Sprint 4: Earth-Mars Architectures with ISRU
Assumptions
To frame this sprint, we operated on the assumption that the primary mission objective of a planned manned Mars mission is to establish a presence for human habitation, driven primarily by crew safety and scientific value.
Qualitative research into the feasibility of different mission designs and quantitative assessment of component trades identified some aspects of a Mars mission that were dominant over other alternative options. In these cases, we made assumptions to use what we found to be the dominant option and did not trade on that component, as using an alternative option would produce an end architecture that was either infeasible or strictly dominated in terms of cost, exploration capability, and risk. These assumptions include:
- Conducting a 500 day conjunction class mission. While opposition missions reduce the amount of time a crew spends in transit (and limits their risk and radiation exposure), they require a large amount of energy and provide a very short (30-90 day) stay on the surface of Mars. A 30-90 day stay would likely significantly limit the ability of a crew to establish a permanent presence and conduct necessary science and ISRU activities.
- The trajectory is set due to the choice of a conjunction class mission.
- The spacecraft with use CH4 fuel. This was previously shown to be the superior option.
- A manned presence will be established at a single location, and short trips for scientific and exploration purposes will be taken based around that location. Different approaches will be considered in future sprints.
- The mission will use ISRU (atmospheric).
- The only profit incentive at this time for commercial companies is through contract work on NASA services and components. Commercial feasibility was discussed in a conversation with NASA economist Dr. Robert Shishko.
Morph Matrix
| Decision | A | B | C | D | E |
|---|---|---|---|---|---|
| Rover | MSC | Mars Direct | DRM 1 | Mobile Home | Commuter |
| EDL | Retropropulsion | Supersonic Decelerators | Hypersonic Aeroassist | Deployable Entry System | |
| Landing Location | Jezero Crater | Midway | Northeast Syrtis | Columbia Hills | |
| Crew Size | 2 | 3 | 4 | 5 | 6 |
Metrics
Rover
We leaned on archived NASA studies to obtain cost data, mass and crew sizes to complete the table below for several DRMs. Given that this information is not readily available, we engaged in several discussions with NASA personnel, who archive Mars studies at NASA HQ for data access. Sse_studentx (talk) 21:11, 9 April 2019 (UTC)
Rank was determined qualitatively, based on which scenarios would provide a good baseline for comparison (Apollo), which NASA sees as the most promising (DRM 5.0), and the highest TRL (Space Exploration Vehicle).
- NASA Manned Planetary Missions Requirements Group (PMRG) -- Manned Spacecraft Center (MSC) (1971)
- Minimal support from White House (Nixon) for Mars mission, so MSC aimed to have an austere mission that would maximize likelihood of getting support
- Tandem convoy mitigates "walk back" limitation on distance traveled and improves exploration area from 80 square miles for one rover to 8,000 square miles for two rovers
- Martin Marietta Mars Direct (1990)
- Robert Zubrin's plan; single rover with comparatively high cost
- NASA Reference Design Mission (DRM 1.0) (1993)
- Adapted from Mars Direct (nicknamed 'Mars Semi-Direct') but expanded crew size
- Utilizes tandem convoy architecture
- NASA DRM 5.0 (2009) - "Mobile Home" Scenario
- Assumes a primarily mobile operation where crew spends significant periods (up to 2-4 weeks) away from landing site
- Tandem convoy concept with two rovers that are each capable of housing full crew in case one rover fails
- NASA DRM 5.0 (2009) - "Commuter" Scenario
- Assumes a stationary habitat with short trips in rovers
- Plan includes two pressurized and two unpressurized rovers (unpressurized rover ~= Apollo Lunar Exploration Vehicle)
- Apollo Lunar Exploration Vehicle
- Good baseline for analysis; uses unpressurized rover for exploration
- NASA Space Exploration Vehicle
- Existing technology --> highest TRL of all the enumerated options
- Upgraded Apollo Rover
- Idea that the Apollo rover would be much more capable if built today with advances in materials and technology
- Upgraded, Extended Apollo Rover
- Based on the upgraded Apollo Rover, but for an extended crew (4 instead of 2)
- Extended Space Exploration Vehicle
- Based on SEV, but for an extended crew (4 instead of 2)
| Rank | Rover | Mass (kg) | Crew Capacity | Capacity (mT) | Max Range (km) | Pressurized? | Cost | Notes |
|---|---|---|---|---|---|---|---|---|
| Medium | MSC PRMG Rovers | 185 | 1 (per each of two vehicles) | 11.7 | 160 | No | $16B Design + manufacturing | Part of "tandem convoy": would send one astronaut in each of two rovers, mitigating "walk back" limit. |
| Low | Mars Direct Rover | 1400 | 4 (assumed based on mission) | 26.9 | 500-1000 | Yes | $44B Design + manufacturing | Range limited by walking capacity of astronauts |
| Medium | DRM 1.0 (1993) | 1290 | 2 (per each of two vehicles) | 19.4 | 500 | Yes | $36B Design + manufacturing | |
| High | DRM 5.0 (2009) - "Mobile Home" Scenario | 5562 | 3 in nominal operations, 6 in emergency (per each of two vehicles) | 31.9 | 300 | Yes | $21B Design + manufacturing | Part of "tandem convoy"; allows docking between vehicles |
| High | DRM 5.0 (2009) - "Commuter" Scenario | 500 | 2 (per each of two vehicles) | 16.3 | 100 | No | $18B | |
| High | Apollo Rover | 210 | 2 | 0.49 | 7.6 | No | Manufacturing | Range limited by walking capacity of astronauts |
| High | NASA Space Exploration Vehicle | 2994 | 2 | 1 | 201 | Yes | Manufacturing | <-- Re: exploration capability: I believe the value should be much higher for pressurized rovers |
| Low | Upgraded Apollo Rover | 157.5 | 2 | 0.49 | 7.6 | No | Manufacturing | Based on a study that shows that cars had an average reduction in weight of 25% from the beginning of the 1970's due to upgraded technology and materials: http://faculty.washington.edu/dwhm/wp-content/uploads/2016/02/authorFinalVersion.pdf |
| Low | Upgraded, extended Apollo Rover | 189 | 4 | 0.49 | 7.6 | No | Design + manufacturing | Based on mass percentage of vehicles that is for passengers |
| Medium | Extended Space Exploration Vehicle | 3900 | 4 | 1100 | 201 | Yes | Design + manufacturing | Based on scaled up passenger cabin. |
Crew Surface Duration (Trajectory)
Past Marsian mission architectures have favored a conjunction trajectory over an opposition trajectory given its longer on-surface or in-Marsian-orbit duration. The longer duration time corresponds to higher exploration capacity on Mars. Examples include the Mars Direct Architecture and DRM 5.0. However, work by Bryan Mattfeld et al, in Trades Between Opposition and Conjunction Class Trajectories for Early Human Missions to Mars indicates a different trade between the two trajectories based on risk instead of explorational potential. They argue that despite the higher energy requirement for an opposition trajectory, it offers benefits on overall risk reduction and higher system performances, which could be more suitable for an initial, short-term Mars Mission.
For this sprint, the team has decided on a Conjunction trajectory with crew surface duration of around 550 Earth days. Further trade on the Conjunction and Opposition trajectories with different FOM will likely be included in the next sprint.
| Rank | Surface Duration Options on Mars | Corresponding architecture | Total Mission Time (Human Duration Beyond LEO) | Crew Capacity per Mission | Total DeltaV (km/s) | Mars Parking Orbit | SEP Aggregation Point | Habitable Volumn & Total Pressured Volumn | Dry Mass Total | Inert Mass Subtotal | Total Propellent Wet Mass | Risks (Trades on Mission Reliablity) | Human Exposure to Deep SpaceRadiation | Radiation Harzard Amount | Purpose on Surface | Landing Site Criteria | Exploration Aera | Infrastructure requirement | Note | Reference |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Low | 20 days | Mars Direct (Opposition Class Option) | 500 Days | NA | NA | NA | NA | NA | NA | NA | NA | Spacecraft Systems Risk; Propulsion Systems Risk;Crew Autonomy Risk; Crew Health Risks (non radiation related) ; Radiation Risk ;Spacecraft Launch and Aggregation; Earth Return and Re-Entry; | Maximum 500 Days (adjusted for protection at moons or on surface) | 44.8-71.8 rem | http://www.marspapers.org/paper/Zubrin_1991.pdf ; https://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/20150001240.pdf | |||||
| Medium | 40 days | NASA Tradestudy for Early Mission to Mars (Opposition Class) | 560 Days (-445 compared to Conjunction) | 4 | 5.69 (+105% compared to Conjunction) | 250 km x 7,660 km | SEP Aggregation Point | 78.3 m^3 & 161.5 m^3 | 17871 kg | 27144 kg (less consumables and spares mass requirement compared to Conjunction = 20% vs 31%) | 86.5 tons | Overall smaller than Conjunction with exception: Spacecraft Systems Risk (-); Propulsion Systems Risk (-);Crew Autonomy Risk (-); Crew Health Risks (non radiation related) (-) ;Radiation Risk (-);Spacecraft Launch and Aggregation (+); Earth Return and Re-Entry (+); | Maximum 560 Days(adjusted for protectionat moons or on surface) | NA | Explorational and scientific, but less intensive. | NA but More Flexible | NA but less | No need of SHAB? | The study suggests Opposition for initial Mars Mission bc despite its larger total energy requirements relative to conjunction-class missions, it offers the potential for much shorter mission durations, potentially reducing risk and overall systems performance requirements. Deeper analysis reveals Opposition trajectories will always require greater propulsive loads than conjunction trajectories; however, the relative impact can be mitigated slightly through lower loaded element masses and optimized DeltaV mission splits. | https://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/20150001240.pdf |
| High | 558 Days | DRA 5.0 (Conjunction Class); NASA Tradestudy for Early Mission to Mars (Opposition Class) | 1005 Days | 4 | 2.81 | 1-Sol Elliptical | SEP Aggregation Point | 78.3 m^3 & 204.9 m^3 (+21% Compared to Opposition) | 19969 kg (+25% compared to Opposition) | 36200 kg | 267.9 tons | Spacecraft Systems Risk (+); Propulsion Systems Risk (+);Crew Autonomy Risk; Crew Health Risks (non radiation related) ; Radiation Risk (+) ;Spacecraft Launch and Aggregation (-); Earth Return and Re-Entry (-); Extreme Marsian Weather (Dust Storm) (+) | Maximum 1005 Days(adjusted for protectionat moons or on surface) | 41.3-61.4 rem | primary science (extraterrestrial life) and exploration activities | broad, flat with scientific interest; a zone of minimum biological risk (temperature) | Rover + Crew: 100 km total distance before re-supply | descent/ascent vehicle (DAV); surface habitat (SHAB) | In DRA 5.0, the sensitivity of propellant load to trajectory led to the conclusion that opposition-class missions would be difficult to execute with current propulsion technologies. | DRA 5.0; https://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/20150001240.pdf |
| High | 550 Days | Mars Direct (Conjunction Class) | 949 Days | 4 or 12 depending on rocket type | 2.81 | 1-Sol Elliptical | SEP Aggregation Point | NA | NA | NA | NA | Spacecraft Systems Risk (+); Propulsion Systems Risk (+);Crew Autonomy Risk; Crew Health Risks (non radiation related) ; Radiation Risk (+) ;Spacecraft Launch and Aggregation (-); Earth Return and Re-Entry (-); Extreme Marsian Weather (Dust Storm) (+) | Maximum 949 Days (adjusted for protection at moons or on surface) | 41.3-61.4 rem (*see attached image) | of scientific interest and at low elevation in prevention of radiation | Rover: 22,000 ground kilometers (up to 500 km out from the base) ; Rover + Crew:800,000 square kilometers | 1 fully-fueled ERV, fueled by nuclear reactors on rover (11 tonnes ofmethane/oxygen bipropellant allocated for surfaceoperations); 1 ERV for habitat module | http://www.marspapers.org/paper/Zubrin_1991.pdf |
Lydzhang (talk) 23:55, 9 April 2019 (UTC)
Entry, Decent and Landing
| Ranking | Payload (mT) | Landing Ellipse (m) | Cost (Million) | Initial Mass (mT) | Safety Ranking (Lowest is safest) | Landing Site Criteria | Reusable | Weather | Risk (weather, human factor) | Notes | Reference Mission | |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Retropropulsion with no aerocapture | 2 | 265 | <100 | ~100 | 280 | 2 | None | Yes | None | Low | LOX / Liquid Methane | Mars Direct |
| Supersonioc decelerators (parachutes and retrorockets) | 4 | 84 | <5000 | ~20 | 86 | 3 | 0 km MOLA | No | Avoid Dust Storm Season | High | Current Robotics Mars Missions | |
| Hypersonic Aeroassist Entry System | 1 | 40.4 | <100 | ~100 | 110.2 | 1 | None | Yes | None | Medium | DRM 5.0 | |
| Deployable Systems | 3 | 107 | <1000 | ~50 | 115 | 4 | Low altitude region | No | Avoid High Winds | High | Possibility to Reduce Mass by 20% |
Considerations
Retropropulsion only
- Requires ISRU on surface
Parachutes and retrorockets
- Used by Viking landers
Parachutes, retro-rockets and airbags
- Used by Mars Pathfinder and Mars Exploration Rovers
- Can only be used for masses <200 kg
Parachutes and rocket-powered sky crane
- Used by Curiosity and Mars 2020
- Allows for immediate deployment and no propulsion on the payload
- Possibly to scale, yet restricted by use of tethers to lower the payload to the surface
Penetrators
- A protective outer shell breaks away and absorbs force of impact
- Can only be used on non-delicate spacecraft
Hypersonic Inflatable Aerodynamic Decelerators and Deployable Entry Systems
- Never proven and difficult to design
Habitat Architectures
| Habitat Typologies | Initial Mass (kg) | Crew Capacity | Cost (USD) | Payload Capacity (kg) | Duration (days) | Range (km) | Habitable Volume (m^3) | Radiation Protection | Notes |
|---|---|---|---|---|---|---|---|---|---|
| Mars Transit Habitat (Langley + MSFC) | 28100 (w/o consumables) 41340 (w/ consumables) | 4 | 1542 | 40 | 200 | 65.8 | no GCR and SPE protection beyond onboard logistics placement and layout options | ||
| Mars Excursion Module (Ascent/Descent Vehicle) | 49400 | 4 | 3.1 - 5B | 2700 | 30 | 4 | The design was modular, so that by deleting ascent propellant and internal compartments and surface supplies, total lander mass could be between 30.0 and 49.4 metric tons. The lighter stripped lander, departing from and returning to a low-earth orbit Mars orbiter, could support only two crew for four days on the surface. The heavier all-up version could support four crew for thirty days and had enough delta-V to reach an orbiter in a higher Mars elliptical orbit. Variations of internal equipment fit and propellant between these extremes could accommodate a variety of missions. http://www.astronautix.com/m/mem.html | ||
| ATHLETE (JPL All-Terrain Hex-Limbed Extra-Terrestrial Explorer) | 850 | n/a | 450 | n/a | n/a | n/a | |||
| Ice Home Mars Habitat (Langley + SEArch) | 18000 | 4 | n/a | n/a | n/a | 13.3 | Using the Mars Ice Home design with the vertical slice water cell configuration about 655 m3 of water was required to provide a shielding value that reduced the effective dose to 50% of an unshielded crew member. It should be noted that a habitat consisting of an aluminum shell will actually increase effective dose through the generation of secondary particles so using an unshielded crewmember is a conservative assumption. 655 m3 at a production rate of 0.5 m3/day would take 1310 days to completely fill. At this point in time, given the challenges of water extraction, the shield thickness is believed to be as thick as practical. A primary tenant for radiation protection is to make the effective dose As Low As Reasonably Achievable (ALARA) | ||
| Rover for Advanced Mars Applications RAMA (ESA + Thales Alenia) | 6300 (w/o consumables) 8300 (w/ consumables) | 3-4 | n/a | 40 | n/a | 54 | ALARA (As Low As Reasonably Achievable)Hull Integrated ShieldingExternal Regolith ShieldingWater Shielding | http://adsabs.harvard.edu/abs/2010cosp...38..437I | |
| Argo Dual-Purpose Habitat Module | 4-6 | n/a | 500 | n/a | 63 | 2 cm thick Aluminum(Al)-Polyethylene(PE)-Aluminum(Al)-shieldAstrorad radiation vests | The habitat rotates around its center at 6 rpm in order to generate 0.38 g artificial gravity. | ||
| DRM 1 Pressurized Mars Rover (Hoffman & Kaplan) | 16500 | 2-4 | n/a | 20 | 500 | 6.9 | |||
| DRA 5.0 Surface Systems "Commuter" Scenario | 40400 (Habitat Lander) 18430 (DAV Lander) | 2 | n/a | 100 | n/a | 197.7 | This scenario included a centrally located, monolithic habitat, two small pressurized rovers, and two unpressurized rovers (roughly equivalent to the Apollo LRV). | ||
| DRA 5.0 Evolvable Mars Campaign Monolithic Outpost | 42058 | 4 | n/a | 500 | n/a | 183.7 | |||
| DRA 5.0 Evolvable Mars Campaign Vertical Modular Outpost | 47296 | 4 | n/a | 500 | n/a | 211.2 | |||
| DRA 5.0 Evolvable Mars Campaign SLS/EUC-Derived Propellant Tank Outpost | 51143 | 4 | n/a | 500 | n/a | 353 | |||
| DRA 5.0 Evolvable Mars Campaign Small-Diameter Modular Horizontal Outpost | 49469 | 4 | n/a | 500 | n/a | 200.5 | |||
| Ascent/Descent Vehicle Cabin (JSC MMSEV) | 4 | 250 | 5 | n/a | 13.3 | This scenario included a centrally located, monolithic habitat, two small pressurized rovers, and two unpressurized rovers (roughly equivalent to the Apollo LRV). | |||
| Pressurized Rover (JSC MMSEV) | 3000 (w/o chariot) 4000 (w/ chariot) | 4 | 152.9M | 1000 (w/o chariot) 4000 (w/ chariot) | 30 | 125 | 10.8 | water and polyethylene shield |
Sortie Type
Sortie Type refers to the combination of launches required to support the Mars mission. For example, all crew and cargo could be transported in a single, huge transit vehicle with a necessarily powerful launch vehicle, or cargo could be delivered ahead of time to reduce the mass of the crew launch, thereby increasing margin for delta v to reduce transit time and opening up mass budget for life support systems.
To build our morph matrix, we analyzed three sortie cases: A Mars Direct scheme championed by Robert Zubrin, a Mars Cycler program publicized by Buzz Aldrin, and NASA's 2009 Mars DRA 5.0. Research into NASA's 2015 Journey to Mars Pathway and the Evolvable Mars Campaign found many details for architectural components and necessary technologies, but work looking into overall architectures and transportation logistics was found to be underdeveloped for our purposes. Additionally, the Evolvable Mars Campaign involved first pre-deploying equipment and then sending a crew to Phobos, which we determined is out of this sprint's scope since we are focused on getting humans to the surface of Mars as quickly and safely as possible.
Below is a table with a break-down of the projected number of sorties, number of launches, total duration, mass, and cost of the three transportation architectures (Mars Direct, Mars Cycler, and NASA DRA 5.0)
| # Sorties (Launch Sets) | # Launches | Total Duration | Mass | Cost | |
|---|---|---|---|---|---|
| Mars Direct | 1st Sortie: Earth Return Vehicle (ERV) Launch
2nd Sortie: 2nd ERV and Habitat Module |
1st Sortie: 1
2nd Sortie: 1+
|
1st Sortie: 6 months for travel (13 month after landing to be fully fueled)
2nd Sortie: Launched 26 months after 1st ERV Launch, 8 months for travel (1st Mission given 18 months on surface, 6 months to travel back) Total Transport Duration: 34 months Total Mission Duration: 58 months |
121 t into a 300 km circular orbit Boost 47 t toward Mars | $450B spread over 20 to 30 years |
| Mars Cycler | 1st Sortie: Establish Aldrin Cycler on trajectory
2nd Sortie: Payload/Crew Vehicle(s) |
1+ for Each Sortie - Aldrin Cycler (May require several vehicles) and
Payload/Crew Vehicle(s) Total: 2+ (Min) |
Cycler Trajectory: Earth to Mars in 146 days -->
Next 16 months beyond Mars orbit --> Another 146 days from Mars to Earth Total Mission Duration: 780 days |
1999 NASA study estimated IMLEO: 437 t (250 t propellant) | Unknown |
| NASA DRA 5.0 | 1st Sortie: Cargo Launches (Surface Habitat and Descent/Ascent Vehicle) w/ LEO rendezvous
2nd Sortie: Cargo + Crew Launches that rendezvous in LMO for surface descent |
1st Sortie: 4 Ares-V Cargo Launches
2nd Sortie: 1 Ares-I Crew Launch, 3 Ares-V Cargo Launches Total: 8 |
1st Sortie: 350 Days to Mars
2nd Sortie: Launched 26 months after 1st Sortie, 200 Days to Mars, 500 Days at Mars, 200 Days to Earth Total Mission Duration: 56 months |
Descent/Ascent Vehicle: 63.7 t
Lander + Mars entry Aeroshell: 106.6 t Surface Habitat: 64.2 t Surface Habitat + Aeroshell: 107 t Transit Habitat Mass: 41.3 t Orion: 10 t Total Payload Mass: 264.9 t Ares V Capability: 125 t + to LEO In-Space Transport Capability: 110-125 t to Trans-Mars Injection |
Unspecified |
Considerations:
- Mars Direct:Redundacy is built into the architecture. 2nd ERV can still make it back if the 1st vehicle fails. If ERV works as planned, can land the second ERV in a different location to expand exploration capability
- Mars Cycler:Cycler is able to recycle water and air, has shielding, and contains everything for a trip that would take months. Large and heavy to sustain crew. However, the Payload/Crew Vehicle needs to accelerate to rendezvous, then decelerate after splitting with the Cycler. Calculations predict the Cycler to be traveling at a velocity of 10 km/s around Mars. However, Payload/Crew Vehicle should be much smaller and cost would be much smaller than accelerating the whole Cycler every time
- NASA DRA 5.0:Pre-deployment enables system checkout and operations (e.g. ISRU and robotic exploration) prior to crew departure from Earth, many smaller launches and assembly in space allows for larger cargo/craft to be sent without significant cost/technological burden
Exploration Capability
There are four landing sites being considered; Columbia Hills, Jezero crater, Midway, and Northeast Syrtis. These are illustrated in the map below. No locations appear to have significant water ice (as measured by ‘water equivalent hydrogen’ proximity.), but have significant ISRU capability within a 500km radius of the landing location.
Exploration capability is determined by a weighted measure of distance between landing location and substantial (>10%) WEHA, as well as a "scientific potential" capability that is a combination of in-situ science, returnable cache science, confidence in scientific novelty, and relative diversity of geology near the landing site.
| Landing Site Exploration Ranking | Potential Landing Site | Distance from Water for ISRU | Distance to Other Geologic Regions |
|---|---|---|---|
| High | Columbia Hills | 138km | 50km |
| Medium | Jezero Crater | 450km | 130km |
| Medium | Midway | 450km | 150km |
| Low | Northeast Syrtis | 450km | 200km |
Business Considerations
File:Business Considerations 2.png
Plots
See jupyter notebook: [1]
Future Considerations for Sprint 5 (Earth-Moon-Mars)
- What is our overall mission objective?
- What are our requirements? What are our priorities?
- What activities will be performed on the Moon/Mars? (ISRU, Settlement, Science, Exploration, Testing, etc.)
- What will be the architectures on the Moon and Mars surface? (Single-site, Multi-site, transportation)
- How soon do we want to get to the Moon and Mars?
- How long do we want to stay on the Moon/Mars?
- What are our assumptions?
- How will we get to the Moon/Mars?
- How does adding the Moon/Mars change our trajectories?
- Should we consider other nodes? (EMLs, Phobos, Deimos, etc.)?
- What new propulsion technologies are feasible/needed?
- How much similarity do we want/can we have between the Moon and Mars?
- How can we reuse research that we have already done?
- What technologies can be used for both the Moon and Mars?
- What additional technological developments should we consider?
- What infrastructure do we absolutely need?
- How much reusability do we hope to/can we achieve?
- How can we involve the commercial and governmental interests from Sprint 3?
- What are our constraints?
- What value can we add to research that has already been done?