The OSIRIS-REx Spacecraft and the Touch-and-Go Sample Acquisition Mechanism (TAGSAM)

Abstract

The Origins, Spectral-Interpretation, Resource-Identification, Security and Regolith-Explorer (OSIRIS-REx) spacecraft supports all aspects of the mission science objectives, from extensive remote sensing at the asteroid Bennu, to sample collection and return to Earth. In general, the success of planetary missions requires the collection, return, and analysis of data, which in turn depends on the successful operation of instruments and the host spacecraft. In the case of OSIRIS-REx, a sample-return mission, the spacecraft must also support the acquisition, safe stowage, and return of the sample. The target asteroid is Bennu, a B-class near-Earth asteroid roughly 500 m diameter. The Lockheed Martin-designed and developed OSIRIS-REx spacecraft draws significant heritage from previous missions and features the Touch-and-Go-Sample-Acquisition-Mechanism, or TAGSAM, to collect sample from the surface of Bennu. Lockheed Martin developed TAGSAM as a novel, simple way to collect samples on planetary bodies. During short contact with the asteroid surface, TAGSAM releases curation-grade nitrogen gas, mobilizing the surface regolith into a collection chamber. The contact surface of TAGSAM includes "contact pads", which are present to collect surface grains that have been subject to space weathering. Extensive 1-g laboratory testing, "reduced-gravity" testing (via parabolic flights on an airplane), and analysis demonstrate that TAGSAM will collect asteroid material in nominal conditions, and a variety of off-nominal conditions, such as the presence of large obstacles under the TAGSAM sampling head, or failure in the sampling gas firing. TAGSAM, and the spacecraft support of the instruments, are central to the success of the mission.

Craters, boulders and regolith of (101955) Bennu indicative of an old and dynamic surface

“…These locations may be reservoirs for smaller particles produced or exposed during the crater formation process, while boulder fracturing processes or abrasion/mechanical erosion between boulders could both contribute to the production of fine grains more widely across the surface of Bennu. The evidence for finegrained material (of the centimeter-scale sizes that are ingestible by the OSIRIS-REx sample mechanism [Bierhaus et al 2018] and of smaller, micron-scale sizes) is abundant despite not being resolved with current imaging. The measured thermal inertia suggests a substantial population of centimeter-sized particles (DellaGuistina and Emery et al 2019).…”

The OSIRIS-REx Thermal Emission Spectrometer (OTES) Instrument

“…Following the delivery of the Flight instrument to the spacecraft developer and flight system integrator, Lockheed Martin Space Systems (LMSS; Bierhaus et al 2017), three noise sources were observed during spacecraft testing. The first consisted of extremely high noise on the IR signal that occurred without any degradation in the servo performance.…”

OSIRIS-REx Contamination Control Strategy and Implementation

“…The OSIRIS-REx spacecraft will collect surface regolith via a touch-and-go sample acquisition mechanism (TAGSAM) that fluidizes loose particles with high-pressure, high-purity N 2 /He gas (Bierhaus et al 2017). The N 2 /He gas carries the samples into a cylindrical sample container, enclosed by biaxially oriented polyethylene terephthalate (e.g., Mylar®) flaps; 5% He is added for leak checking prior to launch.…”