In January 2017, Psyche and a second mission concept were selected by NASA for flight as part of the 14th Discovery mission competition. Assigned for an initial launch date in 2023, the Psyche team was given direction shortly after selection to research the possibility for earlier opportunities. Ultimately, the team was able to identify a launch opportunity in 2022 with a reduced flight time to its destination. This was accomplished in large part to crosscutting trades centered on the electrical power subsystem. These trades were facilitated through the Psyche mission's planned use of Solar Electric Propulsion (SEP), which enables substantial flexibility with respect to trajectory design. In combination with low-thrust trajectory analysis tools, the team was able to robustly converge to solutions with a higher fidelity and accuracy of results. These trades also took advantage of the 1300 series product line produced by Space Systems Loral (SSL), which enabled power growth while maintaining strong system-level heritage through its modular design that has been utilized on a large number of geostationary (GEO) communications satellites. This paper presents an overview of the Psyche mission concept, and the unique architecture that enables the use of commercially developed electric propulsion and space power systems from Space Systems Loral to provide flexibility in mission design. This paper then discusses the trades that allowed the Psyche team to meet a 2022 launch date.

COBALT (CoOperative Blending of Autonomous Landing Technologies) is a NASA technology development and test program to advance precision landing capabilities for future soft landers. The COBALT payload demonstrated terrain relative navigation utilizing the Lander Vision System and Navigation Doppler Lidar sensors on the Masten Space Systems Xodiac rocket. In spring 2017, the program culminated in two open-loop free flights to 500 m altitude with downrange diverts of 300 m. The COBALT system performed well, navigating within meters of the Xodiac vehicle's GPS-based solution. This paper outlines details of the navigation filter and its performance during the test campaign.

A terrestrial, open-loop (OL) flight test campaign of the NASA COBALT (CoOperative Blending of Autonomous Landing Technologies) platform was conducted onboard the Masten Xodiac suborbital rocket testbed, with support through the NASA Advanced Exploration Systems (AES), Game Changing Development (GCD), and Flight Opportunities (FO) Programs. The COBALT platform integrates NASA Guidance, Navigation and Control (GN&C) sensing technologies for autonomous, precise soft landing, including the Navigation Doppler Lidar (NDL) velocity and range sensor and the Lander Vision System (LVS) Terrain Relative Navigation (TRN) system. A specialized navigation filter running onboard COBALT fuzes the NDL and LVS data in real time to produce a precise navigation solution that is independent of the Global Positioning System (GPS) and suitable for future, autonomous planetary landing systems. The OL campaign tested COBALT as a passive payload, with COBALT data collection and filter execution, but with the Xodiac vehicle Guidance and Control (G&C) loops closed on a Masten GPS-based navigation solution. The OL test was performed as a risk reduction activity in preparation for an upcoming 2017 closed-loop (CL) flight campaign in which Xodiac G&C will act on the COBALT navigation solution and the GPS-based navigation will serve only as a backup monitor.

In September 2015, NASA selected five mission concepts from a field of 27 to proceed to the next stage (step 2) of the latest Discovery mission competition. Each team submitted a Mission Concept Study to NASA in August 2016, and in January of 2017 NASA selected Psyche and a second mission for flight. This paper describes Psyche, a unique investigation of a metal world, which is the only one of the original five mission concepts studied in detail to propose the use of Electric Propulsion (EP) to accomplish its mission objectives. Psyche will harness commercially developed EP and space power systems with strong system-level heritage to accomplish a deep space NASA science mission at comparatively low technical-risk and cost-risk. This paper describes the Psyche mission concept and the unique Solar Electric Propulsion (SEP) architecture that allows the use of SSL's commercial SPT-140 Hall thruster propulsion system at solar distances of up to 3.3 AU with only minimal modifications. Building on previous work analyzing SEP systems for Discovery-class missions, this paper describes the heritage, design, and testing which have been conducted on the power and propulsion systems to develop the Psyche mission, addresses the differences between GEO and deep-space environments, and describes actions taken to ensure that GEO heritage systems can be operated reliably in deep-space.

A rover occlusion is a part of the spacecraft which blocks the high-gain antenna's view of the Earth, interfering with communication. A flop is a change of kinematic solution in the middle of an Earth track, temporarily breaking the communications link. When the Mars Science Laboratory rover is level and the Earth is near the horizon, the Earth is occluded for 55 percent of rover headings. When the rover is level and the Earth is near zenith, a flop is required to continue tracking for 44 percent of rover headings. These constraints and two tools used in everyday tactical operations to help rover planners choose unoccluded, flop-free end-of-drive headings are described.

Of all the contributions to attitude and pointing error in the Curiosity rover on Mars, only those from clock drift and gyroscope propagation increase over time. A single update on sol 647 to the onboard model of planetary motion both corrected for accumulated clock drift error and compensated for future clock drift. A flight software update on sol 481 added an accelerometer-only mode for updating attitude, eliminating accumulation of gyroscope propagation error when updating attitude during arm activities. The adoption of an operational pattern of following each drive with an accelerometer-based correction to attitude eliminated the roll and pitch components of gyroscope propagation error accumulated during drives. With these three improvements, only the yaw component of gyroscope propagation error grows from sol to sol.

The spectacular landing of the Mars Science Laboratory "Curiosity" rover in August 2012 was made possible by the near perfect delivery of the vehicle to the planned entry conditions after a 8-month interplanetary cruise. Using a spin-stabilized attitude control architecture based on the earlier Mars Exploration Rovers and Mars Pathfinder missions, MSL executed 4 trajectory corrections, 22 turns to maintain power and communications and 18 turns in support of in-flight alignments and calibrations. To enable use of a guided, lifting entry, cruise ACS was also called on to perform a high-reliability precision initialization of the entry vehicle's onboard inertial navigation system just before landing. Along with other surprises, cruise operations were complicated by an early problem with the spacecraft flight computer which prevented use of the onboard star scanner for the first few months of flight. During this important period, ACS activities were accomplished using a combination of sun-only modes and ground based attitude determination. This paper outlines the MSL cruise attitude control system and relates our flight experience during operations, describing some of the challenges faced during the mission and the techniques and system features used to over-come them. We also present a performance assessment and several lessons learned with relevance. to Mars 2020 and other future missions using the MPF/MER/MSL cruise architecture.

The Deep Impact Spacecraft flew past Comet 103P/Hartley 2 on November 4th, 2010. Images revealed the comet to be enveloped in a field of debris composed of fine grained dust, ice, and hundreds of discrete millimeter to decimeter sized particles. In this work, a selection of the brightest particles are identified and photogrammetrically located in 3D space to examine their positions and dynamics. 90% of the particles detected were within 10 km of the nucleus and traveling a few meters per second or slower. The particles exhibit a high degree of temporal variability in brightness, suggesting rotating, heterogeneous and faceted geometries. This style of near-nucleus environment has not been observed in any other comet to date and it may help explain the hyperactive nature of water production on Hartley 2 and similar comets. (c) 2012 Elsevier Inc. All rights reserved.

We describe three methods for determination of the impact point of the Deep Impact Impactor on Comet 9P/Tempel 1, and the probable errors associated with each method. From this analysis it appears that the three methods give results that are consistent within their probable errors. (c) 2012 Elsevier Inc. All rights reserved.

Understanding how comets work--what drives their activity--is crucial to the use of comets in studying the early solar system. EPOXI (Extrasolar Planet Observation and Deep Impact Extended Investigation) flew past comet 103P/Hartley 2, one with an unusually small but very active nucleus, taking both images and spectra. Unlike large, relatively inactive nuclei, this nucleus is outgassing primarily because of CO(2), which drags chunks of ice out of the nucleus. It also shows substantial differences in the relative abundance of volatiles from various parts of the nucleus.

Returning a cold sample containing the ices from a cometary nucleus has long been an unachievable goal of cometary scientists. The results from the Deep Impact encounter with comet Tempel 1 suggest that the task is much easier than previously thought. Thus a cold sample return with ice becomes an achievable goal, at least from comet Tempel 1 and plausibly from other, active Jupiter-family comets.