Damon Landau

An initial comparison of selected Earth departure options for solar electric propulsion missions

Earth departure options such as the location for deployment, aggregation, and crew rendezvous as well as the type of propulsion leveraged for each mission phase effect overall mission performance metrics such as number of critical maneuvers, mass of propellant to achieve departure, and initial mass required in low Earth orbit. This paper identifies and compares a subset of tactical options for deployment, crew rendezvous, and Earth departure that leverage electric propulsion and hybrid chemical electric propulsion with a goal of improving system efficiency. Departure maneuver specific limitations and penalties are then identified for missions to specific targets for human interplanetary missions providing a better understanding of the impact of decisions related to aggregation and rendezvous locations as well as Earth departure maneuvers on overall system performance.

Human cargo resupply logistics at mars using 150kW SEP tug cyclers

The ultimate goal of the Evolvable Mars Campaign is to build up a sustainable outpost at Mars that would be continually staffed with rotating crews. During this stage of human Mars exploration, it would be necessary to provision the crews with equipment and supplies both before and during their missions. In this paper, we study the use of 150 kW reusable SEP tugs as a means to deliver elements both to orbit and to the surface. The SEP tugs would make use of technology currently being developed for the proposed Asteroid Robotic Redirect Mission (ARRM). They would also be used to deliver food and supplies to sustain the crews similar to resupply missions for the International Space Station. The SEP tugs envisioned would be staged at a quasi-stable Lunar Near Rectilinear Orbit (NRO). The tugs would then mate with cargo vessels and xenon propellant being delivered by an SLS launch vehicle and continue on to Mars orbit where the cargo is delivered and the SEP tug returns to NRO to repeat the process. It was found that it is more efficient to deliver surface cargo via direct launch and entry versus using the tug cycler. Thousands of optimized low-thrust trajectories were simulated in order to create “Bacon plots” (like porkchop plots, but for low thrust transfers) in order to map out potential trajectories for dates from 2039 to 2052. This study maps out the buildup of a surface outpost as well as the necessary orbital and surface resupply launches in order to maintain it. In the steady state, a cadence of 9 cargo launches is required every 4 years to sustain the human outpost.

Psyche: Journey to a metal world

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 SSLs 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.

Defining the requirements for the Micro Electric Propulsion systems for small spacecraft missions

Recent technology advancements in Micro Electric Propulsion (MEP) will enable the next generation of small spacecraft to perform trajectory and attitude maneuvers with significant ΔV requirements, provide thrust over long mission durations, and replace reaction wheels for attitude control. These advancements will open up the class of mission architectures achievable by small spacecraft to include formation flying, proximity operations, and precision pointing missions in both LEO and interplanetary destinations. The goal of this study is to establish the optimal performance parameters for future MEP technology that are applicable to a broad range of flight demonstration platforms (e.g. dedicated 3-12U CubeSats to ESPA-class spacecraft ), for a variety of applications, including LEO and Earth escape orbit transfers, travel to interplanetary destinations, hover and drag make-up missions, and performing reaction wheel-free attitude control. An integrated systems-level model for propulsion, spacecraft (power, data, telecommunication, thermal management), and orbit and attitude maneuvers is developed to support solution space exploration. MEP system performance parameters are derived that maximize the performance capability subject to realistic system-level constraints in the context of upcoming mission opportunities where MEP is enabling or advantageous relative to other technologies.