OSIRIS-REx
==========

The Origins Spectral Interpretation Resource Identification Security-Regolith Explorer (OSIRIS-REx) spacecraft is a derivative of the Mars Reconnaissance Orbiter (MRO) and Mars Atmosphere and Volatile EvolutioN (MAVEN) spacecraft, leveraging the key heritage design components of these two missions. Healthy resource margins across the vehicle, fully redundant spacecraft sub-systems with extensive cross strapping, and high heritage hardware enable flexibility throughout the spacecraft development and during flight operations [SKEENETAL2015] Telecommunications Subsystem ---------------------------- The telecom subsystem utilizes X-band communications, using a MAVEN build-to-print high gain antenna and MRO heritage traveling wave tube amplifier for science high data rate downlink. A medium gain antenna is utilized during the TAG mission phase. Also two low gain antennas are available for TAG but also used for nominal (and safe-mode) engineering data downlink and uplink commanding [SKEENETAL2015]. Guidance, Navigation and Control (GNC) ------------------------------------------- The GNC subsystem includes four reaction wheel assemblies (RWAs) for performing spacecraft slewing and low jitter pointing during science operations. These reaction wheels also store system momentum between desaturation events. The GNC subsystem is responsible for commanding all of the thrusters on the spacecraft including executing trajectory correction maneuvers and RWA desats. The GNC subsystem utilizes an inertial measurement unit (IMU) and flight-proven star trackers to deter-mine and propagate on-board attitude knowledge. Sun sensors additionally support spacecraft autonomous safing operations. Two GNC sensors provide measurements used for relative navigation: a GNC LIDAR is used for ranging to the surface to support TAG operations, and a TAG camera system (TAGCAMS) supports ground based navigation throughout proximity operations and autonomous on-board optical based navigation during the TAG phase [SKEENETAL2015]. Propulsion Subsystem -------------------- The high heritage propulsion subsystem is a single fault tolerant monopropellant system. The propulsion subsystem includes main engines, trajectory correction maneuver thrusters, attitude control system thrusters, and low thrust reaction engine assemblies [SKEENETAL2015]. Power Subsystem --------------- The power subsystem includes two rigid solar arrays, gimbaled about the spacecraft Y and Z axes. In addition, two batteries are utilized for off-sun maneuvering, including the critical TAG mission phase [SKEENETAL2015]. TAGSAM --------------------- The TAGSAM is the key flight system component, used for making contact and acquiring sample from the surface of Bennu during the TAG mission phase. TAGSAM is designed to collect greater than 150 g to provide margin to the 60 g mission requirement. The TAGSAM functions by fluidizing regolith with high pressure gaseous nitrogen flow to transport it to a sample container located in the TAGSAM ‘head’. The TAGSAM is made up of a single planar, articulating arm with redundant motor windings at the shoulder, elbow, and wrist and provides large structural, torque, and alignment margins, ultimately ensuring successful sample acquisition and stowage of the TAGSAM head into the SRC [SKEENETAL2015]. Sample Return Capsule (SRC) ------------ To safely return the collected sample to Earth, OSIRIS-Rex capitalizes on the success of NASA’s Stardust mission. The proven Stardust SRC technology and capsule, mission operations, and mission de-sign are all reused on OSIRIS-Rex for Bennu sample return [SKEENETAL2015]. Science Sensors --------------- The OSIRIS-REx Spacecraft is host to the following scientific instruments that are used to characterize the surface of asteroid Bennu for sample-site selection and for longer term scientific analysis: (1) OSIRIS-REX Camera Suite (OCAMS) (2) OSIRIS-REx Laser Altimeter (OLA) (3) OSIRIS-REx Thermal Emission Spectrometer (OTES) (4) OSIRIS-REx Visible and Near Infrared Spectrometer (OVIRS) (5) Regolith X-Ray Imaging Spectrometer (REXIS) Radio Science investigations are carried out using the on-board and ground elements of the Telecommunications Subsystem. More information on instrumentation for each of the science investigations can be found elsewhere. \