M

Wireless Spacecraft Communication

Motivation:

Statistics show that the spacecraft harness (wiring) accounts for a significant proportion of a spacecrafts dry mass. Typically this figure ranges from 6% to 10% independent of the size and type of mission. On the mass statistics alone, it is clear that spacecraft harness has to be reduced to the largest extent possible. However, there are other problems with the harness that need to be addressed, including: difficult and labour intensive to manufacture, expensive, difficult to assembly, integrate and test (A-I-T), and difficult post-integration testing. The main motivations for adopting a wireless data communications infrastructure onboard spacecraft are (a) Mass reduction and (b) A-I-T labour saving. Mass reduction would reduce cable mass and bulk, and simplify harness production. As the following figure shows, data harness accounts for more than half of the total harness weight. By adopting a wireless spacecraft bus, the amount of wires for data communication can be reduced, which would bring down the cost of the whole spacecraft mission. A-I-T is the process of assembling all of the components of the flight vehicle and verifying that the spacecraft operates correctly before launch The integration sequence is very tightly constrained and has to be meticulously planned Testing requires that data buses are probed, sensor/actuator interfaces are probed and excited, and all of this must be carried out in simulated space and launch environments The potential benefits of wireless interfaces during integration and test is extremely high  Currently, the test harness requirements introduce significant risks and cost impacts at a critical stage of spacecraft development A very strong financial case for the development of wireless technologies can be made on the potential benefits during integration and test . In the spacecraft business mass equals cost. Every kilogram of mass flown costs approximately $1 million. If the mass is reduced, the amount of fuel need to push would be reduced and the size of the launch vehicle need to lift the spacecraft is also reduced, which would bring down the cost of the whole mission. Thus it is our endeavour to propose a RF Based Intra-Spacecraft inter-network to harness data communication onboard a spacecraft.

Project Phases Completed:

1.0 PHASE I

1.1 Sounding Rocket Payload for June 2006 Launch
1.1.1 Design the preliminary wireless sounding rocket payload
1.1.2 Procure all necessary hardware and test equipment to support sounding rocket payload construction
1.1.3 Commission the initial phase of the wireless laboratory at ODU
1.1.4 Deliver sounding rocket experiment module, be ready for integration and space environmental testing

1.2 Orbital Payload Development
1.2.1 Identify candidate orbital flight experiments that have high value in terms of qualifying low-cost wireless systems that can be utilized for future spacecraft designs.
1.2.2 Develop proposals for at least two low-cost wireless orbital experiments (including the possible utilization of wireless systems to further instrument lower stage launch vehicle systems)

2.0 PHASE II

2.1 Wireless Laboratory Development
2.1.1. Procure the hardware and test equipment needed to build the core wireless laboratory at ODU
2.1.2. Implement the physical laboratory at ODU
2.1.3 Develop a proposal to MIST for the layout of the parallel wireless laboratory to be commissioned at the MIST facility in Pocomoke, MD

2.2 Wireless Spacecraft Environmental Simulation Facility
2.2.1 Develop a small spacecraft payload rack that is geometrically similar to actual spacecraft payload environment
2.2.2 Provide laboratory equipment that simulates electromagnetic radiation associated with the flight environment
2.2.3 Investigate effects of electromagnetic radiation on performance of wireless systems/protocols

2.3 MIST Wireless Sensor Network Laboratory, Pocomoke, MD
2.3.1 Designed the layout of the Wireless Sensor Laboratory in the MIST Pocomoke building
2.3.2 Establish education and training agreements with Eastern Shore educational institutions

Project Funding:

Mid Atlantic Institute for Space and Technology

Collaborators:

Salisbury University

University of Maryland Eastern Shore

Publication:

S. Shetty, Min Song, R. Ash, E. Ancel, and K. Bone, “Wireless sensor payload design for sounding rocket,” Proc. of the ISCA 22nd International Conference Computers and their Applications, March 2007.