Robert Shotwell

Drivers, developments and options under consideration for a Mars ascent vehicle

The NASA Mars Exploration Program has invested technology funds over the last couple of years to advance design concepts for a Mars Ascent Vehicle (MAV) and technologies that may be enhancing or enabling for various architectures to be pursued. A Mars Ascent Vehicle would fly on a potential future Mars Lander mission to recover and return the samples to be acquired by the Mars 2020 rover, or another future mission, to a retrievable orbit. Resembling a terrestrial Surface to Air Missile (SAM), the propulsion options considered for the MAV concept span the range from two stage solid rocket motors to monoprops, biprops and hybrids. This paper will highlight the driving constraints and performance requirements and the subsequent trades that would ultimately drive the selection of a chosen approach.

A Hybrid Mars Ascent Vehicle Concept for Low Temperature Storage and Operation

A hybrid propulsion system presents many advantages for a potential Mars Ascent Vehicle including high specific impulse, restartability and predicted excellent low temperature survivability. This additional benefit of low temperature storage and operation could substantially reduce the power required to maintain the system while on Mars and therefore decrease the total landed system mass required for the system. A new wax-based hybrid fuel has been formulated to realize these low temperature benefits, while still preserving high performance (Isp). The freezing point of the oxidizer can be selected to match the capabilities of the fuel, in this case Mixed Oxides of Nitrogen has been selected. The main disadvantages of this system are associated with the relatively low technology readiness level of the selected hybrid propulsion system for operation on Mars. However, technology development efforts are currently underway to advance the hybrid propulsion system to a level where it could potentially compete with heritage propulsion systems. An internal study completed at JPL in 2015 identified the single stage to orbit hybrid MAV as the lowest gross liftoff mass case from a large range of potential propulsion systems. Updates to this design are presented here.

Rapid Mission Architecture trade study of Enceladus mission concepts

At the request of the Satellites Panel of the National Research Council (NRC) Planetary Science Decadal Survey, a Rapid Mission Architecture (RMA) study of possible missions to Saturns moon Enceladus was conducted at the Jet Propulsion Laboratory in January and February of 2010. This was one of many studies commissioned by this NRC Decadal Survey. In this study, 15 Enceladus mission architectures were examined that spanned a broad range of potential science return and total estimated mission cost.

Technology development and design of a hybrid Mars ascent vehicle concept

Hybrid propulsion has been investigated as an enhancing technology for a Mars Ascent Vehicle (MAV) concept as part of potential Mars Sample Return (MSR) because of its high specific impulse, restartability, and the ability to operate and survive at extremely low temperatures. A new wax-based hybrid fuel formulation has been developed that could withstand the harsh and variable Mars environment protected solely by a minimal layer of passive insulation. This formulation could provide substantial energy savings for a notional lander and is critical for rover mobility. Preliminary thermal cycle testing has determined that the formulation can survive the expected temperature extremes and lifetime thermal testing is currently underway. A complete preliminary design using this new fuel formulation combined with a low temperature oxidizer such as Mixed Oxides of Nitrogen (MON30) is presented. Several key features associated with a complete hybrid MAV concept are investigated to determine their mission suitability (e.g. Thrust Vector Control and restartable ignition options). Potential challenges along a path towards developing such a system are outlined and future work is suggested as a means of technology maturation. The hybrid design presented here was the lowest Gross Lift Off Mass (GLOM) result of a 2015 Jet Propulsion Laboratory (JPL) led MAV concept study [1].

Phoenix - The First Mars Scout Mission

As the first of the new Mars Scouts missions, the Phoenix project was selected by NASA in August of 2003. Four years later, almost to the day, Phoenix was launched from Cape Canaveral Air Station and successfully injected into an interplanetary trajectory on its way to Mars. On May 25, 2008 Phoenix conducted the first successful powered decent on Mars in over 30 years. This paper will highlight some of the key changes since the 2008 IEEE paper of the same name, as well as performance through cruise, landing at the north pole of Mars and some of the preliminary results of the surface mission.

A P-band radar mission to Mars

Large regions of Mars are covered by dust that obscures geological evidence for fluvial channels, the extent of volcanic flows, and features associated with near-surface ground ice. We describe a Mars orbiting mission carrying a P-band SAR to map these hidden surface features. Mapping would be carried out in HH and VV polarizations, with the comparison of the two expected to yield a distinction between surface echoes and subsurface features beneath up to 5 m of dust. Repeat-pass interferometry data would also be collected to characterize volatile migration at the poles, aeolian shifting of the dust mantle, and possible volcanic deformation. This work describes the technical design of a P-band SAR for global mapping of Mars, and the characteristics of the proposed mission.

A Mars Ascent Vehicle for potential mars sample return

This paper will cover the conceptual design of a Mars Ascent Vehicle (MAV) and efforts underway to raise the TRL at both the component and system levels. A system down select was executed resulting in a Hybrid Propulsion based Single Stage To Orbit (SSTO) MAV baseline architecture. This paper covers the Point of Departure design, as well as results of hardware developments that will be tested in several upcoming flight opportunities.

A hybrid mars ascent vehicle design and FY 2016 technology development

Hybrid propulsion is currently favored for a Mars Ascent Vehicle (MAV) concept from a thermal performance and Gross Lift Off Mass standpoint. However, it is at a relatively low level of maturity compared to conventional propulsion options. Technology development efforts are currently underway to bring hybrid propulsion to a technology readiness level that would enable its infusion into potential Mars Sample Return. A new propellant combination is being considered for this design that has excellent low temperature behavior. Preliminary results of two ground test campaigns are currently underway to characterize this propellant combination. Hotfire testing is being carried out in parallel at Parabilis Space Technologies and Space Propulsion Group. In addition to the new propellant combination, several other technologies are being pursued for a potential hybrid MAV: hypergolic ignition and Liquid Injection Thrust Vector Control. Both of these technologies have been applied in other rocket applications, e.g. liquid propulsion commonly uses hypergolic propellants and missiles, such as the Minuteman II, have used LITVC in the past. Hypergolic ignition, when oxidizer and fuel combust upon contact, is highly desirable for multiple starts required by the MAV concept. Therefore, testing at Penn State and Purdue is being completed in this area. An updated hybrid propulsion system design for a Mars Ascent Vehicle concept based on JPLs current understanding of potential Mars Sample Return requirements will be presented, leveraging the advances in technology development as well as updated understanding of how requirements may evolve.

Hybrid propulsion Mars Ascent Vehicle concept flight performance analysis

A high-fidelity simulation of a conceptual Mars Ascent Vehicle has been developed for end-to-end performance evaluation. The simulation environment is the Dynamics Simulator for Entry, Descent and Surface landing (DSENDS). The simulation work includes the modeling of the multi-body components, Martian environment, flight software and mission timeline. Using this simulation environment, the end-to-end MAV flight performance is evaluated, both in the nominal scenario and in perturbed off-nominal scenarios where model uncertainties are taken into account.

History of Mars Ascent Vehicle development over the last 20 years

The Mars Ascent Vehicle concept has seen many studies and development efforts over the last 20 years, up to efforts currently underway by the Mars Program Office. A wide range of concepts have been explored, and many participants over time have been involved. This paper will give an overview of this colorful history, including the context for the individual efforts, the people and organizations involved, and some details of various MAV concepts that have been considered.