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The Mars Interior Exploration using Seismic Investigations, Geodesy and Heat Transport (InSight) spacecraft, which successfully touched down on the planet surface on November 26, 2018, was proposed...

The Origins, Spectral Interpretation, Resource Identification, and Security–Regolith Explorer (OSIRIS-REx) spacecraft launched on September 8, 2016, beginning a seven-year journey to return at least 60 g of asteroid material from (101955) Bennu to Earth. During the outbound cruise, Doppler tracking of the spacecraft observed a small but measurable acceleration when the sample return capsule (SRC) was first placed in sunlight. Subsequent analysis determined that outgassing from the SRC is the most likely cause for the acceleration. This outgassing received combined engineering and scientific attention because it has potential implications both for spacecraft navigation performance and for contamination of the collected samples. Thermal modeling, laboratory studies of SRC materials, and monitoring of the acceleration are all consistent with H2O as the main component of the outgassing. Dedicated, in-flight campaigns continued to expose the SRC to sunlight until the acceleration dropped to the acceleration noise floor. Any residual amounts of H2O outgassing are not considered to be a hazard with regards to mission operations or pristine sample acquisition. The sample stow procedure has been updated to ensure that no direct line of site exists between any residual outgassing and the samples during future operations. Similar outgassing of the Stardust SRC probably also occurred. No adverse contamination of Stardust samples was observed that could be associated with this process. Future missions that use similar reentry vehicles should consider procedures to test for and, if necessary, mediate such outgassing after launch.

The Origins, Spectral Interpretation, Resource Identification, and Security–Regolith Explorer (OSIRIS-REx) mission will collect material from the asteroid Bennu and return it to Earth. The sample collection method uses pressurized nitrogen gas to mobilize regolith. It is likely that the gas will mobilize more, potentially much more, material than is captured by the Touch-and-Go Sample Acquisition Mechanism (TAGSAM) for return. The amount, velocities, and fate of this mobilized material have important implications for our understanding of Bennu's physical properties and processes, such as impact cratering, regolith mobility, and the recently observed natural ejection of particles. The nature of the TAGSAM-ejected material is also significant for mission operations. We conducted numerical simulations and ground-based tests to estimate the amount and speeds of material mobilized by the sampling event. The estimated ejected masses range from 12 kg to >165 kg; given that Bennu appears to be a nearly strengthless rubble pile, the higher end of the mass range is more likely. Maximum ejection speeds for 1-cm-diameter particles could reach 10 m/s; smaller particles will be ejected at faster speeds. Minimum ejection speeds will be determined by the as yet unknown cohesive strength of Bennu's regolith. Material ejected more slowly than 10 cm/s will reaccrete on Bennu; material ejected between 10 and 30 cm/s may or may not reaccrete; and material ejected faster than 30 cm/s will escape. Some of the ejected material is predicted to remain in transient orbits around Bennu. The lifetimes of these orbits span from days to several weeks, the maximum duration of our integrations. Reaccreted material should be concentrated in a region near the sample site, although re-impacts will occur globally. Gas from TAGSAM will mobilize material beyond the contact perimeter; because of interactions between cohesion and microgravity, there is a preferred particle size of mobility, predicted to be tens of centimeters, depending on the TAG latitude. Observing Bennu during and after the sampling event will make it possible to test these predictions and understand how the asteroid responds to disruption and particle mobility across the surface.

Thermal protection system materials for the Mars Science Laboratory mission were tested in the NASA Ames 60 MW arcjet in a shear environment. Shear tests were performed on candidate ablative heat shield materials in wedge and swept cylinder test fixtures. In portions of the expected flight environment, the proposed main heat shield material, known as SLA-561V, recessed orders of magnitude faster than predicted. An alternate main heat shield material, known as phenolic impregnated carbon ablator, behaved reasonably well in all regions of the flight envelope investigated here. However, the measured recession rate of the phenolic impregnated carbon ablator was on average 50% greater than the predicted recession by the fully implicit ablation and thermal response code, and in some cases the measured recession was as much as 150% greater (uncertainties included). Phenolic impregnated carbon ablator’s higher recession rate than predicted (in shear) resulted in adding thickness margin to the flight heat shield d...

[Abstract] Aerothermal analyses of the Phoenix entry vehicle in the Martian Atmosphere are presented. Two Navier-Stokes flow solvers are used to predict the environments experienced by the vehicle along several design trajectories. The majority of the solutions are computed as axisymmetric in order to yield higher, and therefore more conservative, heating rates. Several three-dimensional cases are also computed to assess the heating enhancement caused by surface singularities and the complex aftbody vortices. When the thermal protection system was assessed in a separate analysis in response to the computed aeroheating environments, the prebuilt design is found perform successfully.