Intro
This study continues the 2005 SpaceDev Study: ‘Human Service Mission to the ILO,” and explores in more detail ways for the crew members to move from one facility to another within a few kilometers of the base camp, as well as move between the base camp to possible water sites in a deep crater at the Lunar South Pole, or in the permanently shadowed slope of Malapert Mountain. There also is a secondary focus on analyzing the capabilities and requirements related to Dream Chaser Lunar fly-by missions consisting of at least two people.
Since the 2005 study, the Dream Chaser design concept has matured to include adoption of the Common Hybrid Propulsion Module (CHPM) concept and a CHPM based launch vehicle. SpaceDev was also selected as finalist in NASA Commercial Orbital Transportation System (COTS) competition.
Assumptions
Lunar Surface Transportation: facilities at base camp within a 20 km radius, water ice exploration range of 150 km. Moon base transitioning to in-situ resource utilization, with a few habitation modules and lab complexes experimenting with techniques for lunar regolith resource extraction. ILO is positioned near Moon base, all near Malapert Mountain. Base will consist of international and private cooperation.
Dream Chaser fly-around: at most one day in low earth orbit and eight days for the lunar swing-by and return home, Dream Chaser will aero brake from Lunar Free Return trajectory, re-enter and land
Results
Lunar Surface Rover
Autonomous Lunar Orbit Hopper Architecture (ALOHA): a 300 kg chair-like structure with 1,633 kg fuel, which contains enough propellant for a roundtrip between LLO and the lunar surface and docking with capsule in LLO; capable of sub-orbital hop of up to 150 km for soft landing in cold trap. There is a possible consideration to land the ILO with ALOHA. An ALOHA passenger would be required to wear a spacesuit w/oxygen.
Earth-to-Moon Transportation is enabled by the Dream Chaser vehicle, which relies on SpaceDev’s hybrid propulsion module (easy-to-manufacture, reliable and low-cost). The Dream Chaser launch vehicle is a multi-stage stack composed of 32 CHPMs: Stage 1 is a cluster of 19 CHPMs, jettisoned as a single unit; Stage 2 is composed of 8 CHPMs, jettisoned in pairs; and Stage 3b consists of 4 CHPMs attached in parallel to the sustainer Stage 3s, which is a single central module attached to the Dream Chaser. Stages 2 and 3 are nested together to reduce drag, stack height and flight bending loads.
Dream Chaser XL is modified (enlarged) to accommodate a lunar mission, and includes 10% larger than the orbital design and 30% increase in interior volume. The larger volume allows more storage of life support consumables like air and water. The reinforced thermal protection system is ablative (vs. reusable on original Dream Chaser) and will allow it to survive the higher energy lunar re-entry (structure limit of 350°F). A modified upper stage grants extra mass to docking structure, solar panels and thermal radiators, which increases mission duration to nine (9) days (one day for rendezvous in LEO and eight days for lunar swingby).
Going Forward
In conclusion, SpaceDev looks into four potential future studies:
ALOHA development
Develop & demonstrate hovering craft hardware & control system
Develop & demonstrate software for autonomous lunar landing
Geo-stationary Communications Relay Satellite
Small Satellite in GEO to relay communications
Minimal eclipse times
Could reduce size of earth based antennas
Autonomous Rendezvous and Docking
DARPA Orbital Express will demonstrate autonomous docking
Launch is scheduled for 1st Quarter of 2007
Starsys Research Corporation is developing hardware for the capture mechanism
SpaceDev now has in-house robotics expertise
Dream Chaser Development Follow On
Common sub-orbital and orbital/lunar configuration
CHPM sizing and development
Orbital launch system definition
RCS system definition
Docking compatibility with ISS and Bigelow