The Ion Propulsion System for Dawn

Solar electric propulsion for future NASA missions

“…Building on the success of solar electric propulsion for NASA's Dawn [11] and JAXA's Hayabusa [12] missions, SEP has been analyzed for a number of missions [13,14,15], including Mercury missions, asteroid sample return, return of samples from the Martian moons Deimos and Phobos [16], and missions to the outer solar system [17,18]. Figure 4 shows one SEP spacecraft design study, the Diminutive Asteroid Visitor Using Ion Drive (DAVID) spacecraft, a small spacecraft designed to do a solar electric propulsion technology demonstration in an asteroid flyby mission [19,20].…”

Asteroid (4) Vesta II: Exploring a geologically and geochemically complex world with the Dawn Mission

“…Providing sufficient electrical energy to operate the electric ion propulsion system and to provide power to the other systems is a significant challenge for a solar-powered spacecraft operating at 3 AU. To provide the needed power, the spacecraft carries fixed on each side 5-panel solar "wings" that each measure 2.27 by 8.3 m. When fully extended, the two solar panels give the spacecraft an overall length of 19.73 m. The ion propulsion system (Brophy, 2011) operates by ionizing onboard xenon, which is then electrostatically accelerated to speeds as high as 40 km/s. Amazingly, the thruster produces a force of 18.8-91.0 mN, comparable to the force exerted by a single sheet of US letter or A4 paper pushing on the palm of your hand in Earth's gravity (∼50 mN).…”

An initial comparison of selected Earth departure options for solar electric propulsion missions

“…The Boeing 702 bus provides almost 4.5kWe input to the Electric Propulsion (EP) subsystem of Earth orbiting satellites for orbit raising and attitude control [13]. NASA Science Mission Directorate missions Deep Space -1 and Dawn both leverage EP to perform missions for significantly less cost than a similar chemical mission would due to the reduction in mass required for propulsion [14,15]. The Solar Electric Propulsion (SEP) element concept developed by the HEFT and HAT is a 300kW class vehicle engineered to be low cost and use as many off the shelf components as possible while still providing necessary performance.…”