Small Satellite Missions to Deep Space Enabled by Solar Thermal Rockets

Solar thermal rockets (STR) were examined to determine how well they could integrate with small satellite systems to propel very small payloads to the outer reaches of the Solar System. The spacecraft would use an STR to achieve hyperbolic velocity while in the vicinity of Earth. A set of calculations estimated the distance from the Sun and flight time of a flyby mission launched from small launch vehicles such as the Pegasus, Taurus and Delta 6920. Rendezvous missions were modeled using solar photovoltaic or radio isotope thermoelectric generators with electric propulsion to make the spacecraft velocity match that of the target object. The Pegasus would send 10 to 25 kg sensor payloads to fly by objects near the ecliptic out as far as Saturn. It could also send a 10 kg payload to rendezvous with most of the known Near Earth Objects (NEOs). The Taurus could send these payloads to fly by Pluto. It could also achieve rather fast, 1.5 year flyby of Jupiter, and less than 3 years to Saturn. The Delta could rendezvous with Pluto on a 20 year mission. It could rendezvous in less than about 15 years by staging. The STR provides a 16 square meter mirror that can be used as a form of telescope, giving it dual-use as a sensor element. The general conclusion was that high performance STR enables small satellite systems to achieve high delta V, 15,000 m/s missions not practical with chemical systems. These include fast, 1 year direct missions to fly by Jupiter and most of the objects closer than Jupiter, which include most of the known NEOs. The STR also enables small satellite rendezvous with most of the N EOs and fly by with Pluto. With the help of RTG class electric power generators, small satellite systems can achieve rendezvous with Pluto, and hence everything closer.