Engineering topics

Beshore, E.

Publications and source records attributed to Beshore, E..

6 records

NASA NTRS2018

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

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.

Spacecraft↗

NASA NTRS2017

OSIRIS-REx Contamination Control Strategy and Implementation

OSIRIS-REx will return pristine samples of carbonaceous asteroid Bennu. This article describes how pristine was defined based on expectations of Bennu and on a realistic understanding of what is achievable with a constrained schedule and budget, and how that definition flowed to requirements and implementation. To return a pristine sample, the OSIRIS-REx spacecraft sampling hardware was maintained at level 100 A/2 and less than 180 ng/cm(exp 2) of amino acids and hydrazine on the sampler head through precision cleaning, control of materials, and vigilance. Contamination is further characterized via witness material exposed to the spacecraft assembly and testing environment as well as in space. This characterization provided knowledge of the expected background and will be used in conjunction with archived spacecraft components for comparison with the samples when they are delivered to Earth for analysis. Most of all, the cleanliness of the OSIRIS-REx spacecraft was achieved through communication among scientists, engineers, managers, and technicians.

OSIRIS-RE↗

NASA NTRS2017

OSIRIS-REx Contamination Control Strategy and Implementation

OSIRIS-REx will return pristine samples of carbonaceous asteroid Bennu. This manuscript describes how pristine was defined based on expectations of Bennu and on a realistic understanding of what is achievable with a constrained schedule and budget, and how that definition flowed to requirements and implementation. To return a pristine sample, the OSIRIS-REx spacecraft sampling hardware was maintained at Level 100 A/2 and less than 180 nanograms per square centimeter of amino acids and hydrazine on the sampler head through precision cleaning, control of materials, and vigilance. Contamination is further characterized via witness material exposed to the spacecraft assembly and testing environment as well as in space. This characterization provided knowledge of the expected background and will be used in conjunction with archived spacecraft components for comparison with the samples when they are delivered to Earth for analysis. Most of all, the cleanliness of the OSIRIS-REx spacecraft was achieved through communication between scientists, engineers, managers, and technicians.

Dworkin, J. P.↗

NASA NTRS2015

The OSIRIS-REx Contamination Control and Witness Strategy

The OSIRIS-REx mission (Origins, Spectral Interpretation, Resource Identification, and Security Regolith Explorer) is the third NASA New Frontiers mission. It is scheduled for launch in 2016. The primary objective of the mission is to return at least 60 g of "pristine" material from the B-type near- Earth asteroid (101955) Bennu, which is spectrally similar to organic-rich CI or CM meteorites [1]. The study of these samples will advance our understanding of materials available for the origin of life on Earth or elsewhere. The spacecraft will rendezvous with Bennu in 2018 and spend at least a year characterizing the asteroid before executing a maneuver to recover a sample of regolith in the touch-and-go sample acquisition mechanism (TAGSAM). The TAGSAM and sample is stowed in the sample return capsule (SRC) and returned to Earth in 2023.

New Frontiers mission↗

NASA NTRS1980

Imaging photopolarimeter on Pioneer Saturn

Results of Pioneer 11 imaging photopolarimeter observations of Saturn, its rings, and Titan are presented. The imaging photopolarimeter is a pointable telescope with an aperture of 2.5 cm and passbands of 390 to 500 to 720 nm which uses the spin of the spacecraft to scan across an object. Images of the Saturn system and of the rings are presented, and the absence of a D ring, structures in the C, B and A rings and the Cassini division and the discoveries of the F ring and the provisionally named Pioneer division separating it from the A ring are reported. A mean particle size less than 15 meters is estimated from estimates of total ring mass and the optical depth of the B ring. The discovery of the satellite 1979 S 1 at 2.53 Saturn radii is also noted. Models of the vertical aerosol structure of Saturn's atmosphere are compared with the polarization data, and it is indicated that the density of cloud particles decreases with altitude with a scale height about one fourth that of the gas, and that an optical depth of one is to be found at 750 mbar.

Gehrels, T.↗

NASA NTRS1975

The imaging photopolarimeter experiment on Pioneer 11

For 2 weeks continuous imaging, photometry, and polarimetry observations were made of Jupiter and the Galilean satellites in red and blue light from Pioneer 11. Measurements of Jupiter's north and south polar regions were possible because the spacecraft trajectory was highly inclined to the planet's equatorial plane. One of the highest resolution images obtained is presented here along with a comparison of a sample of our photometric and polarimetric data with a simple model. The data seem consistent with increased molecular scattering at high latitudes.

Baker, A. L.↗