User:The coolest pair of space pants/sandbox

I am the coolest pair of space pants. I shall use my WikiEditing powers to write space-related articles.

Madness? This isn't madness.

THIS...

IS....

SPACE!

Also, here is the article I wish to elaborate upon:

Aeroshell

An aeroshell is a rigid heat-shielded shell that helps decelerate and protect a spacecraft from pressure, heat, and possible debris during hypersonic entry and descent into an atmosphere (see blunt body theory). Its main components consist of a heat shield (the forebody) and a back shell. The heat shield absorbs heat caused by drag during a spacecraft's atmospheric entry. The back shell carries the spacecraft's payload, along with other components such as a parachute, rocket engines, monitoring electronics and other devices.

It's purpose is used during the EDL process of a spacecraft's mission, or the Entry, Descent, and Landing process (source?). First, the aeroshell decelerates the spacecraft as it penetrates the planet’s atmosphere. The heat shield absorbs the resulting friction. During decent, the parachute is deployed and the heat shield is detached. Rockets located at the back shell are initiated to assist in the decrease of the spacecraft's descent. Airbags are also inflated to cushion the impact. The spacecraft bounces on the planet’s surface directly after the first impact The spacecraft's lander petals are deployed after the airbags are deflated and retracted. Communication throughout this entire process is relayed back and forth from mission control and the actual spacecraft through low-gain antennas that are attached to the back shell and on itself. Throughout the entry, descent, and landing stages, tones are sent back to earth in order to communicate the success of failure of each of these critical steps

=Components(NEW)= The heat shield of faces flow during a spacecraft's atmospheric penetration, allowing it to absorb the high aerodynamic heat caused from the entry. The backshell however acts as a finalizer for the encapsulation of the payload. The backshell contains the parachute, electronics and batteries that control pyrotechnic devices, a Litton LN-200 Inertial Measurement Unit, Rocket Assisted Descent rockets, and Transverse Impulse Rocket System.The parachute is located at the apex of the back shell and slows the spacecraft during entry, descent, and landing. The pyrotechnic control system releases devices such as nuts, rockets, and the parachute mortor. The Inertial Measurement Unit reports the orientation of the back shell while it is swaying underneath the parachute. Rocket Assisted Descent rockets provide approximately one ton of force within 2 seconds. Transverse Impulse Rocket System provide horizontal force to the back shell which helps orient the backshell to a more vertical position during the main Rocket Assisted Descent rocket burn (source?).

=Design Factors=

A spacecraft's mission objective determines what flight requirements are required to ensure mission success. These flight requirements are deceleration, heating, and impact/landing accuracy. A spacecraft must have maximum value of deceleration low enough to keep the weakest points of its vehicle in tact but high enough to penetrate the atmosphere without rebounding. Spacecraft structure and payload mass affect how much maximum deceleration it can stand. This force is represented by "g's", or Earth's gravitational acceleration. If its structure is well-designed and made from robust material (such as steel) enough, then it can withstand a higher amount of g's. However, payload needs to be considered. Just because the spacecraft's structure can withstand high g's does not mean it's payload can. For example, a payload of astronauts can only withstand 12 g's, or 12 times their weight. Values that are more than this baseline will cause death. It must also be able to withstand high temperature caused by the immense friction resulting from entering the atmosphere at hypersonic speed. Finally, it must be able to penetrate an atmosphere and land on a terrain accurately, without missing its target. A more constricted landing area calls for more strict accuracy. In such cases, a spacecraft will be more streamlined and possess a steeper re-entry trajectory angle. These factors combine to affect the re-entry corridor, the area in which a spacecraft must travel in order to avoid burning up or rebounding out of an atmosphere. All of these above requirements are met through the consideration, design, and adjustment of a spacecraft's structure and trajectory.

The overall dynamics of aeroshells are influenced by inertial and drag forces, as defined it this equation: ß=m/CdA where m is defined as the mass of the aeroshell and its respective loads and CdA is defined as the amount of drag force an aeroshell can generate during a freestream condition. Overall, β is defined as mass divided by drag force (mas per unit drag area). A higher mass per unit drag area causes aeroshell entry, descent, and landing to happen at low and dense points of the atmosphere while reduces the elevation capability and the timeline margin for landing. Factors that increase include heat load and rate, which causes the system to forcefully accommodate to the increase in thermal loads. This situation reduces the useful landed mass capability of entry, descent, and landing because an increase in thermal load leads to a heavier support structure and thermal protection system (TPS) of the aeroshell. Static stability also needs to be taken into consideration as it is necessary to maintain a high-drag altitude. This is why a sweeped aeroshell forebody as opposed to a blunt one is required; the previous shape ensures this factor’s existence but also reduces drag area. Thus, there is a resulting tradeoff between drag and stability that affects the design of an aeroshell’s shape. Lift-to-drag ratio is also another factor that needs to be considered. The ideal level for a lift-to-drag ration is at non-zero.

Trajectory
Trajectory can be changed by altering re-entry velocity and and re-entry flight-angle

Vehicle structure
=History= Four fundamental styles of aeroshells are the Viking-era 70 degree sphere-cone, the Mars Microprobe, the Aerosassist Flight Experiment (AFE), and swept bionic design (Theisinger, et al. 2009).

= References =

http://dx.doi.org/10.2514/1.43358 Button E.C., Lilley C.R., Mackenzie N.S., Sader J.E. Blunted-cone heat shields of atmospheric entry vehicles AIAA Journal, Volume 47, Issue 7, July 2009, Pages 1784-1787

Mars Exploration Rover Mission: The Mission. (n.d.). Retrieved March 18, 2015, from http://mars.nasa.gov/mer/mission/spacecraft_edl_aeroshell.html

http://arc.aiaa.org/doi/abs/10.2514/1.41136?journalCode=jsr John E. Theisinger and Robert D. Braun. "Multi-Objective Hypersonic Entry Aeroshell Shape Optimization", Journal of Spacecraft and Rockets, Vol. 46, No. 5 (2009), pp. 957-966. doi: 10.2514/1.41136

Mars Science Laboratory Aeroshell http://www.lockheedmartin.com/us/products/mars-science-laboratory-aeroshell.html

Flight Dynamics of an Aeroshell Using an Attached Inflatable Aerodynamic Decelerator http://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/20090020433.pdf

Three-Dimensional Aerodynamics Study for Mars Aeroshell in Nonequilibrium Flow http://enu.kz/repository/2010/AIAA-2010-4647.pdf

HIGH-TEMPERATURE STRUCTURES, ADHESIVES, AND ADVANCED THERMAL PROTECTION MATERIALS FOR NEXT-GENERATION AEROSHELL DESIGN http://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/20060002549.pdf

Returning from Space: Re-entry. (n.d.). Retrieved April 8, 2015, from https://www.faa.gov/other_visit/aviation_industry/designees_delegations/designee_types/ame/media/Section III.4.1.7 Returning from Space.pdf