TransAstra Corporation recently completed an in-depth study of how to use resources from near Earth objects to facilitate space exploration and settlement.
The 82-page report, “Stepping Stones: Economic Analysis of Space Transportation Supplied From NEO Resources,” was funded with a $100,000 grant from NASA’s Innovative Advanced Concepts (NIAC) program.
“The Stepping Stones economic analysis of space transportation supplied from near-Earth object (NEO) resources demonstrates the potential to break the tyranny of increasing space transportation costs created by dependence on Earth-based resources, particularly propellant,” the report states.
“By using Asteroid-Provided In-Situ Supplies (Apis™) spacecraft to extract resources from NEOs and the creation of a space-based transportation infrastructure, including a crewed lunar outpost in an energetically advantageous lunar orbit for storage and propellant processing along with reusable spacecraft for transport, these resources can be utilized to support crewed lunar surface exploration, crewed NEO exploration, crewed Mars missions, and even space tourism at less than 25% of the cost otherwise required (~90B$ vs ~390B$ over 20+ years),” the report adds. “This analysis further suggests that with relatively modest initial government investment, a business case can be developed for a profitable industry in space resources.”
I’ve reproduced the abstract, executive summary and an overview of four mission scenarios below. You also can download the full report here.
Stepping Stones: Economic Analysis of Space Transportation Supplied
From NEO Resources
Final Report on Grant No NNX16AH11G Funded Under Economic
Research for Space Development
Technical Officer: Lynn D. Harper PhD
PI: Joel C. Sercel, PhD
The Stepping Stones economic analysis of space transportation supplied from near-Earth object (NEO) resources demonstrates the potential to break the tyranny of increasing space transportation costs created by dependence on Earth-based resources, particularly propellant. The increasing challenges of space exploration, particularly by humans, rapidly become unaffordable if only Earth based resources are available. By using Asteroid-Provided In-Situ Supplies (Apis™) spacecraft to extract resources from NEOs and the creation of a space-based transportation infrastructure, including a crewed lunar outpost in an energetically advantageous lunar orbit for storage and propellant processing along with reusable spacecraft for transport, these resources can be utilized to support crewed lunar surface exploration, crewed NEO exploration, crewed Mars missions, and even space tourism at less than 25% of the cost otherwise required (~90B$ vs ~390B$ over 20+ years). This analysis further suggests that with relatively modest initial government investment, a business case can be developed for a profitable industry in space resources.
1.0 Executive Summary
NASA faces many challenges, both technical and programmatic, in its human exploration program. The commercialization and colonization of space faces similar challenges. Of all these challenges, perhaps the most daunting is the cost of missions. Cost is currently driven by launch and in-space transportation costs. Energetically difficult missions require either massive launch vehicles or multiple launches, as they require a great deal of propellant to achieve their missions. This makes these missions very expensive, which means they must be over-engineered for success, which drives up the cost of development, which reduces the frequency of missions, which eliminates the possibility of any economies of scale in missions.
Unless an approach is found to break this cycle of increasing costs, human exploration, commercialization, and colonization of space will likely remain unaffordable. This report details an approach based on use of in situ asteroid resources along with novel technology for extracting and using these resources. Combined with a spacecraft design and mission architecture this approach has the potential to break the spiral of increasing costs and provide not only an affordable path of human exploration, but the possibility of a self-sustaining business of space resource utilization.
Near Earth Asteroids (NEOs) are more energetically accessible than the surface of Moon. This makes them potential “Stepping Stones” of resources for propellant and other consumables required for missions. This report demonstrates how the Asteroid Provided In-Situ Supplies (Sercel 2016) (Apis™) spacecraft architecture, which includes a new approach to asteroid in situ resource utilization (ISRU) called “Optical Mining™” (Sercel 2015) can capture and extract resources from NEOs. This architecture builds off of previous study and laboratory work, both in terms of NEO characterization, technology for capture of small asteroids (such as the Asteroid Redirect Mission Study), and new technology development for ISRU.
This study performs a benefit analysis of applying this approach to using NEO resources for NASA crewed exploration missions over the next 20+ years based on a notional but reasonable roadmap of missions used to calculate and compare costs of this new approach to estimates of current costs. The goal of the study is to create a self-sustaining, reusable, robotic or crewed space transportation approach using Apis™ architecture spacecraft, along with other key elements, such as a manned
propellant depot in an energetically useful orbit around or near the moon equipped with propellant processing capability, and a reusable spacecraft that can serve as both an orbital transfer vehicle and an ascent/descent vehicle.
All these elements were combined to support evaluation of a roadmap of mission scenarios for development and operation of the lunar orbiting outpost and fuel depot, multiple NEO exploration missions, sustained lunar surface exploration and operation missions, and Mars exploration missions, performed over an approximately 20 year period. This evaluation supported estimation of initial design, development, test, and evaluation (DDT&E) costs, recurring unit costs, replacements costs, and launch costs for these scenarios using high level cost-modeling techniques applicable to concept level studies. Cost estimates were made for comparison of four development and operation variations of the scenarios in the roadmap:
- NASA Business as Usual supplied from Earth (no ISRU)
- Commercial Best Practices supplied from Earth (no ISRU)
- NASA Business as Usual with Asteroid Resources (ISRU)
- Commercial Best Practices with Asteroid Resources (ISRU)
Commercial Business Practices approaches, such as those pioneered by Space X and Blue Origin have demonstrated their ability to produce space vehicles at a fraction of the costs traditionally associated with NASA development. Even assuming comparable savings, without the use of asteroid resources, the results show the total cost of exploration of space will remain unaffordable.
As Table 1-1 shows, use of asteroid resources, combined with best commercial business practices, succeeds in reducing the costs by more than a factor of 4 for a robust plan of human exploration of the lunar surface, NEOs, and eventually the surface of Mars. Assuming a reasonable investment by NASA in the initial DDT&E for the elements of this architecture and commitment to use the capability provided at a reasonable price, along with the ability to obtain adequate initial start-up capital, this approach does so in a fashion that can create a self-sustaining business in space resources that achieves an estimated profit of >20% annually before the end of 20 years. (See Figure 1-1.)
This business can be further expanded and made even more profitable through development and fielding of more advanced designs of key elements over time. This further reduces the cost of asteroid resources and provides increased commercial support to a burgeoning space tourism business and even enables cost effective development of various sized (100s to 1000s of inhabitants) space habitats and the eventual colonization of space.
5.0 Overview of Mission Scenarios
5.1 Mission Scenarios Considered
Four sets of NASA crewed missions were developed for use as mission scenarios. These include:
- Establishment and maintenance of Lunar Orbital Outpost, established in Lunar Distant Retrograde Orbit (LDRO) and operated for life of scenario.
- Near Earth Object (NEO) Exploration focused on crewed missions to a variety of small (10 m class) targets. These consist of five missions of approximately 14 months duration.
- Lunar Surface Operations (LSO) including establishment and operation of a lunar surface base based on two crewed and two cargo landings per year.
- Mars Exploration, initially four crewed exploration mission to Deimos with a crewed Mars landing and return but reduced to 3 for the final cost analysis when the timeline is extended to 20 years. Return missions could lead to the establishment of a Deimos or Mars surface base, but are not covered in the version of this scenario presented.
Additionally, a scenario applying this architecture to LEO to GEO commercial satellite transportation based on current projections of the market is included.
Figure 5-1 shows an integrated roadmap of all of the above mission scenarios. Mars and some NEO missions are staged out of LEO in the Non-ISRU case. All ISRU missions are staged out of LDRO from Honey Bee supplies once the Lunar Outpost is established. Those Non-ISRU missions staged out of LDRO require additional propellant brought to LDRO from Earth.
Figure 5-2 shows the typical ΔVs for transition between relevant orbits and destinations. Worker Bees (all H2O) or Reusable Spaceships (all LOX-LM) pick up payloads in LEO and deliver them to the LDRO Outpost in Apis transportation cases as illustrated in Figure 5-3. One exception is in transferring commercial satellites from LEO to GEO orbits. The Worker Bees or Reusable Spaceships then return from GEO to the Outpost for refueling.
Apis options evaluated include both Worker Bee and Reusable Spaceship options for each scenario. Also included are assumptions regarding the 14 month Honey Bee 100 ton water return missions launched or operated prior to each scenario need for propellant. The original scenario definition covers 10 years which is then expanded to consider the 20 year integrated scenario.
5.2 Key System Elements Included In Mission Scenarios
As mentioned briefly before and described in more detail in section 6, the key system elements applied in this study to the mission scenarios are:
- Honey Bee, the Apis mining vehicles with propulsion, raw ISRU product storage, and Optical Mining™ components for NEO resource harvest and transport
- Two Worker Bee variants for cargo transport
– A separable 2 spacecraft version with aeroshells for Earth aerocapture/braking
– A single spacecraft without aeroshells for other deep space missions (NEO, Mars)
- Lunar Orbital Outposts as transportation node and propellant depots
- “Fontus” consumable and propellant production systems at key locations (Lunar Outpost and Deimos) for propellant processing consisting of:
– An electrolyzer for H2/O2 separation,
– A Sabatier system for LM/LOX production,
– Cryogenics for LM/LOX/LH2 production, and
– Tanks for storage (and support spar)
- Scooter enhanced microgravity EVA systems at key nodes, and
- Crewed Deep Space Exploration System (DSES) for NEO and Mars exploration.
5.3 Vehicle Mass Modeling
Wherever possible, actual flight hardware has been used in developing mass models. As improvements in some areas are expected, this should create a conservative baseline for most subsystems. Conservative estimates and generous margins have been applied to all new technology, in particular:
- Inflatable systems for Apis spacecraft,
- Optical Mining™ apparatus (aka Stinger),
- Solar Thermal Propulsion (Sercel Omnivore™ engine), and
- Asteroid capture system (from JPL initial design and analysis).
The mass models were supported by best available technical estimates and published literature where possible and subject to multiple review.
Some assumptions had to be made regarding the aeroshells for the Worker Bee Earth-aerocapture/braking system. Initially, 15% of entry mass as recommended by Palaszewski (NASA Technical Paper 3065 – Lunar Missions Using Chemical Propulsion: System Design Issues) is considered for single pass aerocapture. However, actual aeroshell mass can fall to near zero based on trade against the time taken to achieve desired orbit through multiple passes through the atmosphere. Campbell, Argrow and Ralph in “Aerobraking in the Cis-Lunar Economy” (AIAA 2017-0468) present data that multiple passes can be easily used to achieve LEO in less than 3 weeks without an aeroshell – experiencing only small heat loads. Both the Magellan and Mars Global Surveyor spacecrafts used aero-braking without any additional shielding to modify their orbits. As a compromise,15% is used for aerocapture/braking protection on the dry mass spacecraft portion attached to the main water tank, with only 2% used for the water tank aeroshell. This approach can benefit from additional study and analysis and will likely result in some level of further mass reduction.
The Worker Bee reflector with the STR spacecraft portion makes a separate propulsive maneuver to rendezvous using a small separate water propellant tank. All subsystems necessary for maneuvering and rendezvous are duplicated on both spacecraft portions. The Worker Bee main tank is sized for the maximum propellant load anticipated in mission scenarios.”
There are some additional assumptions on the ΔV’s used for the Apis versions of the scenarios. All Apis spacecraft (Honey Bee and Worker Bee) have Omnivore Solar Thermal Propulsion engines (Omnivore™) sized to be capable of 100 newton thrust levels with an Isp of 335 seconds. In addition, Honey Bee missions are launched from Earth on a direct injection trajectory to interplanetary asteroid resource trajectories on their first missions. All subsequent missions are staged out of the Lunar Outpost in LDRO. All mission departures and returns (NEO exploration and Mars Exploration) are from/to the Lunar Orbital Outpost which require a much lower ΔV than the outbound ΔV from LEO used for the Non-ISRU cases. It is also worth noting that the primary difference in performance between Worker Bees and Reusable Spaceships is the lighter weight of the Worker Bee versus the higher efficiency of the Reusable Spaceship LOX/LM engines based on using high expansion nozzles. This results in slight net launch mass savings for the Worker Bee option, but it is small enough to probably be within the uncertainty bounds of the study.