Abstract
Is it possible to offer sub metre imaging from a small satellite, in this case defined as having a total mass under 500 kg, while still staying within the boundaries of a ‘low cost space mission’? If so, can a constellation of such spacecraft offer an operationally unbeatable combination of imaging resolution, area coverage and timeliness for less than the cost of a single, large, high resolution spacecraft? Government and a growing number of commercial customers have recognised the utility and price-performance benefits of small spacecraft. Sub-1m imaging opens up a huge range of applications to the user of Earth Observation (EO) data, however targeting improved imaging payload resolution does not make a system more useful, unless a number of other parameters are improved. The paper firstly summarises the options for building a sub-metre resolution camera in a low cost, small satellite mission context, since this is currently the metric used to compare small satellites against the state-of-the-art. An analysis is then presented of the complex trade-offs between orbit height, image resolution & quality, lifetime, and spacecraft configuration. This initial trade-off is required to identify the most appropriate operational altitudes associated with different orbit maintenance strategies. A comparison is made with other high resolution commercial EO missions. The paper will cover the engineering challenges of flying a sophisticated optical bench into orbit, considering in particular the propulsion, structure, thermal and Attitude control; and the modes of operation that can be supported with a spacecraft designed to deliver very high resolution from orbit. Some of the trade-offs associated with detector design will also be addressed, including the potential need for active attitude control during imaging to control the read-out rate required from the sensor. The paper concludes with a short section on the estimated performance of a constellation of small, low cost very high resolution imaging spacecraft, which has the potential to offer an operationally unbeatable combination of imaging resolution, area coverage and timeliness for less than the cost of a single, large, high resolution spacecraft.
Presentation Slides
Reading the Fine print from Orbit: Its Not Just about the Resolution
Is it possible to offer sub metre imaging from a small satellite, in this case defined as having a total mass under 500 kg, while still staying within the boundaries of a ‘low cost space mission’? If so, can a constellation of such spacecraft offer an operationally unbeatable combination of imaging resolution, area coverage and timeliness for less than the cost of a single, large, high resolution spacecraft? Government and a growing number of commercial customers have recognised the utility and price-performance benefits of small spacecraft. Sub-1m imaging opens up a huge range of applications to the user of Earth Observation (EO) data, however targeting improved imaging payload resolution does not make a system more useful, unless a number of other parameters are improved. The paper firstly summarises the options for building a sub-metre resolution camera in a low cost, small satellite mission context, since this is currently the metric used to compare small satellites against the state-of-the-art. An analysis is then presented of the complex trade-offs between orbit height, image resolution & quality, lifetime, and spacecraft configuration. This initial trade-off is required to identify the most appropriate operational altitudes associated with different orbit maintenance strategies. A comparison is made with other high resolution commercial EO missions. The paper will cover the engineering challenges of flying a sophisticated optical bench into orbit, considering in particular the propulsion, structure, thermal and Attitude control; and the modes of operation that can be supported with a spacecraft designed to deliver very high resolution from orbit. Some of the trade-offs associated with detector design will also be addressed, including the potential need for active attitude control during imaging to control the read-out rate required from the sensor. The paper concludes with a short section on the estimated performance of a constellation of small, low cost very high resolution imaging spacecraft, which has the potential to offer an operationally unbeatable combination of imaging resolution, area coverage and timeliness for less than the cost of a single, large, high resolution spacecraft.
