The Inner Solar System Destinations of Explorer: An ESPA-Class Small Spacecraft

Abstract:

The Explorer is a small spacecraft designed for big science. This rideshare designed platform supports a wide range of self-contained missions with 12U inboard volume for payload / 8U outboard volume, 500W power generation at 1 AU from sun, > 1 kbps data downlink from 2 AU from Earth, 64 GB on-board data storage capacity, and in-space proven flight hardware and subsystems. The key capability of an Explorer ESPA-class payload is the Bradford ECAPS 22N high-thrust, high-performance green propulsion system, which enables the platform to reach its target destination when dropped off in a C3=0 Earth escape trajectory. The larger, 300 kg, Explorer relies on the Bradford Meteor propulsion system that has up to 5 km/s of delta-V. The concept of operations is to launch to low-Earth orbit as a secondary payload; commission the spacecraft and loiter until its injection window opens; and then perform its own Earth departure through a series of perigee kick maneuvers. In both cases, the platform allows for higher risk tolerance and relatively fast transfer orbit changes.

The ESPA-class Explorer can accommodate missions to the Moon, Venus, NEOs and main asteroid belt, and GEO Earth Observation. For example, Explorer is baselined as the platform of the Dark Ages Polarimetry Pathfinder (DAPPER) mission. The spacecraft will operate in a low lunar orbit above the farside and facilitate collection of 4615 hours of radio-quiet data over a 26.4-month lifetime. This paper presents the mission possibilities of this spacecraft as a low cost rideshare payload with the potential to achieve interplanetary missions at less than $50M, including launch.