Spelling suggestions: "subject:"aeroassisted maneuver"" "subject:"toassist maneuver""
1 |
Planetary Mission Design and Analysis Using Aeroassist ManeuversYe Lu (7116044) 14 August 2019 (has links)
<div>Mission designs have been focused on using proven orbital maneuvers (i.e., propulsive maneuvers and gravity-assist) to deliver spacecraft to planetary destinations. Aeroassist maneuvers, despite their potential benefits, have not been given serious considerations due to the perceived risk and complexity. As entry technologies mature, aeroassist maneuvers need to be considered more extensively. Currently, there is no tool available that can perform rapid preliminary mission designs using aeroassist maneuvers. In this dissertation, integrated design methodologies for aerocapture and aerogravity-assist are developed, which can be readily converted to design tools that enable rapid mission concept formulations. </div><div> </div><div>The aerocapture design methodology is used to develop extensive design rules and relations for aerocapture missions to Titan, Venus, and Uranus, considering a wide range of vehicle parameters and interplanetary trajectories. These design rules and relations are intended as a convenient resource for mission designers and system engineers to evaluate the feasibility of aerocapture (e.g., effects of V-infinity on aerocapture missions) and the relevant design requirements, such as choices for vehicle characteristics and TPS materials. In addition, potentials for inclination change for Titan aerocapture are also quantified, presenting additional benefits of using aerocapture. Given the unusual orientation of Uranus, the changes in inclination and shift of line of apsides are also quantified for Uranus aerocapture. </div><div> </div><div>A novel design methodology is developed for Saturn system missions using nontraditional aerogravity-assist maneuvers at Titan. Compared with the existing literature, the novel methodology explores a comprehensive design space by integrating design considerations for interplanetary trajectories, atmospheric trajectories, arrival geometries at Titan, and vehicle designs. The methodology enables preliminary design trades and allows the mission designer to assess the feasibility of Titan aerogravity-assist and quickly develop requirements for trajectory designs and vehicle designs. The methodology also identifies potential Saturn and Titan arrival conditions. Results for an example Enceladus mission and Saturn system mission are presented, showing that a Saturn arrival V-infinity of 7 km/s renders Titan aerogravity-assist feasible for an Enceladus mission, while using the current entry technology. </div><div> </div><div>Bank modulation and drag modulation have been considered separately for aeroassist vehicles in the literature. The investigation combines bank modulation and drag modulation to improve the control authorities for aeroassist vehicles and such improvements are quantified using numerical simulations for a wide range of vehicle design configurations. The results show the potential of using a low-L/D vehicle for aerocapture at Uranus using combined bank and drag modulation. </div><div><br></div>
|
2 |
System Analysis of a Numerical Predictor-Corrector Aerocapture Guidance ArchitectureRohan Gajanan Deshmukh (10587056) 07 May 2021 (has links)
<p>Aerocapture has been envisioned as a potential orbit
insertion technique for planetary destinations with an atmosphere. Despite not
being flight proven technique, many studies found in the literature and recent
mission proposals have employed aerocapture into their respective mission
designs. The potential varying levels of trajectory dispersions experienced during
atmospheric flight at each destination drives the need for robust and
fuel-efficient guidance and control solutions. Existing guidance algorithms
have relied on tracking precomputed reference trajectories, which are computed
using significant simplifications to the flight mechanics, are not generally
designed to be fuel-efficient, and require tedious performance gain tuning.
When simulated with higher levels of uncertainty, the existing algorithms have
been shown to produce large orbit insertion errors. Furthermore, existing
flight control methodologies have been limited in scope to bank angle
modulation. While some studies have introduced new methodologies, such as drag
modulation and direct force control, they haven’t been tested at the same level
of rigor as the existing methods. Advances in on-board computational power are
allowing for modern guidance and control solutions, in the form of numerical
predictor-corrector algorithms, to be realized. This dissertation presents an
aerocapture guidance architecture based on a numerical predictor-corrector
algorithm. Optimal control theory is utilized to formulate and numerically
obtain fuel-minimizing flight control laws for lifting and ballistic vehicles.
The unified control laws are integrated into a common guidance algorithm. The
architecture is utilized to conduct Monte Carlo simulation studies of
Discovery-class and SmallSat-class aerocapture missions at various planetary
destinations.</p>
|
3 |
A Systems Framework and Analysis Tool for Rapid Conceptual Design of Aerocapture MissionsAthul Pradeepkumar Girija (11068791) 22 July 2021 (has links)
Aerocapture offers a near propellantless and quick method of orbit
insertion at atmosphere bearing planetary destinations. Compared to
conventional propulsive insertion, the primary advantage of using
aerocapture is the savings in propellant mass which could be used to
accommodate more useful payload. To protect the spacecraft from the
aerodynamic heating during the maneuver, the spacecraft must be enclosed
in a protective aeroshell or deployable drag device which also provides
aerodynamic control authority to target the desired conditions at
atmospheric exit. For inner planets such as Mars and Venus, aerocapture
offers a very attractive option for inserting small satellites or
constellations into very low circular orbits such as those used for
imaging or radar observations. The large amount of propellant required
for orbit insertion at outer planets such as Uranus and Neptune severely
limits the useful payload mass that can delivered to orbit as well as
the achievable flight time. For outer planet missions, aerocapture opens
up an entirely new class of short time of flight trajectories which are
infeasible with propulsive insertion. A systems framework for rapid
conceptual design of aerocapture missions considering the
interdependencies between various elements such as interplanetary
trajectory and vehicle control performance for aerocapture is presented.
The framework provides a step-by-step procedure to formulate an
aerocapture mission starting from a set of mission objectives. At the
core of the framework is the ``aerocapture feasibility chart", a
graphical method to visualize the various constraints arising from
control authority requirement, peak deceleration, stagnation-point peak
heat rate, and total heat load as a function of vehicle aerodynamic
performance and interplanetary arrival conditions. Aerocapture
feasibility charts have been compiled for all atmosphere-bearing Solar
System destinations for both lift and drag modulation control
techniques. The framework is illustrated by its application to
conceptual design of a Venus small satellite mission and a
Flagship-class Neptune mission using heritage blunt-body aeroshells.
The framework is implemented in the Aerocapture Mission Analysis Tool
(AMAT), a free and open-source Python package, to enable scientists and
mission designers perform rapid conceptual design of aerocapture
missions. AMAT can also be used for rapid Entry, Descent, and Landing
(EDL) studies for atmospheric probes and landers at any
atmosphere-bearing destination.
|
Page generated in 0.0774 seconds