Loc C. Huynh

Adaptive Deployable Entry and Placement Technology (ADEPT): A Feasibility Study for Human Missions to Mars

The present paper describes an innovative, semi-rigid, mechanically deployable hypersonic decelerator system for human missions to Mars. The approach taken in the present work builds upon previous architecture studies performed at NASA, and uses those findings as the foundation to perform analysis and trade studies. The broad objectives of the present work are: (i) to assess the viability of the concept for a heavy mass (landed mass ≈40 mT) Mars mission through system architecture studies; (ii) to contrast it with system studies previously performed by NASA; and (iii) to make the case for a Transformable Entry System Technology. The mechanically deployable concept at the heart of the proposed transformable architecture is akin to an umbrella, which in a stowed configuration meets launch requirements by conforming to the payload envelope in the launch shroud, and when deployed in earth orbit forms a large aerosurface designed to provide the necessary aerodynamic forces upon entry into the Martian atmosphere. The aerosurface is a thin skin draped over high-strength ribs; the thin skin or fabric with flexible material serves as the thermal protection system, and the ribs serve as the structure. A four-bar linkage mechanism allows for a reorientation of the aerosurface during aerocapture or during the entry and descent phases of atmospheric flight, thus providing a capability to navigate and control the vehicle and make possible precision landing. The actuators and mechanisms that are used to deploy the aerosurface are multi-functional in that they also allow for reorienting the

Mars Sample Return using commercial capabilities: Propulsive Entry, Descent, and Landing

This paper describes a critical portion of the work that has been done at NASA, Ames Research Center regarding the use of the commercially developed Dragon capsule as a delivery vehicle for the elements of a high priority Mars Sample Return mission. The objective of the investigation was to determine entry and landed mass capabilities that cover anticipated mission conditions. The “Red Dragon” Mars configuration uses supersonic retro-propulsion, with no required parachute system, to perform Entry, Descent, and Landing (EDL) maneuvers. The propulsive system proposed for use is the same system that will perform an abort, if necessary, for a human rated version of the Dragon capsule. Standard trajectory analysis tools are applied to publically available information about Dragon and other legacy capsule forms in order to perform the investigation. Trajectory simulation parameters include entry velocity, flight path angle, lift to drag Ratio (L/D), landing site elevation, atmosphere density, and total entry mass. In addition, engineering assumptions for the performance of the propulsion system are stated. Mass estimates for major elements of the overall proposed architecture are coupled to this EDL analysis to close the overall architecture. Three, Type 1 synodic launch opportunities, beginning with the 2022 opportunity, define the arrival conditions. Results are given for a system reflecting a nominal baseline set of the analysis parameters as well as sensitivities to those parameters. The EDL performance envelope includes landing altitudes between 0 and -4 km referenced to the Mars Orbiter Laser Altimeter datum as well as minimum and maximum atmosphere density. Total entry masses between 7 and 10 mt are considered with architecture closure occurring between 9.0 and 10 mt. Propellant mass fractions for each major phase of the EDL - Entry, Terminal Descent, and Hazard Avoidance - have been derived. A useful payload mass of 2.0 mt is provided and includes mass and growth allowance for a Mars Ascent Vehicle (MAV), Earth Return Vehicle (ERV), and mission unique equipment. The useful payload supports an architecture that receives a sample from another surface asset and sends it directly back to Earth for recovery in a high Earth orbit. The work shows that emerging commercial capabilities as well as previously studied EDL methodologies can be used to efficiently support an important planetary science objective. The work has applications for human exploration missions that will also use propulsive EDL techniques.

Mars Sample Return using commercial capabilities: Mission architecture overview

Mars Sample Return (MSR) is the highest priority science mission for the next decade as recommended by the recent Decadal Survey of Planetary Science. This paper presents an overview of a feasibility study for a MSR mission. The objective of the study was to determine whether emerging commercial capabilities can be used to reduce the number of mission systems and launches required to return the samples, with the goal of reducing mission cost. The major element required for the MSR mission are described and include an integration of the emerging commercial capabilities with small spacecraft design techniques; new utilizations of traditional aerospace technologies; and recent technological developments. We report the feasibility of a complete and closed MSR mission design using the following scenario that can start in any one of three Earth to Mars launch opportunities, beginning in 2022: A Falcon Heavy injects a SpaceX Red Dragon capsule and trunk onto a Trans Mars Injection (TMI) trajectory. The capsule is modified to carry all the hardware needed to return samples collected on Mars including a Mars Ascent Vehicle (MAV); an Earth Return Vehicle (ERV); and hardware to transfer a sample collected in a previously landed rover mission, such as the Mars 2020 rover, to the ERV. The Red Dragon descends to land on the surface of Mars using Supersonic Retro Propulsion (SRP). After previously collected samples are transferred to the ERV, the single-stage MA V launches the ERV from the surface of Mars to a Mars phasing orbit. The MA V uses a storable liquid, pump-fed bi-propellant propulsion system. After a brief phasing period, the ERV, which also uses a storable bi-propellant system, performs a Trans Earth Injection (TEl) burn. Once near Earth the ERV performs Earth and lunar swing-bys and is placed into a Lunar Trailing Orbit (LTO)an Earth orbit, at lunar distance. A later mission, using a Dragon and launched by a Falcon Heavy, performs a rendezvous with the ERV in the lunar trailing orbit, retrieves the sample container and breaks the chain of contact with Mars by transferring the sample into a sterile and secure container. With the sample contained, the retrieving spacecraft, makes a controlled Earth re-entry preventing any unintended release of pristine Martian materials into the Earths biosphere. Other capsule type vehicles and associated launchers may be applicable. An MSR launch in 2022 becomes the preferred option if the Mars 2020 rover is the previous sample caching vehicle. The analysis methods employed standard and specialized aerospace engineering tools. Mission system elements were analyzed with either direct techniques or by using parametric mass estimating relationships (MERs). The architecture was iterated until overall mission convergence was achieved on at least one path. Subsystems analyzed in this study include support structures, power system, nose fairing, thermal insulation, actuation devices, MA V exhaust venting, and GN&C. Best practice application of loads, mass growth contingencies, and resource margins were used. For Falcon Heavy capabilities and Dragon subsystems we utilized publically available data from SpaceX; published analyses from other sources; as well as our own engineering and aerodynamic estimates. Earth Launch mass is under 11 mt, which is within the estimated capability of a Falcon Heavy, with margin. Total entry masses between 7 and 10 mt were considered with closure occurring between 9 and 10 mt. Propellant mass fractions for each major phase of the EDL - Entry, Terminal Descent, and Hazard Avoidance were derived. An assessment of the entry condition effects on the thermal protection system (TPS), currently in use for Dragon missions, showed no significant stressors. A useful mass of 2.0 mt is provided and includes mass growth allowances for the MA V, the ERV, and mission unique equipment. We also report on alternate propellant options for the MA V and options for the ERV, including propulsion systems; crewed versus robotic retrieval mission; as well as direct Earth entry. International Planetary Protection (PP) policies as well as verifiable means of compliance with both forward and back contamination controls, will have a large impact on any MSR mission design. We identify areas within our architecture where such impacts occur. This work shows that emerging commercial capabilities can be effectively integrated into a mission to achieve an important planetary science objective.

Atmospheric entry studies for Uranus

The present paper describes parametric studies conducted to define the Uranus entry trade space. Two different arrival opportunities in 2029 and 2043, corresponding to launches in 2021 and 2034, respectively, are considered in the present study. These two launch windows factor in the 84-year orbital period, significant axial tilt, and the wide ring system of Uranus. As part of this study, an improved engineering model is developed for the Uranus atmosphere. This improved model is based on reconciliation of data available in the published literature and covers an altitude range of 0 km (1 bar pressure) to 5000 km. Two different entry scenarios are considered: 1) direct ballistic entry, and 2) aerocapture followed by entry from orbit. For ballistic entry a range of entry flight path angles are considered for probe entry masses ranging from 130 kg to 300 kg and diameters ranging from 0.8 m (Pioneer-Venus small probe scale) to 1.3 m (Galileo scale). The larger probes, which offer a larger packing volume, are considered in an attempt to accommodate more scientific instruments. For aerocapture a single case is studied to explore the feasibility and benefits of this option.

Conceptual stage separation from widebody subsonic carrier aircraft for space access

Stage separation is a critical technical issue for developing two-stage-to-orbit (TSTO) launch systems with widebody carrier aircraft that use air-breathing propulsion and launch vehicle stages that use rocket propulsion. During conceptual design phases, this issue can be addressed with a combination of engineering methods, computational fluid dynamics simulations, and trajectory analysis of the mated system and the launch vehicle after staging. The outcome of such analyses helps to establish the credibility of the proposed TSTO system and formulate a ground-based test programme for the preliminary design phase. This approach is demonstrated with an assessment of stage separation from the shuttle carrier aircraft. Flight conditions are determined for safe mated flight, safe stage separation, and for the launch vehicle as it commences ascending flight. Accurate assessment of aerodynamic forces and moments is critical during staging to account for interference effects from the proximities of the two large vehicles. Interference aerodynamics have a modest impact on the separation conditions and separated flight trajectories, but have a significant impact on the interaction forces.

Analysis of a hydrocarbon scramjet with augmented preburning

This paper presents the results of a feasibility study of a hydrocarbon scramjet design utilizing an augmented preburner upstream of the main fuel injector locations. The combustor design evaluated here is for a small hypersonic research vehicle. It consists of a preburner into which a small amount of fuel is burned with on-board liquid oxygen and injected into the main airflow, upstream of the main fuel injector locations, thus ensuring that combustion is present and uninterrupted. Two degrees of analysis are presented including a one-dimensional cycle analysis and a complete computational fluid dynamic analysis with finite-rate chemistry and a two-equation turbulence model. Comparison of these analyses show good agreement when the CFD-predicted fuel consumption schedule is used in the cycle analysis.

Water Injection Pre-Compressor Cooling Assist Space Access

Advances in space activity are linked to reductions in launch cost. Airbreathing propulsion assisted space access offers the potential for revolutionary change of the space operations paradigm. Horizontal launch of a space-access system provides mission flexibility, responsiveness, and affordability. One way to reduce launch cost is to increase the Mach number at which a launch vehicle is staged from a carrier aircraft. The water injection pre-compressor cooling (WIPCC) technology allows the operation of a turbine engine at higher than the design Mach number and altitude and provides enhanced thrust levels at elevated Mach numbers. The advantage of this technology is assessed with a modified QF-4C aircraft. Payloads are unachievable or marginal with an unmodified QF- 4C. However, payloads weighing around 150 pounds are plausible with this aircraft incorporating the WIPCC technology. This is an essential near-term technology for reducing launch cost to place small- and medium-weight payloads in low Earth orbit (LEO).

Analysis of a hypersonic waverider research vehicle with a hydrocarbon scramjet engine

The results of a feasibility study of a hypersonic waverider research vehicle with a hydrocarbon scramjet engine are presented. The integrated waverider/scramjet geometry is first optimized with a vehicle synthesis code to produce a maximum product of the lift-to-drag ratio and the cycle specific impulse, hence cruise range. Computational fluid dynamics (CFD) is then employed to provide a nose-to-tail analysis of the system at the on-design conditions. Some differences are noted between the results of the two analysis techniques. A comparison of experimental, engineering analysis and CFD results on a waverider forebody are also included for validation.