Lunar Mission BW1 | Institute of Space Systems

	Introduction
	Mission Objective
	Mission Facts

Introduction

At present, 10 missions (Chandrayaan-1, Chang’e-1, Lunar-A, Lunar Mission BW1, Lunar Reconnaissance Orbiter, Moonlights, Moonrise, Selene, Selene-B, Smart-1) are on their way to the Moon, under development or planned within the next decade. All of these projects from different nations demonstrate that our closest neighbour in space is back in the focus of space activities especially after the announcements of the US-government in January 2004.
Most of the above mentioned missions have scientific objectives to perform further lunar research or to prepare future human exploration. Before humans will return to the Moon for temporary or permanent presence robotic missions will pave the way stepwise:
• Specific robotic missions
• Long-term and permanent automated stations or robotic vehicles
• Automated in-situ resource utilisation

For future robotic and human lunar activities agency roadmaps and programmes [2, 3, 4] and studies (e.g. done by ISU [9, 10]) show the demands of precursor missions for technology demonstration and validation as well as infrastructure missions for lunar development. Infrastructure tasks are e.g. communication, relay functions, navigation, search & rescue and space environment monitoring.
Small satellites are possible low-cost, short-term, demand-responsive tools to fulfill task-tailored objectives.

Mission Objectives

Possible demands of future lunar exploration and development are infrastructure as well as technology validation and specific scientific missions. Main objective is to demonstrate that small satellites are useful low-cost tools to accomplish some exploration and development missions in spite of its limitation.

Potential identified technology demonstration topics are:
• electric propulsion systems for complex attitude control and orbit transfer manoeuvres using autonomous guidance and navigation;
• visible/near-infrared and thermal infrared imaging combined with target pointing observation;
• radio frequency and microwave technology for broadband communication, relay functions and radar sounding;
• new advanced computer architectures for enhanced on-board processing capabilities, evaluation of degradation effects on satellite subsystems.

Possible identified scientific targets in cislunar and lunar space are:
• high resolution multispectral data of selected areas of the lunar surface for mineralogical observation, search for polar water and future landing site selection as well as remnant localisation;
• reflectance measurement and illumination observation of the lunar surface;
• gravitational and magnetic field as well as radiation measurements;
• observation of near earth objects and the Kordylewski clouds.

Mission Facts

Mass:	less than 200 kg
Payload:	~15-20% (incl. monitorig sensors)
Size:	~ 1 x 1 x 1 m³ (in launch configuration)
Power:	max. 1 kW max. 6 m² solar panels
Propulsion:	• thermal arcjet • four or more pulsed plasma thrusters (PPT)

The satellite will be launched as a piggyback payload into a Geosynchronous Transfer Orbit (GTO).
The mission is divided into the following phases:

I.	Launch Phase: Separation from launcher, initial operations and systems check-out propulsion system in use: none
II.	Ascent Phase: Increase the Earth orbit above the Van Allen Belt using the high-thrust electric propulsion system propulsion system in use: Arcjet (100mN thrust, 1kW power consumption)
III.	Cruise Phase: Orbit extension up to lunar gravitational sphere of influence propulsion system in use: Pulsed-Plasma-thrusters (PPT) (6mN thrust, 4x62W=250W power consumption)
IV.	Capture Phase: Insertion into highly elliptical lunar orbit propulsion system in use: Arcjet
V.	Descent Phase: Transfer of the satellite into a high inclined, circular orbit (~100 km altitude) propulsion system in use: Pulsed-Plasma-Thruster
VI.	Science Phase: Remote sensing of the surface of the Moon propulsion system in use: mostly none (stable orbit; also increased energy demand by scientific instruments and data transfer, ~300W)
VII.	Impact Phase: Controlled impact of the satellite onto the lunar surface propulsion system in use: Arcject

The overall travel time of the satellite is dependent on the applied thrust-strategy. Two years flight time or more is possible followed by a six month operations phase in a low lunar orbit with high inclination.

Lunar Mission BW1 - Mission