Mars for Less by HC111208224713

VIEWS: 7 PAGES: 28

									       Mars for Less
Human Mars Expeditions with Existing
         Launch Vehicles

                     Grant Bonin
             4Frontiers Corporation
           gbonin@4FrontiersCorp.com




     SpaceVision 2006, Orlando Florida, November 10-12
Who is this guy?
Rick Tumlinson
                                                              Brian Enke



Bob Richards




                                                             Joe (my boss)


George                                       me
Whitesides
                 SpaceVision 2006, Orlando, Florida, November 10-12
Problem Statement
• How do we get off this rock?
• More specifically, how do we get off this rock and to other ones?
• We need:
    1.   Improved life support technologies
    2.   Better understanding of spaceflight physiology
    3.   Space-based nuclear power
    4.   Better understanding of EDL of massive payloads
    5.   <… insert additional items, probably your work, here…>
    6.   A way to get it all off the ground in the first place
    7.   $$$

• This presentation deals with the last two items




                  SpaceVision 2006, Orlando, Florida, November 10-12
Presentation Outline
• Background and Motivation
    – Heavy Lift Launch Vehicles (HLLVs)

• Mars for Less
    –   Mission Overview
    –   Trajectories and Energy Requirements
    –   Propulsion System Design
    –   Spacecraft Sizing
    –   Lunar Exploration Options

• The Launch Vehicle Debate
    –   The Case for Heavy-Lift
    –   The Case for Smaller Launch Vehicles
    –   Risks and Arguments
    –   The Bottom Line

• Summary, Conclusions and Questions


                     SpaceVision 2006, Orlando, Florida, November 10-12
Getting off this rock…




                           [Source: AIAA-2006-7517]


         SpaceVision 2006, Orlando, Florida, November 10-12
Background
• Heavy-Lift Launch Vehicles
• Existing Plans (Ares V) – at ―crux‖ of NASA ESAS
• Issues
   – Development Delays
   – Political Uncertainty
   – Role of the Private Sector

Does losing heavy-lift mean losing our shot at Mars?




                SpaceVision 2006, Orlando, Florida, November 10-12
Mars for Less
• MFL circumvents heavy-lift vehicles entirely
• The ―heavy-lift alternative‖
• Key design features:
    –   Existing or near-term launch vehicles (MLLV class, ~25 MT ETO)
    –   Existing or near-term technologies
    –   Only orbital assembly: no orbital construction
    –   Subset of vehicles can be used for long-duration lunar missions

Here’s how the mission works…




                   SpaceVision 2006, Orlando, Florida, November 10-12
Mars for Less
• Modular version of Mars Direct
• Assembled in orbit using existing launch vehicles
• two spacecraft per complete mission:

• Earth Return Vehicle (ERV)
   – Launched to Mars unmanned
   – Produces propellant on Mars

• Mars Transfer and Surface Vehicle (MTSV)
   – Crew transfer to Mars
   – Long-duration surface habitat




                SpaceVision 2006, Orlando, Florida, November 10-12
Mars for Less
• Each spacecraft requires 6 launches to deploy:




      Launch 6   Launch 5        Launch 4        Launch 3        Launch 1 & 2




                 SpaceVision 2006, Orlando, Florida, November 10-12
Mars for Less
• Propulsion stages used at successive perigees for TMI

• Earth Return Vehicle:
   – Hohmann transfer to Mars
   – Aerocapture and parachute/powered descent
   – Methane/oxygen production on surface

• Mars Transfer and Surface Vehicle:
   – Fast conjunction transfer to Mars
   – Aerocapture and parachute/powered descent
   – 500 day surface stay




               SpaceVision 2006, Orlando, Florida, November 10-12
Mars for Less
•   Mating propulsion stages = operationally complex
•   However, mission = developmentally simpler
•   No new launch technology
•   Relies only on orbital docking/rendezvous
•   Think ―Lego‖ (non-ISS)
•   Orbital assembly is most time-tested mission req.
•   Spacecraft can be delivered by many boosters:
      –   Delta IV
      –   Ariane V
      –   Falcon 9-S9
      –   Proton
      –   Crew Launch Vehicle



                    SpaceVision 2006, Orlando, Florida, November 10-12
Trajectories and Energy Requirements
•   Standard split mission profile
•   Forward deployment of cargo (C3 = 15 km2/s2)
•   Fast flight, free return option for crew (C3 = 25 km2/s2)
•   ΔV requirements (incl. 5% gravity losses): 4.1 km/s & 4.5 km/s




                 SpaceVision 2006, Orlando, Florida, November 10-12
Propulsion System Design (I): Design Overview
• 4-stage hydrogen/oxygen propulsion system
• Stage Characteristics:
   – Dry Mass = 3 tonnes
   – Wet Mass = 25 tonnes
   – 2 Pratt & Whitney RL-10B-2 Engines
       • 220 kN total thrust
       • Vacuum Isp = 465 s
   – 1 kWe autonomous PVA (tentative)
• Trans-Mars throw (excluding boiloff losses):
   – 55,077 kg (C3 = 15)
   – 47,607 kg (C3 = 25)




                 SpaceVision 2006, Orlando, Florida, November 10-12
Propulsion System Design (II): Boiloff Sensitivity
• Sensitivity of propulsion system to varying boiloff rates assessed


                27
                26
  C3 (km2/s2)




                25
                24
                23
                           1%
                22
                21         2%
                20         3%
                19
                     0     1     2      3     4     5        6    7

                         Propulsion Assembly Time (months)
Propulsion System Design (III): Conclusions
•   Mass loss rates ≤ 1%/month realistic
•   4-month critical propulsion assembly time
•   Resulting requirement: 1 launch/month
•   Adjusted TMI throw:
      – 54 tonnes for cargo missions
      – 46 tonnes for crewed missions

• Conclusion: boiloff is not a showstopper




                   SpaceVision 2006, Orlando, Florida, November 10-12
Spacecraft Sizing Iterations
• Sizing assumptions:
   –   Lander & integral propulsion Isp = 380s (CH4/LOX)
   –   Lander dry mass = 10% of surface payload total
   –   Aeroshield mass = 15% of entry mass
   –   CH4/LOX stage fractions = 8%

• Two sizing iterations performed:
   – 1st iteration based on past studies
   – 2nd iteration based on OTS components and statistical data

• Estimates converged on similar values
• Most conservative estimates used




                  SpaceVision 2006, Orlando, Florida, November 10-12
Lunar Mission Implementation
• Mars for Less vehicles can be used in long-duration lunar missions
• Concurrently or as precursor
• 2 vehicles used:

• Lunar Transfer Vehicle (LTV)
   – Identical to ERV cabin, upper stage, lander
   – 3-day transfer with free-return option

• Lunar Surface Vehicle (LSV)
   – Forward deployed to lunar surface
   – Utilizes 90-day transfer




                SpaceVision 2006, Orlando, Florida, November 10-12


                            MOON
Lunar Mission Implementation
• Lunar Surface Vehicle
   –   Weak stability boundary transfer
   –   Utilizes ballistic capture
   –   ~25% ΔV reduction
   –   Can support three 150-day expeditions

• Lunar Transfer Vehicle
   – Conventional Transfer
   – Utilizes propulsive capture
   – Ascent to lunar orbit & Earth return capability

• Each spacecraft requires 4 launches
• Long-duration exploration
• Rapid buildup of surface base

                  SpaceVision 2006, Orlando, Florida, November 10-12


                              MOON
The Launch Vehicle Debate
• Small vs. Heavy
   – Payload Fraction
   – Reduced Launch Volume

• Risks and Arguments
   – Multiple Launch and Assembly issues
   – Launch Delays
   – LEO wait time

• The Bottom Line
   – Launch Vehicle Economics
   – Recommendations



              SpaceVision 2006, Orlando, Florida, November 10-12
Multiple Launches
• Multiple launches frequency cited as great weakness
• May be plan’s greatest strength
• HLLV Loss:
    –   Loss of crew;
    –   Loss of spacecraft;
    –   Loss of mission;
    –   Delay (possible loss) of program

• MLLV loss:
    – Component (replaceable if not crewed)
    – Offset by replacing with different booster

• Launch failure in MFL less likely to be mission or program critical


                   SpaceVision 2006, Orlando, Florida, November 10-12
Propulsion System Failure
•   Propulsion stage failure less decisive
•   Possibility of backup stage—depends on situation
•   Single engine reliability ~ 99%
•   2 engines per stage
•   Probability of stage failure ~ 1/10,000
•   Negligible portion of mission risk




                  SpaceVision 2006, Orlando, Florida, November 10-12
Launch Delays and Loiter Time
•   Delays and wait time are always an issue
•   Mars for Less = significant margin
•   4-month propulsion assembly time
•   Indefinite prior spacecraft assembly time
•   (Delays actually increase performance)




                  SpaceVision 2006, Orlando, Florida, November 10-12
Launch Vehicle Economics
• HLLV:
    –   Large capital investment
    –   Poor cost amortization
    –   High man-hours per flight
    –   No market, less chance of competitor involvement
    –   Puts cost of entry for Mars out of reach

• MLLV:
    –   Smaller capital investment (if necessary)
    –   Better cost amortization
    –   Reduced man-hours per flight
    –   Three rules of rocketry:
          –flight rate, flight rate, flight rate!
    – Existing market, high chance of competitor involvement
    – Lowers cost of entry for Mars mission

Why continue to under-utilize existing infrastructure?


                         SpaceVision 2006, Orlando, Florida, November 10-12
Problem Statement
• How do we get off this rock?
• We need:
   1.   Improved life support technologies
   2.   Better understanding of spaceflight physiology
   3.   Space-based nuclear power
   4.   Better understanding of EDL of massive payloads
   5.   <… insert additional items, probably your work, here…>
   6.   A way to get it all off the ground in the first place
   7.   $$$

• By circumventing HLLV, we free up $$$ for all other items




                 SpaceVision 2006, Orlando, Florida, November 10-12
The Bottom Line
• In summary:
      – Mars for less predicated on MLLVs and orbital assembly
      – No orbital construction, fuel transfer, etc.
      – Without new launcher, only Mars-bound spacecraft need development

•   HLLVs will represent ideal technology when market exists
•   That market must first be created
•   Destination drives transportation
•   The bottom line: Use what we have, and fly sooner




                  SpaceVision 2006, Orlando, Florida, November 10-12
Final Remarks
[...] the issue of whether or not such a heavy-lift vehicle is the correct strategic
path remains unresolved. There are valid arguments on both sides, and this is a
hotly debated issue. Fundamentally, the correct answer depends on your
objective. If your primary goal is to place humans on the Moon or Mars, as soon
as possible in the simplest and lowest risk manner, a super-heavy-lift vehicle is
arguably the answer. However, if your primary objective is to open up the
frontier to large numbers of people, or to produce large reductions in launch
costs, or to increase competition and create redundant pathways to space, or to
create a breakthrough in space commerce for the benefit of humankind, or to
settle this new frontier, then logic and history suggests a different choice.

Space Frontier Foundation, July 2006




                     SpaceVision 2006, Orlando, Florida, November 10-12
Final Remarks
•   Mars for Less designed to answer question:

    Can human Mars missions be accomplished with
      existing launch vehicles?

•   The answer is yes.
•   There’s more than one way to the red planet
•   This generation can reach Mars, with less




              SpaceVision 2006, Orlando, Florida, November 10-12
…Questions?

The author would like to acknowledge the following
individuals for their invaluable assistance and contributions:
- Joe Palaia
- Brian Enke
- Frank Crossman
- Regan Walker
- Tarik Kaya
- and the organizers of SpaceVision 2006




                SpaceVision 2006, Orlando, Florida, November 10-12

								
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