Earth aerobraking strategies for manned return from Mars

Abstract

Earth-return entry corridor analyses are performed to evaluate the atmospheric flight environment of manned return from Mars. Trajectory and performance differences between aerocapture and direct entry are assessed and quantified in terms of the required aerobrake lift-drag ratio (L/D), stagnation-point heating, and the significance of off-nominal atmospheric conditions. The Earth-return aerobraking scenarios compared are 1) aerocapture into a phasing orbit with a 24-h period, 2) aerocapture into a 500-km circular orbit, 3) and direct entry to splashdown. No significant differences between aerocapture to a 500-km circular orbit and direct entry were observed in terms of aerobrake L /D requirements, maximum deceleration, or peak stagnation-point heat rate. The importance of parking orbit selection is demonstrated for low entry velocity Earth-return missions from Mars and missions returning from the Moon. Additionally, a stagnation-point heating analysis revealed that in all cases the peak heat rate is large enough to require an ablative thermal protection system for manned return from Mars. However, for entry velocities of 12.5 km/s and less, the heating environment is of the same order of magnitude as that experienced during the Apollo program. To perform the entry analysis, two predictor-corrector guidance design strategies were developed. Use of a predictor-corrector technique was shown to provide adequate flight margin for managing off-nominal atmospheric conditions.Nomenclature reference surface area, m 2 drag coefficient gravitational constant, 9.806 m/s 2 lift-to-drag ratio vehicle mass, kg ballistic coefficient, kg/m 2 convective stagnation-point heat rate, W/cm 2 radiative stagnation-point heat rate, W/cm 2 total stagnation-point heat load, J/cm 2 total stagnation-point heat rate, W/cm 2 inertial velocity at the atmospheric interface, km/s angle of attack propulsive velocity change, m/s fly able corridor width, deg inertial flight-path angle at the atmospheric interface, deg atmospheric density, kg/m 3 1976 standard atmospheric density, kg/m 3

Flexible piloted Mars missions using the TIHTUS engine

“…For the aeromaneuvers at Mars or at Earth an assessment of the heliocentric transit and the atmospheric phase yields that the maximum relative velocity should be v ∞,max = 6 km/s at Mars and v ∞,max = 9.5 km/s at Earth (see also Refs. [7,8,33]). For safety reasons the POV first performs an aerocapture into the ERV's parking orbit before landing on the surface.…”

Capture of small near-Earth asteroids to Earth orbit using aerobraking

“…The same list of asteroids in Table 1 and Table 2 is investigated and the optimal transfers for capturing those asteroids around the Earth using aerobraking can again be obtained with NSGA-II using Eq. (28) or Eq. (29) as the objective function.…”

“…Recently, technologies for such aerobraking manoeuvres have been studied extensively [22][23][24][25], with the Magellan [26] and MGS [27] spacecraft demonstrating the feasibility of multi-pass aerobraking for robotic missions. Moreover, Earth aerobraking has been also been proposed to design Earth-return trajectories from Mars [28] or to transfer to a low Earth orbit from a generic hyperbolic trajectory [29]. Moreover, Sonter [5] proposed the use of an "Earth-fabricated, LEO-fabricated, or asteroid-fabricated aerobrake" to return captured asteroid material to low Earth orbit.…”

Unsteady pulsating flowfield over spiked axisymmetric forebody at hypersonic flows

“…30,31 Such blunt forebody shapes are only preferred for atmospheric re-entry vehicles where minimizing aerodynamic heating is a priority. 32 However, in the case of vehicles traveling at high speeds within the atmosphere, reducing aerodynamic drag is of utmost importance to enhance its range and efficiency. The spiked forebody in any form, either in missiles 33,34 or engine intakes, 35,36 reduces the overall drag as the spike creates a low pressure, recirculating, dead air region in front of the forebody.…”