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Earth-Mars Artificial-G NEP Architecture Sun-Earth L2 Architecture 3-Week Parametric Trade Study

Earth-Mars Artificial-G NEP Architecture Sun-Earth L2 Architecture 3-Week Parametric Trade Study Presented to JSC/Exploration Office March 3, 2003 Low Thrust Trajectory Team – GRC, JPL, JSC, MSFC Presentation prepared by: Jerry Condon / JSC / EG5 / 281.483.8173 / gerald.l.condon@nasa.gov.

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Earth-Mars Artificial-G NEP Architecture Sun-Earth L2 Architecture 3-Week Parametric Trade Study

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  1. Earth-Mars Artificial-G NEP Architecture Sun-Earth L2 Architecture 3-Week Parametric Trade Study Presented to JSC/Exploration Office March 3, 2003 Low Thrust Trajectory Team – GRC, JPL, JSC, MSFC Presentation prepared by: Jerry Condon / JSC / EG5 / 281.483.8173 / gerald.l.condon@nasa.gov Preliminary

  2. Inter-center Study Team • GRC • Melissa McGuire, Rob Falk • JPL • Jon Sims, Greg Whiffen • JSC • Jerry Condon, Ellen Braden, Dave Lee, Kyle Brewer, Carlos Westhelle • Jim Geffre • MSFC • Reginald Alexander, Larry Kos, Kirk Sorensen

  3. 3- Week Study • 2 Studies – NEP parametric mission design trades Study 1 - Round trip Earth/Mars mission • Augment results from NEP (EM-L1 departure) study done last year at JSC • Determine cost (mass, time) to depart from Earth orbit and spiral to/from selected Mars parking orbits for Earth return Study 2 - Sun-Earth libration point (L2) mission • Deploy/maintenance of satellite constellation • Dress rehearsal for Mars mission • Due date – March 3, 2003 • Customers • JSC/ExPO – Kent Joosten, Bret Drake, Brenda Ward, etc. • HQ/Gary Martin

  4. Contents • Study 1 - Round Trip Earth/Mars Mission • Study 2 - Sun-Earth L2 Libration Point Mission • Appendix • Mars Arrival Parking Orbit Analysis • Mars Parking Orbit Lifetime • Integrated Reference Mission • Effects of Parking Orbit Geometry on Mars Lander Mass • Trapped Proton Belt Data

  5. Study 1Round Trip Earth/Mars Mission

  6. Round Trip Earth/Mars Mission Assumptions • Two vehicles • NEP Mars Transfer Vehicle (MTV) • Object of parametric study • Lander/Ascent Vehicle (LAV) • Previously deployed at Mars • Use same vehicle specifications as last year (2002) study for Artificial Gravity Mars transfer vehicle*: • Power = 6 MW, Engine efficiency = 60%, Isp = 4000 sec, Tankage fraction = 5% • Final mass target (back at Earth) = 89mt • No thrust vector turning constraints • Determine vehicle thrust vector steering requirements unconstrained by Artificial Gravity (AG) vehicle configurations • Results may influence AG vehicle configurations • 2026 opportunity, <90 day stay in Mars vicinity >30 days surface stay • Initial Earth orbit 700 km circular LEO • Crew taxi transfers crew from ground to crew transfer altitude (30,000 – 90,000 km) • No constraint on heliocentric closest approach to Sun Fire Baton Artificial-G NEP Mars Transfer Vehicle * Preliminary Assessment of Artificial Gravity Impacts to Deep-Space Vehicle Design, JSC/EX Document No. EX-02-50, 2002

  7. Goals and Objectives • Perform parametric study to enhance understanding of propellant and trip time requirements for both a round trip Earth-Mars mission and a Sun-Earth L2 Libration Point mission • Compare results generated using different tools (e.g., VariTOP, RAPTOR, Copernicus, Mystic) • Minimize initial mass in low Earth orbit (IMLEO) • Crewed trip time <700 days • Perform parametric assessment of Mars parking orbit altitude • Determine preferred (minimum propellant mass) orbit apoapse and periapse altitudes for selected semi-major axis altitude targets • Compare against circular orbit altitudes for same semi-major axis target • Understand effect of parking orbit geometry on lander vehicle mass

  8. Round Trip Earth/Mars Mission Mission Overview >30 Day Surface Stay Landing Launch Pre-deployed Mars Lander 500 -> 90,000 km (Elliptical or Circular Orbits) Heliocentric Flight Earth - Mars Heliocentric Flight Mars - Earth Rendezvous/Dock Of Descent/Ascent Vehicle And Mars Transfer Vehicle Mars Crew Transfer Vehicle Constant Thrust Power = 6 MW Efficiency = 60% Isp = 4000 sec Mass Return to Earth = 89 mt Crew Delivery Taxi (Possible Emergency Return Vehicle) HEO 30,000 –> 90,000 km (Circular Orbits) Crew Return Rendezvous/Dock Of Crew Taxi and Mars Transfer Vehicle LEO (700 km) On-orbit Construction of Transfer Vehicle Launch of NEP Transfer Vehicle Launch Of Crew Taxi Launch for Crew Pickup Courtesy: Jerry Condon/JSC

  9. Round Trip Earth/Mars Mission Mission Overview • Spiral NEP Mars transfer vehicle from LEO (700 km) to selected crew transfer orbit (flight crew not onboard) • Crew taxi launches from ground to Mars transfer vehicle (30,000 – 90,000 km) • Crewed mission begins with crew transferred to Mars transfer vehicle above the trapped proton radiation belt • Avoids crew spiral through proton radiation belt • Crew will, however, spiral through the larger trapped electron belt • Mars transfer vehicle spirals from crew transfer orbit to heliocentric orbit targeted to Mars • Mars transfer vehicle transitions from heliocentric space to selected Mars parking orbit (semi-major axis) altitude target (500-90,000 km) • Mars surface stay (>30 days) • After surface mission complete, Mars transfer vehicle spirals from Mars parking orbit (500-90,000 km) to heliocentric space targeted to Earth return • Mars transfer vehicle transitions from heliocentric space to original crew transfer orbit at Earth (30,000 – 90,000 km) for crew pick-up with crew taxi

  10. Earth-Mars Trajectory Analysis Sensitivity StudyExploration Study 1 Follow-on(Three week Quick Study preliminary results) Melissa L. McGuire Robert D. Falck NASA Glenn Research Center 7820 / Systems Analysis Branch February 28, 2003 (Updated March 3, 2002)

  11. Earth-Mars Trajectory Analysis Sensitivity Study Report out of Quick Turnout Study • Trajectory Analysis Methods • Trajectory Sensitivity Study Analysis Methods • Point design case Data and Trajectory Plots • Sensitivity Study results • IMLEO and Total trip time as a function of Mars/Earth orbital altitudes • Table of raw data for sensitivity study

  12. System Assumptions Power: 6 MW Specific Impulse (Isp): 4000 sec Thruster efficiency: 60% Tankage Fraction: 5% Mission Assumptions Mass returned to Earth: 89 mt Launch Date: 2026 Stay time in Mars space: approx 90 days Resulted in stay times at Mars in orbit from 37 to 77 days Mission Total Trip time goal: 700 days Limiting Orbit Assumptions (for sensitivity trade) Earth departure orbit altitude : LEO of 700 km Earth return orbit altitude: vary between 30,000 - 90,000 km Mars parking orbit altitude: vary between LMO of 500 km and aerosynch Earth-Mars Trajectory Analysis Sensitivity Study Mission and System Assumptions

  13. Varitop, JPL low thrust trajectory analysis code Trajectories contain spiral escape at Earth, spiral capture/escape at Mars, spiral capture into Earth orbit upon return Set the final mass at Earth return to 89 mt Set launch date guess to generate a 2026 launch opportunity Earth orbits modeled as circular No constraints on heliocentric orbit proximity to Sun No propellant allotted for Mars orbit operations (eccentricity, inclination, etc. corrections) Four bookend point design cases used Mars stay times of 40 and 70 days for low and high Mars parking Orbit altitude cases respectively These stay times allow for approximately 90 days in Mars vicinity. More refined Mars stay time choices in sensitivity cases Earth-Mars Trajectory Analysis Sensitivity Study Trajectory Analysis Methods

  14. First: Ran a series of Mars parking orbit altitudes from 500 to 17,200 km Second: For each Mars parking orbit, ran a series of Earth return orbits from 30,000 km to 90,000 km altitude For Each trajectory Refined guess for stay time in Mars orbit such that the sum of stay time plus spiral capture time and spiral escape time approximately 90 days Start from a 700 km LEO departure orbit altitude The NEP vehicle flies the whole trajectory from LEO to Earth return capture Total trajectory time includes the spiral from LEO to the high earth orbit altitude (I.e., crew delivery altitude) through Earth escape Earth-Mars Trajectory Analysis Sensitivity Study Trajectory Sensitivity Analysis Methodology

  15. Point Design Assumptions: Earth Departure Orbit: 700 km altitude Earth Return Orbit: 30,000 km altitude Mars Parking Orbit: 500 km altitude Stay Time in Mars Orbit: 40 days Total Trip time includes LEO to high Earth orbit spiral time Point Design Result Highlights (see Table for further details) IMLEO: 303.7 mt Total trip time (with Earth spirals): 744.8 days Earth spiral out/in trip time: 110.7 / 9.6 days Earth spiral out/in propellant cost: 44.5 / 3.9 mt Mars spiral in/out trip time: 28.4 / 26.3 days Mars spiral in/out propellant cost: 11.4 / 10.6 mt Time in Mars Vicinity: 94.7 days Closest approach of trajectory to Sun: 0.39 AU Earth-Mars Trajectory Analysis Sensitivity Study Earth-Mars 500/30,000 Trajectory Point Design

  16. Earth-Mars Trajectory Analysis Sensitivity Study Earth-Mars 2026 (Earth Return 30000 km, Mars Parking Orbit 500 km) Point Design Trajectory Plot • Mission Assumptions: • Earth Departure Orbit: 700 km altitude • Earth Return Orbit: 30,000 km altitude • Mars Parking Orbit: 500 km altitude • Stay Time in Mars Orbit: 40 days • System Assumptions • Power: 6 MW • Specific Impulse (Isp): 4000 sec • Thruster efficiency: 60% • Tankage Fraction: 5% Escape Earth Spiral for 110.7 days November 1, 2026 Mass after spiral: 259.1 mt Close Approach to Sun Distance ~ 0.39 AU Earth Begin Spiral Capture at Mars June 27, 2027 Mass before spiral: 183.5 mt Sun Start at 700 km Earth orbit altitude July 13, 2026 Initial Mass: 303.7 mt Mercury Finish capture at Mars July 25, 2027 Spiral for 28.4 days Capture into 500 km orbit Mass after spiral: 172.1 mt Escape Mars Spiral for 26.3 days September 30, 2027 Mass after spiral: 161.5 mt Capture at Earth July 27, 2028 Orbit altitude 30,000 km Spiral for 9.6 days to capture Mass after spiral: 89 mt Mars Stay time 40 days in Mars orbit Begin Spiral Escape of Mars September 3, 2027 Begin Spiral at Earth return July 17, 2028 Mass before spiral: 92.9 mt Courtesy: Melissa McGuire/GRC, Rob Falck/GRC

  17. Point Design Assumptions: Earth Departure Orbit: 700 km altitude Earth Return Orbit: 90,000 km altitude Mars Parking Orbit: 16,700 km altitude Stay Time in Mars Orbit: 70 days Total Trip time includes LEO to high Earth orbit spiral time Point Design Result Highlights (see Table for further details) IMLEO: 271.6 mt Total trip time (includes Earth spirals): 692.9 days Earth spiral out/in trip time: 98.5 / 2.1 days Earth spiral out/in propellant cost: 40 / 0.86 mt Mars spiral in/out trip time: 6.23/ 6.06 days Mars spiral in/out propellant cost: 2.5 / 2.4 mt Time in Mars Vicinity: 82.3 days Closest approach of trajectory to Sun: 0.398 AU Earth-Mars Trajectory Analysis Sensitivity Study Earth-Mars 16700/90000 Trajectory Point Design

  18. Earth-Mars Trajectory Analysis Sensitivity Study Earth-Mars 2026 (90,000 km Earth return, 16,700 km Mars Parking Orbit)Point Design Trajectory Plot • Mission Assumptions: • Earth Departure Orbit: 700 km altitude • Earth Return Orbit: 90,000 km altitude • Mars Parking Orbit: 16,700 km altitude • Stay Time in Mars Orbit: 70 days • System Assumptions • Power: 6 MW • Specific Impulse (Isp): 4000 sec • Thruster efficiency: 60% • Tankage Fraction: 5% Escape Earth Spiral for 98.5 days November 7, 2026 Mass after spiral: 232.0 mt Close Approach to Sun Distance ~ 0.39 AU Earth Begin Spiral Capture at Mars June 20, 2027 Mass before spiral: 160.8 mt Start at 700 km Earth orbit altitude July 31, 2026 Initial Mass: 271.6 mt Sun Mercury Finish capture at Mars July 27, 2027 Spiral for 6.3 days Capture into 16,700 km orbit Mass after spiral: 158.3 mt Escape Mars Spiral for 6.1 days Sept. 11, 2027 Mass after spiral: 155.9 mt Capture at Earth June 23, 2028 Orbit altitude 90,000 km Spiral for 2.1 days to capture Mass after spiral: 89 mt Mars Stay time 70 days in Mars orbit Begin Spiral Escape of Mars Sept. 5, 2027 Begin Spiral at Earth return July 21, 2028 Mass before spiral: 89.6 mt Courtesy: Melissa McGuire/GRC, Rob Falck/GRC

  19. Earth-Mars Trajectory Analysis Sensitivity Study Earth Mars 2026 Point Design Bookend Cases Data Table Courtesy: Melissa McGuire/GRC, Rob Falck/GRC

  20. Earth Departure Orbit: 700 km altitude Earth Return Orbit: vary from 30,000 to 90,000 km altitude Mars Parking Orbit: vary from 500 to 17,200 km altitude Stay Time in Mars Orbit: calculated to sum time in Mars vicinity to approximately 90 days Resulted in stay times at Mars in orbit from 37 to 77 days Total Trip time includes spiral time from LEO to high Earth orbit Earth-Mars Trajectory Analysis Sensitivity Study Sensitivity Analysis Assumptions

  21. Earth-Mars Trajectory Analysis Sensitivity Study IMLEO vs. Earth Return Orbit Altitude 305 Mars Orbit Mars Stay: 37.0 days Altitudes Mars Spiral: 54.5 days 17200km 10000km 300 Mars Stay: 37.0 days Mars Spiral: 53.6 days 5000km Mars Stay: 37.0 days Mars Spiral: 53.0 days 500km Mars Stay: 37.0 days Mars Spiral: 52.7 days 295 Mars Stay: 37.0 days Mars Spiral: 52.4 days Mars Stay: 60.0 days 290 Mars Spiral: 30.6 days IMLEO (mt) Mars Stay: 60.0 days Mars Spiral: 30.1 days Mars Stay: 70.0 days Mars Stay: 60.0 days 285 Mars Spiral: 20.4 days Mars Spiral: 29.8 days Mars Stay: 60.0 days Mars Spiral: 29.6 days Mars Stay: 70.0 days Mars Stay: 37.0 days Mars Spiral: 20.0 days Mars Spiral: 29.4 days Mars Stay: 70.0 days Mars Spiral: 19.8 days 280 Mars Stay: 70.0 days Mars Spiral: 19.7 days Mars Stay: 70.0 days Mars Stay: 77.0 days Mars Spiral: 19.6 days Mars Spiral: 13.0 days Mars Stay: 77.0 days 275 Mars Spiral: 12.8 days Mars Stay: 77.0 days Mars Spiral: 12.6 days Mars Stay: 77.0 days Mars Spiral: 12.5 days Mars Stay: 77.0 days Mars Spiral: 12.4 days 270 30000 40000 50000 60000 70000 80000 90000 Earth Departure/Return Orbit Altitude (km) Courtesy: Melissa McGuire/GRC, Rob Falck/GRC

  22. Earth-Mars Trajectory Analysis Sensitivity Study Total and Crewed Mission Timevs. Earth Return Orbit Radius Courtesy: Melissa McGuire/GRC, Rob Falck/GRC

  23. Earth-Mars Trajectory Analysis Sensitivity Study Low Thrust NEP Trajectory Trade Space Raw Data Courtesy: Melissa McGuire/GRC Rob Falck/GRC

  24. Missions of 700 round trip are possible with limits on Earth and Mars orbit altitude choices Total trip time does not equal total crew time Note: The astronauts will ascend to the NEP vehicle once it’s in the high earth altitude via a crew taxi Trade studies needed to evaluate choice of Mars parking orbit with respect to Ascent/Descent vehicle versus NEP vehicle performance Note: Appendix D provides some preliminary data Further analysis needed to evaluate proximity to Sun on return leg Earth-Mars Trajectory Analysis Sensitivity Study Observations

  25. Study 2Sun-Earth L2 Libration Point (SE-L2) Mission

  26. Sun-Earth Libration Point (L2) Mission Assumptions • Satellite constellation deploy/maintenance mission • Also, dress rehearsal for Mars mission • Single vehicle - NEP Mars transfer vehicle • No rendezvous at SE-L2 • Target => SE-L2 • Use same vehicle specifications as last year study for Mars transfer vehicle • Power = 6 Mw • Engine efficiency = 0.6 • Isp = 4000 sec • No thrust vector turning constraints • Final mass target (back at Earth) =89mt • Mission • Opportunity independent - selectable stay time at SE-L2 (independent of Earth departure time) • Crew transfer altitude designed to keep crew out of trapped proton radiation belt

  27. Sun-Earth Libration Point (L2) Mission Mission Overview SE-L2 Operations Sun-Earth L2 Libration Point (SE-L2) Mars Crew Transfer Vehicle Constant Thrust Power = 6 MW Efficiency = 60% Isp = 4000 sec Mass Return to Earth = 89 mt Trans SE-L2 Flight Trans-Earth Flight Crew Delivery Taxi (Possible Emergency Return Vehicle) HEO 30,000 –> 90,000 km (Circular Orbits) Crew Return Rendezvous/Dock Of Crew Taxi and Mars Transfer Vehicle LEO (700 km) On-orbit Construction of Transfer Vehicle Launch of NEP Transfer Vehicle Launch Of Crew Taxi Launch for Crew Pickup Courtesy: Jerry Condon / JSC/EG5

  28. Sun-Earth Libration Point (L2) Mission Mission Overview • Spiral NEP ‘Mars’ transfer vehicle from LEO (700 km) to selected crew transfer orbit (flight crew not onboard) • Note: The Mars transfer vehicle is used for this mission to Sun-Earth L2 (SE-L2) • In addition to meeting planned objectives, the SE-L2 mission could provide a proving ground for future Mars missions • Crew taxi launches from ground to Mars transfer vehicle (30,000 – 90,000 km) • Crewed mission begins with crew transferred to Mars transfer vehicle above the trapped proton radiation belt • Avoids crew spiral through proton radiation belt • Crew will, however, spiral through the larger trapped electron belt • Mars transfer vehicle spirals from crew transfer orbit to SE-L2 • Variable stay time at L2 • Mars transfer vehicle returns crew from SE-L2 to original crew transfer orbit at Earth (30,000 – 90,000 km) for crew pick-up with crew taxi

  29. Sun-Earth Libration Point (L2) Mission Study Methodology • Trajectory tool used: Copernicus • Multi-body, multi-spacecraft, continuous thrust trajectory tool in development at University of Texas – Center for Space Research • Mission - trajectories were solved backwards (from end of mission to beginning) in order to determine required IMLEO needed to conclude mission with an 89 mt mass • Mission segments: • Return trip from SE-L2 to crew transfer altitude (30,000 – 90,000 km) • Outbound trip from 100,000 km to SE-L2 • Spiral up from 700 km initial circular Earth parking orbit to 100,000 km circular orbit • Mass matching performed for the vehicle at 100,000 km altitude

  30. Sun-Earth Libration Point (L2) Mission IMLEO and Trip Time vs. Crew Altitude

  31. Sun-Earth Libration Point (L2) Mission Tabular Trajectory Data

  32. Future Work • Complete RAPTOR mission set • Compare and contrast results with VariTOP • Review Mars parking orbit parametric study • Evaluate sudden change in eccentricity at 38,000 km altitude range

  33. Appendices

  34. Appendix A Mars Arrival Parking Orbit Analysis Earth-Mars Round Trip Mission Comparison of Elliptical vs. Circular Mars Parking Orbit Arrival Kyle Brewer / JSC/EG5 March 3, 2003

  35. Mars Arrival Parking Orbit Analysis Purpose • Provide a comparison of insertion into Circular vs. Elliptical orbits at Mars based on a state vector from a fully integrated roundtrip mission provided by JPL

  36. Mars Arrival Parking Orbit Analysis Assumptions • Same Vehicle specifications as previous study • The JPL mission is optimized for the following roundtrip mission: • Depart 30,000 km Earth orbit • Arrive/Stay Depart Aerosynchronous (17,048 km alt) orbit • Arrive 30,000 km Earth orbit • Initial state vector and mass taken from beginning of Mars approach burn (see next slide) • Given that the state and mass are not optimized for the variety of orbits analyzed, the resulting data should be considered for comparative purposes only.

  37. Mars Arrival Parking Orbit Analysis Initial State from JPL Initial State taken from this point

  38. Mars Arrival Parking Orbit Analysis Methodology • Trajectory tool used: Copernicus • Multi-body, multi-spacecraft, continuous thrust trajectory tool in development at University of Texas – Center for Space Research • Trajectories to circular orbits were computed by specifying the desired orbit radius and constraining the eccentricity to 0.0 and solving for minimum thrusting time • Optimum eccentricity orbits were determined by holding only the desired Semi-Major Axis constant and solving for minimum thrusting time to meet that SMA constraint

  39. Mars Arrival Parking Orbit Analysis Prop Usage for Circular and Opt. Ecc Orbits

  40. Mars Arrival Parking Orbit Analysis Optimum Eccentricity and Ha/Hp

  41. SMA = 30000 km SMA = 39600 km SMA = 42000 km Mars Arrival Parking Orbit Analysis Observations • A large jump in optimum eccentricity is seen around the target SMA of 39,000 km • This is the target about which the powered trajectory makes it’s first complete pass around the planet (SMA shown is an altitude)

  42. Mars Arrival Parking Orbit Analysis Tabular Trajectory Data

  43. Appendix B Mars Parking Orbit Lifetime Carlos Westhelle / EG5 March 3, 2003

  44. Mars Parking Orbit Lifetime Orbit Lifetime at Mars - Introduction • Current Mars ascent vehicle targeted to 200 km temporary parking orbit • Off-nominal situations (e.g. failure of subsequent engine firing) may require extended stay in this orbit • This lifetime study takes a quick look at the parking orbit lifetime as a function of altitude range (130-200 km) for a range of possible vehicle ballistic numbers (150-1500 kg/m2)

  45. Mars Parking Orbit Lifetime Orbit Lifetime at Mars - Methodology • STK-Astrogator was used to propagate the vehicle with a Mars GRAM atmosphere model • Orbit was propagated until it decayed to a 125 km altitude (Mars entry interface) up to a maximum time cutoff of 365 days • For orbit propagations reaching this 365 day limit, the resulting orbit altitudes are noted on the plot on the next slide

  46. Mars Parking Orbit Lifetime Orbit Lifetime at Mars Courtesy: Carlos Westhelle / JSC-EG5

  47. Mars Parking Orbit Lifetime Orbit Lifetime at Mars – Observations • A 200 km circular Mars parking orbit provides sufficient time (> 365 days) for an extended stay for a worst-case ballistic number (i.e., 150 kg/m2) • Note: For this case the vehicle will decay to Mars entry interface (125 km) in approximately another 40 days

  48. Appendix C Integrated Reference Mission – JPL Greg Whiffen/JPL February 23, 2003

  49. Mission Design and Results • Single end to end multi-body integrated trajectory using Mystic • Trajectory characteristics: • Start escape spiral at 30,000 km altitude Earth orbit, 224 metric tons, September 8, 2026 • Escape Earth, 209.9 metric tons, October 24, 2026 • Capture Mars-begin spiral, 178.1 metric tons,July 18, 2027 • Areosynchronous orbit 40 days, 173.3 metric tons, July 30 through Sept 8, 2027 • Mars escape, 171.4 metric tons, September 19, 2027 • Earth capture, 104.1 metric tons, July 10, 2028 • Earth 30,000 km altitude orbit, 97.6 metric tons, July 26, 2028 • Vehicle characteristics: • Power = 6 MW, Efficiency = 60%, Isp = 4000 seconds • Trajectory results: • Total flight time is 687 days from 30,000 km altitude Earth orbit to a return 30,000 km altitude Earth orbit • Time spent in low mars orbit is 40 days. • Dry mass with tankage is 97.567 metric tons • Total propellant used is 126.433 metric tons • 5% tankage is 6.322 metric tons • Net Mass without tankage 91.245 metric tons

  50. Courtesy: Greg Whiffen/JPL

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