would only require a solar sail to provide the necessary propulsive thrust if a slight deviation from a position exactly along the polar axis is allowed, without compromising on the continuous view of the planet’s polar region (a so-called quasi-pole-sitter). This paper conducts a further in-depth analysis of these high-potential solar-sail-only quasi-pole-sitters and presents a full end-to-end trajectory design: from launch and transfer to orbit design and orbit control. The results are the next steppingstone towards strengthening the feasibility and utility of these orbits for continuous planetary polar observation

End-to-end Trajectory Design for a Solar-sail-only Pole-sitter at Venus, Earth, and Mars

The concept of a pole-sitter has been under investigation for many years, showing the capability of a low-thrust propulsion system to maintain a static position along a planet’s polar axis. Such a position provides a view of the planet’s polar regions equivalent to that of the low- and mid-latitudes from geostationary orbit. Previous work has hinted at the existence of pole-sitters that would only require a solar sail to provide the necessary propulsive thrust if a slight movement around the polar axis is allowed, without compromising on the continuous view of the planet’s polar region (a so-called quasi-pole-sitter). This paper conducts a further in-depth analysis of these high-potential solar-sail-only quasi-pole-sitters and presents a full end-to-end trajectory design: from launch and transfer to orbit design and orbit control. The results are the next stepping stone towards strengthening the feasibility and utility of these orbits for continuous planetary polar observation

Influence of launcher cost and payload capacity on asteroid mining profitability

A range of resources can be extracted from asteroids, for example volatiles for propellant and consumables for (crewed) spacecraft, semi-conductors and metals for in-space manufacturing or platinum group metals for terrestrial use. One of the key justifications for in-situ manufacturing/resource utilisation is the high costs incurred during launch from the Earth’s deep gravity well. However, selling asteroid-derived resources in Earth orbit at a price competitive with launching the same resources from the Earth’s surface is largely dependent on specific launch costs, especially for low value-to-mass resources such as volatiles and construction materials. This paper investigates the influence of the cost and payload capacity of launch vehicles on asteroid mining profitability. Results demonstrate that for resources delivered to GEO, if the launch cost decreases, the specific launch cost (per kg) decreases in such a way that the decrease in total cost is smaller than the decrease in revenue, resulting in a less profitable mission. Similarly, when the payload capacity increases and therefore the specific launch cost decreases, the resulting mission also generates less profit. Sensitivity analyses show that for an example mission with two round trips to the same asteroid, profits increase with the increased number of trips, if the asteroid has not been fully depleted. Similarly, a further sensitivity analysis demonstrates that by changing the destination orbit for the processed resources to the Lunar Gateway, increased profit margins can be realised