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NASA NTRS2012

Development of Autonomous Aerobraking (Phase 1)

The NASA Engineering and Safety Center received a request from Mr. Daniel Murri (NASA Technical Fellow for Flight Mechanics) to develop an autonomous aerobraking capability. An initial evaluation for all phases of this assessment was approved to proceed at the NESC Review Board meeting. The purpose of phase 1 of this study was to provide an assessment of the feasibility of autonomous aerobraking. During this phase, atmospheric, aerodynamic, and thermal models for a representative spacecraft were developed for both the onboard algorithm known as Autonomous Aerobraking Development Software, and a ground-based "truth" simulation developed for testing purposes. The results of the phase 1 assessment are included in this report.

Murri, Daniel G.↗

NASA NTRS2008

Mars Reconnaissance Orbiter Aerobraking Navigation Operation

After a seven-month interplanetary cruise, the Mars Reconnaissance Orbiter arrived at Mars and executed a 1.0 km/s Mars Orbit Insertion (MOI) maneuver. The post-MOI orbit was highly elliptical with a 35 hour, 428 km x 45000 km altitude orbit. To establish a useful science orbit, the navigation team used an aerobraking technique to guide the spacecraft into a 2-hour, 255 km x 320 km altitude orbit. This paper details the aerobraking navigation operation strategy and flight results. It also describes the aerobraking key requirements and navigation challenges.

Long, Stacia M.↗

NASA NTRS2018

Mars Optimal Aerobrake Maneuver Estimation

Mars science satellites often perform orbit changes to obtain different measurements, ground tracks or relay operations. Large reductions in semi-major axis and eccentricity can be done efficiently using the atmospheric drag, a.k.a aerobrake. Aerobraking is one of the most challenging planetary orbit maneuvers in terms of planning and operations. The most important consideration for aerobraking is maintaining the spacecraft's periapsis within an allocated atmospheric density corridor, which is accomplished by raising or lowering periapsis through one or a series of very small and short maneuvers. These maneuvers must be performed as efficiently as possible due to propellant constraints. Work herein details a fast and accurate method to calculate the required impulsive velocity changes in the orbit to guarantee that the spacecraft remains in a prescribed density corridor. The method makes use of the orbit's state transition matrix to map the solution space around the reference orbit. It evaluates the most efficient maneuver epochs to target a given periapsis change with a linear optimal control for single or multiple maneuvers. A fast calculation of the maneuver allows for a more comprehensive evaluation of the trade space, and the selected maneuver may be re-targeted later with a higher- fidelity model. Comparisons against fully propagated models and direct method optimizations demonstrate the new method's performance.

Sarli, Bruno V.↗

NASA NTRS1993

Navigating the Magellan Aerobrake

The Magellan spacecraft has been aerobraked into a 197 x 541 km near-circular orbit around Venus from which it is conducting a high-resolution gravity mapping mission. This was the first interplanetary aerobrake maneuver and involved flying the spacecraft through the upper reaches of the Venusian atmosphere 730 times over a 70 day period.

Magellan aerobrake Venusian↗

NASA NTRS1999

The Strategy for the Second Phase of Aerobraking Mars Global Surveyor

This paper focuses on and describes the strategy developed for the second phase of aerobraking MGS. This description includes the baseline aerobraking flight profile and the key trajectory metrics that were monitored in order to successfully guide the spacecraft to its desired mapping orbit.

aerobraking↗

NASA NTRS1996

Aerobraking at Mars: The MGS Mission

The Mars Global Surveyor (MGS) mission, scheduled for launch in November 1996, will employ aerobraking as a means of reaching a low altitude, sun-synchronous mapping orbit. This technique is necessary to minimize the cost of the mission. The dry mass of the spacecraft and the launch vehicle capability do not permit an all-propulsive transfer to the desired orbit. Aerobraking concepts are discussed.

Mars↗

NASA NTRS1998

Mars Global Surveyor Aerobraking at Mars

This paper describes the areobraking strategy developed for the MGS mission. In addition, this paper describes the aerobraking progress of the MGS spacecraft made following a three week aerobraking hiatus that occurred in October 1997.

Mars↗

NASA NTRS1983

Low L/D aerobrake test at Mach 10

An aerobraking Orbital transfer vehicle may be used to increase the Space Shuttle mission capability to and from high orbits. A Mach 10 wind-tunnel test was performed for a low lift-drag aerobrake, to define a preliminary aerothermal environment for this candidate concept. Test hardware simulated the ribs and stretched fabric of conceptual flight hardware. Pressures, paint-melting histories, and oilflow data were measured on the brake. Pressure and thermocouple heating rate data were measured on the payload. Brake peak heating is at the edge at all angles of attack, although the stagnation point is not outboard of 75 percent radius even at 20 degrees angle of attack. Brake ribs show slightly higher heating than flats, although pressures are essentially constant. Payload peak heating occurs near 12 degrees angle of attack, and is 30 percent of the sphere stagnation point heating (for a sphere of brake diameter). Payload pressure distributions follow the heating pattern. Reynolds number effects are small on the brake and large on the payload, for the range of test conditions: 0.4-1.0 million/foot.

Hair, L. M.↗

NASA NTRS1984

Aerothermodynamic heating analysis of aerobraking and aeromaneuvering orbital-transfer vehicles

The thermal-protection requirements of two aeroassisted orbital-transfer vehicles (AOTVs) are analyzed for return missions between the geosynchronous and Shuttle orbits. One of the designs is a specialized version of a previously proposed generic aerobraking vehicle that is capable of only delivery-type operations. The other is a high-lift aeromaneuvering vehicle that is optimized for low-earth orbit sortie missions involving large, multiple plane-inclination changes. The aerothermal environment of the aerobraking vehicle is analyzed using state-of-the-art methods for nonequilibrium-radiative and convective heating that incorporate refinements unique to the configuration. The heating analysis of the aeromaneuvering vehicle required the development of a flow-field model for rarefied-hypersonic flow over a lifting surface at incidence. The predicted aerothermodynamic heating characteristics for both vehicles are correlated with thermal-control requirements and flight performance capabilities for the specified mission guidelines. The results help identify technical issues related to the development of future operational systems.

Davies, C. B.↗

NASA NTRS1984

A comparison of aerobraking and aerocapture vehicles for interplanetary missions

Several design features for employing aerobraking and aerocapture techniques on interplanetary spacecraft are described. Recent studies have identified silica fabrics mounted on carbon composite ribs as suitable aerobraking spacecraft shield materials. Aerocapture is best achieved with a biconic aeroshell design, with the aeroshell supported by Al honeycomb panels and allowing primitive aerodynamic maneuverability. The aeroshell would be covered with thermal protection materials capable of elevated temperatures of magnitudes that are a function of the expected atmospheric density, the surface area, the entry speed, spacecraft mass and maneuverability. Both technologies are concluded ready for implementation and development costs are estimated for various missions, showing that aerocapture will provide for greater payload masses, except for a Jupiter mission.

Hoffman, S.↗

NASA NTRS1986

Aerobraking

This paper presents a discussion of the basic principles of aerobraking. Typical results are given for the application of aerobraking to orbital capture at Mars, descent to the Mars surface and orbital capture on return to Earth.

V A Dauro↗

NASA NTRS1987

A comparison of two conformal mapping techniques applied to an aerobrake body

Conformal mapping is a classical technique which has been utilized for solving problems in aerodynamics and hydrodynamics. Conformal mapping has been successfully applied in the construction of grids around airfoils, engine inlets and other aircraft configurations. Conformal mapping techniques were applied to an aerobrake body having an axis of symmetry. Two different approaches were utilized: (1) Karman-Trefftz transformation; and (2) Point Wise Schwarz Christoffel transformation. In both cases, the aerobrake body was mapped onto a near circle, and a grid was generated in the mapped plane. The mapped body and grid were then mapped back into physical space and the properties of the associated grids were examined. Advantages and disadvantages of both approaches are discussed.

Hommel, Mark J.↗

NASA NTRS1989

Aerobrake heating rate sensitivity study for the Aeroassist Flight Experiment (AFE)

The sensitivities associated with the prediction of the Aeroassist Flight Experiment (AFE) vehicle's aerothermodynamic environment are presently evaluated in order to assess the heating-rate uncertainties of the AFE's aerobrake component, as a function of time in various trajectories, and as a function of distance around the aerobrake. Relative importance is evaluated by means of the Boundary Layer Integral Matrix Procedure for such areas of uncertainty as the trajectory parameters, the catalycity of the thermal-protection tiles, the nose radius variation/surface pressure distribution, and viscous interaction effects.

Rochelle, W. C.↗

NASA NTRS1991

A predictor-corrector guidance algorithm for use in high-energy aerobraking system studies

A three-degree-of-freedom predictor-corrector guidance algorithm has been developed specifically for use in high-energy aerobraking performance evaluations. The present study reports on both the development and capabilities of this guidance algorithm to the design of manned Mars aero-braking vehicles. Atmospheric simulations are performed to demonstrate the applicability of this algorithm and to evaluate the effect of atmospheric uncertainties upon the mission requirements. The off-nominal conditions simulated result from atmospheric density and aerodynamic characteristic mispredictions. The guidance algorithm is also used to provide relief from the high deceleration levels typically encountered in a high-energy aerobraking mission profile. Through this analysis, bank-angle modulation is shown to be an effective means of providing deceleration relief. Furthermore, the capability of the guidance algorithm to manage off-nominal vehicle aerodynamic and atmospheric density variations is demonstrated.

Braun, Robert D.↗

NASA NTRS1991

Design and fabrication of an aerobrake mock-up

The paper reports on the design and fabrication of a Mars aerobrake mockup that has been used in a series of underwater neutral buoyancy tests designed to address this on-orbit assembly issue. Particular attention is given to the aerobrake shell, truss components, and fastener issues. It is noted that soft docking alignment fasteners, fasteners between petals, and fasteners to connect the petal-to-petal truss members are all needed for this mockup.

Lee, Gordon K. F.↗

NASA NTRS1991

On the computation of near wake, aerobrake flowfields

Simulations of the near wake flowfield behind three aerobrakes have been implemented with Program LAURA, an algorithm for obtaining the numerical solution to the governing equations for three-dimensional, viscous, hypersonic flows in chemical and thermal nonequilibrium. Emphasis is placed on understanding the conditons which are likely to cause the shear layer to impinge on a payload positioned behind the aerobrake. A linear relationship between shear layer deflection angle and angle of attack (or lift-to-drag ratio) has been identified in several ground based tests. A similar relation appears in the numerical simulations, though there is some evidence that deflection angels may increase somewhat due to the effects of gas chemistry. Shear layer impingement can raise local heating levels a factor of 10 higher than levels present without impingement. Payload heating levels near impingement points are a larger percentage of stagnation point heating levels at higher altitudes and peak payload heating levels are likely to occur earlier in the trajectory than peak heating on the forebody stagnation point.

Gnoffo, Peter A.↗

NASA NTRS1992

Structural performance of two aerobrake hexagonal heat shield panel concepts

Structural sizing and performance are presented for two structural concepts for an aerobrake hexagonal heat shield panel. One concept features a sandwich construction with an aluminum honeycomb core and thin quasi-isotropic graphite-epoxy face sheets. The other concept features a skin-rib isogrid construction with thin quasi-isotropic graphite-epoxy skins and graphite-epoxy ribs oriented at 0, +60, and -60 degs along the panel. Linear static, linear bifurcation buckling, and nonlinear static analyses were performed to compare the structural performance of the two panel concepts and assess their feasibility for a lunar transfer vehicle aerobrake application.

Dorsey, John T.↗

NASA NTRS1991

Methodology and critical performance characteristics of aerobrake maneuvers for earth return

An effective general methodology for aerobraking in medium and high energy earth returns either with transfer to LEO or return to the surface is presented. Equations are derived or reformulated to indicate performance bounds for a generic aerobrake maneuver whose primary goal is the safe capture of a returning spacecraft. A secondary goal of this maneuver is the ability to maximize the range of entry conditions while minimizing both the strain of thermal and structural loads and the propulsive effort required to achieve a particular destination orbit.

Goodrick, Thomas F.↗