Descent GN&C - Telecommunicatons & Payload

Home , First Lunar Outpost, Lander (spacecraft)

Small Spacecraft in support of the Lunar Exploration Program

9th ILEWG Conference Sorrento, 24.10.07

At NASA: Richard Bornhorst, James Brown, James Bell, Joe Camisa, Sylvia Cox, Howard Cannon, Robert Dumais, Ian Fernandez, Ken Galal, Robert Hanel, Butler Hine, James Kennon, Kalmanje Krishnakumar, Lynette O-Leary, Lawence Lemke, Mark Mallinson, William Marshall, Owen Nishioka, Craig Pires, Steven Spremo, Mark Turner, Alan Weston and Pete Worden At Raytheon: Craig Baker, Ronald Choo, James Head and Leonard Vance; At Stellar Exploration Inc.: Tomas Svitek Content Overview 1. Small Spacecraft Advantages and Limitations

2. LRAS and Small Spacecraft

3. The Micro Lunar Lander - Introduction and Mission Objectives - Launch, trajectory and stack - Spacecraft Structure - Propulsion - Power - Descent GN&C - Telecommunicatons & Payload

4. Excursion Designs - Featherlight Lander - Small Lander - Comms Orbiter 5. Conclusions

6. Lunar Science Institute 1. Small Spacecraft Advantages and Limitations

Key Characteristics of Small Spacecraft Missions* 1. Low cost (~ $50-100M) 2. Fast turn around (12-36 months from ATP to launch) 3. Use of latest technology 4. Use of next generation of affordable launch vehicles (Minotaur V and Falcon I) 5. Use off-the-shelf technologies wherever possible (commercial and other) 6. Leveraging technologies from the US Department of Defense (DoD) 7. Higher risk missions (Class D as per NPR 7120.5D)

* As conceived by NASA-Ames Small Spacecraft Office for the class of missions focused upon there. 1. Small Spacecraft Advantages and Limitations

Key Advantages of Small Spacecraft 1. Low Cost 2. Decreased schedule 3. Increased number of missions (as a result of (1) and (2)), allowing: a. A fast learning cycle for spacecraft development b. High public participation and attention c. Many opportunities for international collaboration d. Exciting focal points for youth e. A small overall program risk f. Ability to do more high-risk missions (e.g. test low TRL tech.) Key Limitations of Small Spacecraft 1. Size and mass constraint make small spacecraft not directly useful for some set missions. E.g. heavy ISRU 2. Higher risk per mission --> potential negative political ramiﬁcations 3. Reliance on yet to be proven launch vehicles, or on being a secondary payload on a larger mission 4. Sometimes more expensive per unit mass of spacecraft 2. LRAS and Small Spacecraft

Mission 2: Fixed Lander Mission 4: Mobile Lander • Precision landing LRAS Baseline • Water presence in 20 sites of shadowed crater • Dust characterization Architecture • Radiation Shielding of Regolith • Regolith composition and thickness Mission 1: LRO-like • Effects of lunar environment on life and mechanical structures • Lighting and thermal ground truth • Visual & topographical maps Mission 3: Comms Orbiter • Hydrogen map • Partial coverage of the South Polar region • Radiation environment 7th (?) Human Landing X 2006 2008 2010 2012 2014 2016 2018

Mission 1: LRO/LCROSS (large) Mission 10: Lander Rover (large) • Visual & topographical maps • ISRU of O2 and H2O (produce up to 1000kg) • Hydrogen map • Fluid experiment • Radiation environment • 30 km roving on north or south pole Mission 8 & 9: Hopper Lander (small) Mission 2: Laser Comms Demo (small) • Water presence in 20 sites of shadowed crater (both poles) • Laser Communications Demonstration • Radiation Shielding of Regolith • Frozen orbits validation Mission 3&4: Fixed Lander (x2 small)• Effects of lunar environment on life and mechanical structures • High altitude dust(?) • Precision landing Mission 5, 6, 7: Comms Orbiters (x3 small) • High resolution neutron spec. (?) • Dust characterization • Full coverage of south poles Small Spacecraft • Lighting and thermal ground truth Architecture ISRU and Tele-robotic Phase? • Public Participation • Series of small ISRU demonstrators • Regolith composition and thickness • Series of increasingly capable tele-robotically operated landers 3. Micro Lunar Lander

Basics Mass ~100kg Cost <$100M Development time <36 months ATP to launch

Also: - Use of off-the-shelf technology - Leveraging DoD technology (e.g. KKV, DSMAC, XSS software) 3. Micro Lunar Lander

Objectives Political: 1. “Beginning no later than 2008, we will send a series of robotic missions to the lunar surface to research and prepare for future human exploration.” (VSE) 2. Steps towards “goal of living and working there for increasingly extended periods” --> resources and the potential location for the outpost Managerial: 4. To successfully develop and deploy a soft-landing spacecraft with a) Timescale: < 36 month from ATP to launch b) Cost: < $100M (including launch) Technical: 5. Retire technical risks for human lander missions (landing algorithms) 6. Demonstrate landing precision of <1km, 1σ. Scientiﬁc: 7. To investigate, if possible: (a) The Lunar Dust characteristics; (b) The Hydrogen quantity and form in the regolith Public Exploration: 8. To provide real public participation in the mission, e.g. video data streaming 3. Micro Lunar Lander

Mission Planning Launch Vehicle: Minotaur V [= 464 kg to TLI] Trajectory: Hohmann (~5 day) Mission Duration: 12 days + 1 hour into dusk (1+ years at polar sites) Design Constraint: Designed to potentially be launched on a Falcon 1 Descent: In close accordance with NASA-JSC descent algorithm 3. Micro Lunar Lander

Launch 3. Micro Lunar Lander

Structure

Table 4 SUMMARY OF STRUCTURE TRADES Trade Description Results Spacecraft launch orientation Legs down (“Live bug”) Two Tanks vs. Four Tanks Four tanks Number of Lander legs (3 vs. 4) Four legs Leg Construction (Struts vs. Beams) Struts Structure Ty pe (Space frame Truss structure vs. Sandwich Hybrid Panels) Materials for truss structure (Composite vs. Metal) Carbon tube/ Al fittings Joint Design Trade (Tabs vs. Ball vs. One Bolt vs. Down-selected to Weldments vs. Slip Joint Node Fittings vs. Monolithic Tabs & Ball Machined Joi nt Equipment Layout (two independent modular primary Independent subsystems of Propulsion and common bus vs. integrated) modular Fixed vs. retractable legs Fixed

3. Micro Lunar Lander Propulsion - Descent thruster. KKV derived light weight pulsed modular thrust systems developed for missile defense. - + 6 attitude control thrusters, 1 fuel tank, 1 oxidizer tank, 1 pressurant tankFour ACS thrusters are arranged in a bow-tie conﬁguration for attitude control. Two ACS thrusters are oriented vertically to ΔV for the TCMs

Descent motor maximum Thrust (Tmax):3200 ± 500 N Descent motor Speciﬁc Impulse: 292 ± 10 s

ACS motor Maximum Thrust (Tmax): 30 ± 10 N ACS motor Speciﬁc Impulse: 266 ± 10 s Propulsion System Mass Wet: 21 kg Usable Propellant Mass: 13 kg This propulsion system is designed to provide the ΔV = 728 m/s required for the combination of ACS, TCMs and descent onto the lunar surface. 3. Micro Lunar Lander Descent GN&C 3. Micro Lunar Lander Descent GN&C Descent guidance is based on an altitude-velocity constraint This is a conservative descent velocity guidance that ensures a safe altitude-based velocity profile. The guidance logic is as follows: o Main Thruster is turned on if descent velocity magnitude is larger than the green line magnitude for the corresponding altitude. • Main Thruster is turned off if descent velocity magnitude is smaller than the red line magnitude for the corresponding altitude.

Initial conditions* Initial Height = 2365 mts Initial Descent Velocity = 61 m/s Initial Down Range Velocity = 145 m/s Initial Pitch Angle = 22.8 degs Time of flight = 84 s

* First Lunar Outpost Powered Descent Design and Performance, Engineering Directorate, Systems Engineering Division, August 1992, NASA JSC-25882 3. Micro Lunar Lander Descent GN&C -- Results 3. Micro Lunar Lander

Power 3. Micro Lunar Lander Telecoms S/C: Omni-directional, S-band, 0.1 kg Ground: DSN Bit Rate: 50 kbps Payload - Design project goal was to confirm technically feasible to bring a useful payload mass to the lunar surface given the constraints applied, (not to fulfill a particular scientific or technical mission). - Payload mass suffices for instruments for the large majority of LRAS objectives. - Instruments most likely to be considered: 1. Stereoscopic Camera 2. Dust Characterization Instrument 3. Neutron spectrometer (local Hydrogen content + ground truth orbital data) 4. Higher gain antenna (to stream descent imagery data for outreach) 5. LIDAR and other descent hardware tech demo for human landers

Cost: $88 M 4. Excursion Designs

•Bus Module

•Orbiter

•Payload Module

•Extension Module •Baseline/Small Lander

•Propulsion Module

•Legs

•Featherweight Lander 5. Conclusion Design project concludes that it is technically feasible to land useful payloads (10- 15kg) to the lunar surface using low mass spacecraft (86kg), very affordably (~$88M) and with a fast turn around (<36 months). These ﬁgures are for a ﬁrst such mission: further ones would improve on this.

Some more general conclusions one might extrapolate: 1. Small spacecraft could do the same technical functions as the existing Missions 1-4 in the LRAS baseline at a fraction of the cost schedule of the missions planned therein. (14 of 15 objectives) 2. Each mission has higher risk but more missions reduces programmatic risk. 3. Small missions--> faster learning cycle --> reduce cost and schedule risks with future larger mass missions (reduce technology risk for Constellation program) 4. Shorter schedule allow a phase of tele-robotic and ISRU missions prior to human landing which could enhance their capabilities and safety. 5. Such missions are readily able to meet key political objectives in VSE

Email: william.s.marshall@nasa.gov 6. NASA Lunar Science Institute (NLSI)

• NLSI Announced on 9th October by Dr. Alan Stern, NASA Science Mission Directorate Associate Administrator • 4-5 Lead Teams • $1-2 million / team • Modeled after the NASA Astrobiology Institute (NAI) • Managed by NASA-Ames Research Center (as is the case for NAI)