Spacecraft

As a Discovery Program mission, Dawn combined innovative state-of-the-art technologies pioneered by other recent missions with off-the-shelf components and, in some cases, spare parts and instrumentation left over from previous missions.

Structure

A labeled diagram of the Dawn spaccraft.

With its wide solar arrays extended, Dawn is about as long as a tractor-trailer at 65 feet (19.7 meters). The ion thruster is powered by large solar panels. The power ionizes the fuel (Xenon) and then accelerates it with an electric field between two grids. Electrons are injected into the beam after acceleration to maintain a neutral plasma.

Spacecraft Statistics

Dimensions: 5.4 feet (1.64 meters) long, 4.2 feet (1.27 meters) wide and 5.8 feet (1.77 meters) high. High-gain antenna is 5 feet (1.52 meters) in diameter. Solar array is 65 feet (20 meters) long, tip to tip
Spacecraft weight: 1,647.1 pounds (747.1 kilograms)
Propellant at launch: 937 pounds (425 kilograms) xenon propellant for the ion propulsion system
Estimated propellant remaining*: 31 pounds (14 kg)
Pointing control at launch: four reaction wheels, augmented by 100.5 pounds (45.6 kilograms) of hydrazine
Pointing control at end of mission*: hydrazine only, fuel ran out on Oct. 31, 2018.
Power: Two 27-foot-by-8-foot (8.3-meter-by-2.3-meter) solar arrays, together providing more than 10 kilowatts at Earth’s distance from the Sun and 1.4 kilowatts at Dawn’s (and Ceres’) maximum distance from the Sun. Each wing-like array weighs almost 139 pounds (63 kilograms). Energy storage via 35-amp-hour rechargeable nickel hydrogen battery

Ion Propulsion System

Number of thrusters: 3
Thruster dimensions (each): 13 inches (33 centimeters) long, 16 inches (41 centimeters) in diameter
Weight: 20 pounds (8.9 kilograms) each
Spacecraft acceleration via ion propulsion at full thrust: 0 – 60 mph in 4 days
Thrust: 0.07 to 0.33 ounce (19 to 91 millinewtons)

Type: Orbiter

Status: Success—Mission Completed

Launch Date: Sept. 27, 2007 | 11:34 UTC

Launch Location: Cape Canaveral Air Force Station, Florida

Targets: Vesta and Ceres

Destination: Vesta and Ceres

Mission Events

Sept. 27, 2007: Launch
Feb. 17, 2009: Mars Gravity Assist
July 16, 2011: Vesta Arrival
Sept. 5, 2017: Vesta Departure
March 5, 2015: Ceres Arrival
June 2016: End of prime mission
July 2016: Start of first extended mission
October 2017: Start of second extended mission
Nov. 1, 2018: End of Mission