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At least 73 records · Page 4
All sourcesNASA NTRSDOE OSTI
NASA NTRS2002

Application of Accelerometer Data to Mars Odyssey Aerobraking and Atmospheric Modeling

Aerobraking was an enabling technology for the Mars Odyssey mission even though it involved risk due primarily to the variability of the Mars upper atmosphere. Consequently, numerous analyses based on various data types were performed during operations to reduce these risk and among these data were measurements from spacecraft accelerometers. This paper reports on the use of accelerometer data for determining atmospheric density during Odyssey aerobraking operations. Acceleration was measured along three orthogonal axes, although only data from the component along the axis nominally into the flow was used during operations. For a one second count time, the RMS noise level varied from 0.07 to 0.5 mm/s2 permitting density recovery to between 0.15 and 1.1 kg per cu km or about 2% of the mean density at periapsis during aerobraking. Accelerometer data were analyzed in near real time to provide estimates of density at periapsis, maximum density, density scale height, latitudinal gradient, longitudinal wave variations and location of the polar vortex. Summaries are given of the aerobraking phase of the mission, the accelerometer data analysis methods and operational procedures, some applications to determining thermospheric properties, and some remaining issues on interpretation of the data. Pre-flight estimates of natural variability based on Mars Global Surveyor accelerometer measurements proved reliable in the mid-latitudes, but overestimated the variability inside the polar vortex.

Tolson, R. H.↗
NASA NTRS2002

The Development and Evaluation of an Operational Aerobraking Strategy for the Mars 2001 Odyssey Orbiter

The Mars 2001 Odyssey Orbiter successfully completed the aerobraking phase of its mission on January 11, 2002. This paper discusses the support provided by NASA's Langley Research Center to the navigation team at the Jet Propulsion Laboratory in the planning and operational support of Mars Odyssey Aerobraking. Specifically, the development of a three-degree-of-freedom aerobraking trajectory simulation and its application to pre-flight planning activities as well as operations is described. The importance of running the simulation in a Monte Carlo fashion to capture the effects of mission and atmospheric uncertainties is demonstrated, and the utility of including predictive logic within the simulation that could mimic operational maneuver decision-making is shown. A description is also provided of how the simulation was adapted to support flight operations as both a validation and risk reduction tool and as a means of obtaining a statistical basis for maneuver strategy decisions. This latter application was the first use of Monte Carlo trajectory analysis in an aerobraking mission.

Tartabini, Paul V.↗
NASA NTRS2007

Mars Reconnaissance Orbiter Operational Aerobraking Phase Assessment

The Mars Reconnaissance Orbiter (MRO) was inserted into orbit around Mars on March 10, 2005. After a brief delay, it began the process of aerobraking - using the atmospheric drag on the vehicle to reduce orbital period. The aerobraking phase lasted approximately 5 months (April 4 to August 30, 2006), during which teams from the Jet Propulsion Laboratory, Lockheed Martin Space Systems Corporation, and NASA Langley Research Center worked together to monitor and maneuver the spacecraft such that thermal margin on the solar arrays was maintained while schedule margin was upheld to provide a final local mean solar time (LMST) at ascending node of 3:00pm on the final aerobraking orbit. This paper will focus on the contribution of the flight mechanics team at NASA Langley Research Center (LaRC) during the aerobraking phase of the MRO mission.

Prince, Jill L.↗
NASA NTRS2011

Implementation and Simulation Results using Autonomous Aerobraking Development Software

An Autonomous Aerobraking software system is currently under development with support from the NASA Engineering and Safety Center (NESC) that would move typically ground-based operations functions to onboard an aerobraking spacecraft, reducing mission risk and mission cost. The suite of software that will enable autonomous aerobraking is the Autonomous Aerobraking Development Software (AADS) and consists of an ephemeris model, onboard atmosphere estimator, temperature and loads prediction, and a maneuver calculation. The software calculates the maneuver time, magnitude and direction commands to maintain the spacecraft periapsis parameters within design structural load and/or thermal constraints. The AADS is currently tested in simulations at Mars, with plans to also evaluate feasibility and performance at Venus and Titan.

Maddock, Robert W.↗
NASA NTRS1993

The Magellan Venus Mapping Mission: Aerobraking Operations

The orbit of the Magellan spacecraft was circularized during a 70 day aerobraking phase, which ended on August 3, 1993. Shrinking the orbit apoapsis from 8467 km down to 541 km was required to obtain meaningful gravity science data at high and moderate latitudes. Aerobraking was the only way to reach this nearly-circular orbit, since the amount of propellant on board Magellan was at least an order of magnitude too small to circularize propulsively. This paper will describe the steps taken by the Magellan Flight Team to successfully aerobrake the Magellan spacecraft into the nearly-circular orbit. Magellan is currently in a 541 by 197 km altitude orbit around the planet Venus. This paper will briefly describe the Magellan mission history and hardware, the goals of the continuing Magellan mission, the exciting aerobraking phase, and other science objectives beyond the primary goal of producing a high-resolution global-gravity map of Venus.

Griffith, Douglas G.↗
NASA NTRS2019

Leveraging Mars aerobraking experience for the Venus environment

Aerobraking was first demonstrated at Venus during the Magellan extended mission in 1993 and on every Mars orbiter since, from the Mars Global Surveyor (MGS) in 1997 to ESA’s Trace Gas Orbiter (TGO) in 2017. This paper illustrates the differences between aerobraking at Venus and at Mars from both the astrodynamics and thermal perspectives. It shows how the periapsis velocity hammers the drag versus aerothermal heating relationship with comparable aerothermal heating limits and initial conditions at Mars and at Venus. Even though there are noticeable differences in the aerobraking environment between these two planets, the Mars heritage operations, processes, tactics, and strategy remain the same while addressing these differences in mission design and environment. Additionally, the spacecraft design requirements, capabilities, and thermal guards are retained across projects and planets. The operations processes and procedures developed over the 20 years of Mars experience can be equally applied back to the birthplace of aerobraking: Venus.

Wallace, Mark S.↗
NASA NTRS1994

Aerobraking the Magellan Spacecraft in Venus Orbit

A spacecraft which was not designed for atmospheric entry was successfully flown in the sensible atmosphere of Venus during the periapsis passes of more than 700 orbits, thus becoming the first spacecraft to demonstrate the use of aerobraking to significantly alter the shape of its orbit at another planet. This experimental operation utilized the force imparted by atmospheric drag near periapsis to reduce the altitude of apoapsis by nearly 8000 km using little propellant. A description of the Magellan spacecraft is briefly reviewed; its configuration and operation during aerobraking is discussed, as are its behavior in the atmosphere, concerns for possible damage, the resulting orbit, and the unique demands placed on the spacecraft controllers and JPL's Deep Space Network tracking facility (DSN), during the aerobraking operation.

Magellan Venus aerobraking↗
NASA NTRS1972

Space tug aerobraking study. Volume 1: Executive summary

The feasibility and practicality of employing an aerobraking trajectory for return of the reusable space tug from geosynchronous orbit was investigated. The aerobraking return trajectory modes employ transfer ellipses from high orbits which have low perigee altitudes wherein the earth's sensible atmosphere provides drag to reduce the tug return delta velocity requirements and thus decrease the required return trip propulsive energy. Aerodynamics, aerothermodynamics, trajectories, guidance and control, configuration concepts, materials, weights and performance were considered. Sensitivities to trajectory uncertainties, atmospheric anomalies and reentry environments were determined. New technology requirements and future studies required to further enhance the aerobraking potential were identified.

Corso, C. J.↗
NASA NTRS1981

Optimization of aerobraked orbital transfer vehicles

A new method for utilizing the upper atmosphere to modify earth orbital trajectories through use of a pressure supported drag brake has been previously proposed. Analytical results and initial wind tunnel test data indicate that there is considerable improvement available to the original aerobraking concept. Optimization of the drag brake with respect to size versus structural heating, and the application of more advanced cooling techniques, indicates that reductions in weight and volume of the aerobraking system by 50 percent should be possible. Additional analysis indicates that further improvements might be available through use of a alternate drag control mode which eliminates the need to throttle the vehicle main engine during the aerobraking maneuver.

Andrews, D. G.↗
NASA NTRS1981

Aerobraking techniques for planetary missions

Aerobraking techniques are applied to trajectory design for the VOIR (Venus Orbiting Imaging Radar) mission to enhance overall mission performance. The approach can be used for other planetary missions such as a Titan orbiter or a Mars sample return to earth. The orientation of the elliptical insertion orbit must be chosen in such a way that the combined effects of solar gravity, central-body harmonics, and drag on periapsis altitude are minimized to avoid frequent maneuvers. The selection of the base and width of a corridor for periapsis altitude depends upon the temperature and integrated heat of the aerobrake shield, the atmospheric density profile, the duration of aerobraking, the number of maneuvers, the time available between maneuvers, and uncertainties in the central-body gravity field and atmospheric density. Flight path profiles for an aerodynamically stable spacecraft and an inertially fixed spacecraft passing through the free molecular flow regime, as well as the transitional flow regime, are illustrated

Tang, C. C. H.↗
NASA NTRS1981

Aerobraking mission design - Mission domain and mass performance

The work reported comprises part of an Aerobraking Study that sought to establish a 'feasible mission design, navigation design, and MOS design and to show the desirability of aerobraking for the Venus Orbiting Imaging Radar (VOIR) mission by assessing mission performance, cost, and risk'. The developed software assesses accurately the mass performance of aerobraking and chemical missions that place a spacecraft in orbit about another planet. All injection date/arrival data combinations that provide a trajectory with adequate mass performance are available for further study. The considered analysis has been applied to the Type I trajectories from earth to Venus in 1988. The analysis can easily be applied to missions to Mars and to Titan. The intersection of the determined mass performance domain with the stable orbit domain provides an adequate mission domain for VOIR 1988.

Kerridge, S. J.↗
NASA NTRS1987

Heat Shields for Aerobrakes

Performances of three types of heat protectors predicted. Estimates of expected performances of heat shields for conical drag brake presented in paper. Drag brakes, or aerobrakes, being considered as devices for slowing space vehicles when they return to Space Shuttle altitudes from higher satellite altitudes after supply missions. Aerobrakes add less weight than do retro-rockets for same purpose and consume no fuel. Paper provides general information on sensitivity of performance to thermal and physical properties of materials used in aerobrakes. Information useful to both designers of brakes and developers of materials for brake fabrication on aerospace structures.

Pitts, W. C.↗
NASA NTRS1987

The challenge of aerobraking

The system efficiencies obtainable through the synergistic interaction of a LEO spaceport, earth-to-spaceport transportation, and a space-based, reusable aerobraking orbit transfer vehicle, are discussed with a view to NASA's next-century requirements. Attention is given to low Reynolds number hypersonic aerothermodynamic phenomena that will be encountered in aerobraking maneuvers, together with tasks of characterizing nonequilibrium chemistry and thermodynamics through ground experiments, computational chemistry, and CFD. Also noted are the requirements of an aeroassist flight experiment furnishing verification of current understanding of aerobraking vehicle design criteria.

Ried, Robert C.↗
NASA NTRS1988

A review of aerobraking for Mars missions

This paper describes prior and current studies of Mars aerobraking, which is a key element in robotic and manned missions to Mars and in the earth-return missions. It is pointed out that, while the studies of the 1960's assumed launch from and return to the earth's surface, current mission scenarios assume departure from and return to an earth orbiting space station, making it necessary to reassess aerobraking for Mars missions. Current studies propose a blunt low-L/D vehicle for both Mars and earth aerobraking. The vehicle's salient design issues such as the lift-to-drag ratio, the ballistic coefficient, and the aerodynamic heating and convective heating considerations are discussed.

Walberg, Gerald D.↗
NASA NTRS1990

Aerobrakes For A Manned Mars Mission

Paper presents results of study of aerobraking in manned mission to Mars. Describes geometry and aerodynamic characteristics of aerobraked vehicle. Discusses computer program, WTRAJ, used to simulate trajectories near planets. Analyzes aerocapture processes for both Mars and Earth. Examines mass efficiency, or saving in propellant mass, afforded by aerobraking.

Menees, G. P.↗
NASA NTRS1990

The aerobraking space transfer vehicle

With the advent of the Space Station and the proposed Geosynchronous Operation Support Center (GeoShack) in the early 21st century, the need for a cost effective, reusable orbital transport vehicle has arisen. This transport vehicle will be used in conjunction with the Space Shuttle, the Space Station, and GeoShack. The vehicle will transfer mission crew and payloads between low earth and geosynchronous orbits with minimal cost. Recent technological advances in thermal protection systems such as those employed in the Space Shuttle have made it possible to incorporate and aerobrake on the transfer vehicle to further reduce transport costs. The research and final design configuration of the aerospace senior design team from VPISU, working in conjunction with NASA, are presented. The topic of aerobraking and focuses on the evolution of an Aerobraking Space Transfer Vehicle (ASTV), is addressed.

Andrews, Glen↗
NASA NTRS1991

Aerobrake assembly with minimum Space Station accommodation

The minimum Space Station Freedom accommodations required for initial assembly, repair, and refurbishment of the Lunar aerobrake were investigated. Baseline Space Station Freedom support services were assumed, as well as reasonable earth-to-orbit possibilities. A set of three aerobrake configurations representative of the major themes in aerobraking were developed. Structural assembly concepts, along with on-orbit assembly and refurbishment scenarios were created. The scenarios were exercised to identify required Space Station Freedom accommodations. Finally, important areas for follow-on study were also identified.

Katzberg, Steven J.↗
NASA NTRS1991

Technologies for aerobraking

Aerobraking is one of the largest contributors to making both lunar and Mars missions affordable. The use of aerobraking/aeroassist over all propulsive approaches saves as much as 60 percent of the initial mass required in low earth orbit (LEO); thus, the number and size of earth to orbit launch vehicles is reduced. Lunar transfer vehicles (LTV), which will be used to transport personnel and materials from LEO to lunar outpost, will aerobrake into earth's atmosphere at approximately 11 km/sec on return from the lunar surface. Current plans for both manned and robotic missions to Mars use aerocapture during arrival at Mars and at return to Earth. At Mars, the entry velocities will range from about 6 to 9.5 km/sec, and at Earth the return velocity will be about 12.5 to 14 km/sec. These entry velocities depend on trajectories, flight dates, and mission scenarios and bound the range of velocities required for the current studies. In order to successfully design aerobrakes to withstand the aerodynamic forces and heating associated with these entry velocities, as well as to make them efficient, several critical technologies must be developed. These are vehicle concepts and configurations, aerothermodynamics, thermal protection system materials, and guidance, navigation, and control systems. The status of each of these technologies are described, and what must be accomplished in each area to meet the requirements of the Space Exploration Initiative is outlined.

Cooper, David M.↗