Engineering topics

J Scoggins

Publications and source records attributed to J Scoggins.

3 records

NASA NTRSDate not supplied

Flagship-Class Uranus Orbiter and Probe Using Aerocapture

Exploration of the Ice Giants, especially Uranus, via orbiter and atmospheric probes, is required to answer pressing science questions that have been raised in the latest Decadal Survey. As the Ice Giants are the farthest planets from Earth, traditional fully-propulsive orbit insertion missions have transit times to the planetary bodies nearing 13-15 years and require a large amount of propellant (wet mass percentages of around 60-70%) for the orbit insertion maneuver, leaving less mass for the scientific payload and a planetary probe. Aerocapture uses aerodynamic forces generated by flight within a planetary atmosphere to decelerate and achieve orbit insertion. Aerocapture has been considered for several past missions but it has not been demonstrated. However, recent developments in thermal protection systems (TPS), guidance and control (G&C), and interplanetary navigation capabilities show the potential for using rigid, heritage entry vehicle configurations already flown at other planetary bodies for Ice Giants aerocapture. Aerocapture can robustly deliver spacecraft to Ice Giant orbits, while substantially increasing on-orbit payload mass (more than 40%) that can be used for a robust atmospheric entry probe. Additionally, the aerocapture maneuver would reduce the interplanetary transit time by 2-5 years (15-30%) relative to fully-propulsive orbit insertion. Recent work has shown that a flagship-class mission can be conducted in a shorter time than fully-propulsive missions if using aerocapture.

S Dutta↗

NASA NTRSDate not supplied

Aerosciences Implications for Uranus Aerocapture

Exploration of Uranus has been indicated as the highest priority new flagship planetary science missions for NASA in the 2022 Decadal Survey. Due to Uranus’ location as the second furthest planet from the Sun, interplanetary flight times of a traditional propulsive-capture orbiter can expect to take 13-15 years to reach Uranus while requiring up to two-thirds of the launch mass budget to be allocated to propellant alone. Aerocapture presents an alternative means to capture orbit around Uranus by using aerodynamic forces generated from flight through the planetary atmosphere to decelerate to orbital insertion while reducing time in interplanetary transit time and increasing on-orbit payload mass. To date, only one spacecraft (Voyager 2) has visited Uranus, and there have been no missions which have entered its atmosphere. While knowledge of planetary entry at rocky terrestrial planets with Air (N2/O2) and CO2 dominated atmospheres has greatly advanced over the past decades with a variety of missions to learn from, the H2/He composition and much larger atmosphere of ice giants such as Uranus poses new aerosciences implications which are not fully understood. These implications must be better understood not only for aerocapture, but for planetary entry at Uranus as a whole (such as a Uranus probe, as proposed by the 2022 Decadal Survey), as well as other ice giants like Neptune. To conduct a proper analysis of aerocapture methods, aerodynamic and aerothermal analysis of flight trajectories in Uranus atmosphere are required. Previous work has investigated aerocapture at Neptune (with similar atmosphere to Uranus) using a Mid-L/D configuration. Additional previous work considers the convective heating experienced in H2/He atmospheres. The current work looks to use heritage Low-L/D configurations, adding technical depth and maturation to analysis previously performed by Girija. Atmospheric flight at ice giants presents unique challenges, including but not limited to: fidelity of atmospheric models, large entry velocities due to location in the solar system, extended flight in rarefied flow conditions due to atmospheric scale, and unusual aerodynamic flow properties specific to Uranus and Ice Giant atmospheres.

Eli Shellabarger↗

NASA NTRSDate not supplied

Aerodynamics of a Uranus Aerocapture System Using a Mars-Heritage Entry Vehicle

Aerodynamic characteristics of an aerocapture system intended to deliver a flagship-class orbiter and probe planetary science mission to Uranus are presented. The aeroshell of the Mars Science Laboratory and Mars 2020 entry vehicles is proposed as a baseline for this system to reduce the amount of necessary technology development. Direct Simulation Monte Carlo and Navier-Stokes computational fluid dynamics solutions are used to characterize the aerodynamic performance of the Mars-heritage vehicle for aerocapture flight at Uranus. These results are incorporated into an aerodatabase for use in six degree-of-freedom trajectory studies and mission design. Updates are made to the Mars-heritage aerodynamic uncertainty model based on observations in the Uranus-specific computational data to ensure the model is conservatively bounding for the proposed flight space. Necessary modifications to the aeroshell for system packaging are found to have minimal effect on aerodynamic performance. The resulting aerodatabase and uncertainty model are used to show the existing Mars-heritage entry vehicles have sufficient aerodynamic performance to achieve required control margin for Uranus aerocapture.

Eli Shellabarger↗