What is atmospheric entry?

Atmospheric entry is the process by which an object moves from outer space into and through the gaseous envelope surrounding a planet, dwarf planet, or natural satellite. This passage through the atmosphere is often referred to by the entry velocity or V_entry.

What are the two primary types of atmospheric entry?

Atmospheric entry can be either uncontrolled, as seen with astronomical objects or space debris, or controlled, which involves the navigation or predetermined course of a spacecraft. Controlled atmospheric entry, descent, and landing are collectively known as EDL.

What physical forces does an object experience during atmospheric entry?

Objects entering an atmosphere encounter atmospheric drag, which exerts mechanical stress, and aerodynamic heating. Aerodynamic heating is primarily caused by the compression of air in front of the object, but drag also contributes.

What are the potential consequences of atmospheric entry forces on an object?

The forces experienced during atmospheric entry can lead to mass loss through ablation, complete disintegration of smaller objects, or even explosion if the object has low compressive strength.

What are the typical speeds observed during atmospheric entry?

Entry speeds can range significantly, from approximately 7.8 km/s for objects entering from low Earth orbit to around 12.5 km/s for probes like the Stardust spacecraft.

Why are retrorockets generally impractical for slowing down an entire spacecraft during atmospheric entry?

Retrorockets are generally impractical for the entire reentry procedure because spacecraft possess very high kinetic energies that need to be dissipated. While they can be used for final deceleration, relying on them solely for the entire process is highly inefficient and impractical.

What is required for crewed spacecraft before deploying parachutes during reentry?

For crewed space vehicles, it is essential to slow down to subsonic speeds before parachutes or air brakes can be safely deployed.

How do ballistic warheads and expendable vehicles differ in their approach to atmospheric entry compared to crewed spacecraft?

Ballistic warheads and expendable vehicles do not need to slow down significantly during reentry; in fact, they are designed to be streamlined to maintain their speed. They are not designed for crew survival or gentle deceleration.

Why do high-altitude parachute jumps from near-space not require heat shielding?

High-altitude parachute jumps, starting from relative rest within or near the atmosphere, do not achieve velocities high enough to generate significant atmospheric heating, thus negating the need for heat shielding.

What are the conventional altitudes for atmospheric entry on different celestial bodies?

For Earth, atmospheric entry is conventionally considered to begin at the Kármán line (100 km). On Venus, entry occurs at a higher altitude of approximately 250 km, while on Mars, it begins around 80 km.

What types of trajectories typically result in hypersonic entry speeds?

Objects typically enter atmospheres at hypersonic speeds due to their sub-orbital (like ICBMs), orbital (like Soyuz), or unbounded (like meteors) trajectories.

What alternative method can be used for controlled atmospheric entry in planets with thick atmospheres or strong gravity?

Buoyancy can serve as an alternative method for controlled atmospheric entry, particularly useful for planets like Venus, Titan, or the giant planets where high-velocity hyperbolic entry is complicated by atmospheric density or gravitational forces.

Who first described the concept of an ablative heat shield, and what was their reasoning?

Robert Goddard described the concept of an ablative heat shield as early as 1920. He reasoned that by using layers of infusible material with poor heat conductors, the surface erosion experienced by meteors traveling at high speeds could be minimized.

How did the development of reentry vehicles progress with the increasing range of ballistic missiles?

Early short-range missiles like the V-2 faced stabilization and aerodynamic stress issues but not significant heating. Medium-range missiles required ceramic composite heat shielding, while the first ICBMs, with much longer ranges, necessitated modern ablative heat shields and blunt-shaped vehicles.

What counterintuitive discovery did H. Julian Allen and A. J. Eggers Jr. make regarding reentry vehicle shapes?

In 1951, H. Julian Allen and A. J. Eggers Jr. discovered that a blunt shape, which creates high drag, actually makes for the most effective heat shield. This is because the bluntness pushes the shock wave and heated air layer away from the vehicle.

What is the relationship between an entry vehicle's drag coefficient and its heat load?

The heat load experienced by an entry vehicle is inversely proportional to its drag coefficient. This means that a higher drag coefficient, achieved with a blunter shape, results in a lower heat load on the vehicle.

What is Entry, Descent, and Landing (EDL)?

EDL, or Entry, Descent, and Landing, refers to the phase of a spacecraft's journey that includes its passage through an atmosphere, its deceleration, and its final touchdown or splashdown on a planetary body.

What is the primary objective when designing a spacecraft for atmospheric entry?

The fundamental goal is to dissipate the immense kinetic energy of a hypersonic spacecraft as it enters an atmosphere, slowing it down to zero velocity at a specific destination on the surface while keeping stresses on the vehicle and any occupants within safe limits.

What are the basic shapes used in designing entry vehicles?

Several basic shapes are employed, including spheres or spherical sections, sphere-cones, biconics, and non-axisymmetric shapes like wings or lifting bodies.

Why was the spherical section shape commonly used for early crewed capsules?

The spherical section was favored because its aerodynamics and heat flux were relatively easy to model analytically using Newtonian impact theory and the Fay-Riddell equation. Its amenability to closed-form analysis made it a conservative design choice when high-speed computers were less available.

How did the Apollo command module achieve cross-range control using its spherical section shape?

The Apollo command module flew at a specific angle of attack, creating aerodynamic lift. By rolling the capsule along its longitudinal axis, this lift force could be directed left or right, allowing for control over the landing site.

What is a biconic shape, and how does it compare to a sphere-cone?

A biconic shape is essentially a sphere-cone with an additional frustum attached. This design offers a significantly improved lift-to-drag (L/D) ratio compared to a sphere-cone, making it more suitable for missions requiring greater maneuverability, such as transporting humans to Mars.

What are the two main sources of heating during atmospheric entry?

The primary sources of heating are convection, which is the transfer of heat from hot gas flowing past the object's surface, and radiation from the energetic shock layer that forms in front of the object.

How does the dominance of convective versus radiative heating change with velocity?

As velocity increases, both convective and radiative heating rise, but radiative heating increases at a much faster rate (proportional to the eighth power of velocity) compared to convective heating (proportional to the third power). Consequently, radiative heating dominates at very high speeds, while convection is more significant in the later stages of entry.

What is a 'radio-blackout' phenomenon during atmospheric entry?

A radio-blackout can occur during atmospheric entry when the intense ionization of the air in the shock layer interferes with radio communications between the spacecraft and the ground.

What are the four basic physical models used to describe the gas in the shock layer during reentry?

The four models are the perfect gas model, the real (equilibrium) gas model, the real (non-equilibrium) gas model, and the frozen gas model. Each model accounts for different aspects of gas behavior, such as dissociation, ionization, and reaction rates at high temperatures.

Under what conditions does the perfect gas model become inaccurate for reentry calculations?

The perfect gas model, which assumes the gas is chemically inert, begins to break down at temperatures above approximately 550 K (1000 K at one atmosphere) and is unusable at temperatures exceeding 2,000 K. At these higher temperatures, real gas effects become significant.

What is the significance of the Fay-Riddell equation in atmospheric entry?

The Fay-Riddell equation is important for modeling heat flux, particularly at the stagnation point of an entry vehicle. Its validity relies on the assumption that the gas at the stagnation point reaches chemical equilibrium, which is often the case due to the high pressures and temperatures involved.

What is a 'thermal protection system' (TPS)?

A thermal protection system, or TPS, is the barrier designed to shield a spacecraft from the extreme heat generated during atmospheric reentry. These systems can be ablative (sacrificial) or reusable.

How does an ablative heat shield protect a spacecraft?

An ablative heat shield works by charring, melting, or sublimating its surface material, lifting hot gases away from the vehicle's wall. This process, along with the expulsion of pyrolysis gases, creates a cooler boundary layer that blocks heat transfer.

What is carbon phenolic, and where has it been used?

Carbon phenolic is a dense, effective ablative material originally developed for rocket nozzle throats and nose tips. It was used as the Thermal Protection System (TPS) material for the Galileo Probe's heat shield.

What is PICA (Phenolic-impregnated carbon ablator), and what are its advantages?

PICA is a modern TPS material made from carbon fiber impregnated with phenolic resin. Its advantages include low density and efficient ablative capability, making it suitable for high-peak-heating conditions, such as those encountered on sample-return missions like Stardust.

What is PICA-X, and who developed it?

PICA-X is an improved and more cost-effective version of PICA, developed by SpaceX. It was used for the Dragon space capsule's heat shield and is significantly less expensive to manufacture than the original NASA PICA material.

What are refractory insulation TPS materials, and what are their characteristics?

Refractory insulation materials are used to keep heat contained within the outermost layer of a spacecraft's surface. They require very high melting points and low thermal conductivity, often being fabricated as tiles due to their brittleness and difficulty in large-scale production. The Space Shuttle used such tiles.

What is passively cooled TPS, and what materials were used in early designs?

Passively cooled TPS, also known as radiatively cooled TPS, absorbs heat flux during reentry and then radiates or convects the stored heat back into the atmosphere after the main heat pulse. Early designs, like those for the Mercury spacecraft, used significant amounts of metal like titanium or beryllium for this purpose.

What is reinforced carbon-carbon (RCC), and what were its applications on the Space Shuttle?

Reinforced carbon-carbon (RCC) is a radiatively cooled TPS material used on the Space Shuttle's nose cone and wing leading edges. It is chosen for its high temperature resistance, as carbon has a very high sublimation temperature.

What are Ultra-High Temperature Ceramics (UHTCs), and what potential do they offer?

UHTCs, such as those based on zirconium diboride and hafnium diboride, are advanced radiatively cooled TPS materials. They offer improved performance, allowing for sustained high-Mach number flight and enabling sharper leading edges to reduce drag, potentially revolutionizing hypersonic vehicle design.

What is actively cooled TPS, and how does it work?

Actively cooled TPS involves heat shields made from temperature-resistant materials with a circulating refrigerant or cryogenic fuel flowing through them. This system actively removes heat from the shield's surface.

How can propulsive entry aid in slowing down a spacecraft?

Using engine burns during entry, known as propulsive entry, can significantly slow down a vehicle much faster than atmospheric drag alone. It also has the effect of pushing the compressed, hot air away from the vehicle's body.

What is the 'feathered configuration' used by SpaceShipOne?

The feathered configuration involves rotating SpaceShipOne's wings upward to create a shuttlecock-like shape. This dramatically increases aerodynamic drag for reentry, allowing the vehicle to slow down efficiently at higher altitudes without experiencing extreme thermal loads.

Who developed the concept of feathered reentry, and what was the proposed application?

Dean R. Chapman of NACA first described feathered reentry in 1958. He proposed it as a 'composite entry' method, where an object might first enter with high drag, and then retract or jettison the drag device to transition to a lifting trajectory for maneuverability.

What is an inflatable heat shield, and what advantage does it offer?

An inflatable heat shield is a low-mass design that can significantly enlarge the 'drag area' of an entry system. This is beneficial for deceleration, especially for higher-speed missions like Mars returns, as a larger drag area allows for greater payload capacity.

What were the key design considerations for entry vehicles?

Four critical parameters guide entry vehicle design: peak heat flux, total heat load, peak deceleration (especially for crewed missions), and peak dynamic pressure. These factors influence the choice of TPS material, thickness, and overall vehicle shape.

How do 'overshoot' and 'undershoot' trajectories influence entry vehicle design?

The 'overshoot' trajectory (shallowest entry angle) typically dictates the required thickness of the Thermal Protection System (TPS) due to the higher heat load. The 'undershoot' trajectory (steepest entry angle) determines the TPS material selection based on peak heat flux and dynamic pressure, and limits peak deceleration for crewed missions.

What limits the maximum bluntness of an entry vehicle's shape?

The maximum bluntness is limited by aerodynamic stability considerations related to shock wave detachment. If a cone's half-angle is too large (e.g., over ~60 degrees for Earth's atmosphere), the shock wave detaches, leading to instability.

What are some examples of atmospheric entry accidents where the crew survived?

Notable incidents where crews survived despite reentry issues include Voskhod 2 and Soyuz 5 (service module detachment problems), Apollo 15 (parachute malfunction), Space Shuttle Columbia's first flight (STS-1, damage during reentry), and Soyuz TMA-11 (ballistic reentry due to separation issues).

What were some catastrophic atmospheric entry accidents?

Catastrophic failures resulting in fatalities include Soyuz 1 (parachute entanglement during emergency landing), Soyuz 11 (depressurization before reentry), and Space Shuttle Columbia's STS-107 mission (wing leading edge failure causing breakup).

What percentage of a satellite's mass typically survives reentry and reaches the Earth's surface?

Approximately 10% to 40% of an object's mass may survive atmospheric reentry and reach the Earth's surface.

What happened when Kosmos 954 reentered Earth's atmosphere?

The Soviet satellite Kosmos 954, weighing 3,800 kg, reentered in 1978 and crashed near Great Slave Lake in Canada, scattering radioactive debris across the impact area.

What was the Skylab space station's reentry fate?

In 1979, the Skylab space station, weighing approximately 77,100 kg, reentered Earth's atmosphere and dispersed debris across the Australian Outback. NASA had hoped to use the Space Shuttle to control its descent, but program delays prevented this.

What environmental impact can spacecraft reentry have on Earth's atmosphere?

Atmospheric entry, particularly from the increasing number of satellites, contributes artificial aerosols to the atmosphere. These pollutants can react with and potentially negatively impact atmospheric composition, including the ozone layer.

Atmospheric Entry Wiki: Ascent Through the Inferno: Understanding Atmospheric Entry

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The Phenomenon of Entry

Defining Atmospheric Entry

Atmospheric entry signifies the passage of an object from the vacuum of outer space into and through the gaseous envelope of a celestial body, such as a planet, dwarf planet, or natural satellite. This process can be either uncontrolled, as with astronomical objects and space debris, or controlled, as in the case of spacecraft utilizing specific Entry, Descent, and Landing (EDL) procedures.

The Physics of Entry

Objects engaging in atmospheric entry encounter significant forces, primarily atmospheric drag and aerodynamic heating. Aerodynamic heating is predominantly caused by the compression of atmospheric gases ahead of the object, though drag itself also contributes. These forces can lead to mass loss through ablation or even complete structural failure for smaller or less robust objects.

Velocity and Energy Dissipation

Objects typically enter atmospheres at extremely high velocities, ranging from orbital speeds (approximately 7.8 km/s) to hyperbolic escape velocities (around 11.2 km/s or higher). Dissipating this immense kinetic energy through atmospheric interaction is the primary challenge, as using retrorockets for the entire deceleration process is often impractical due to fuel constraints.

Historical Development

Early Concepts and Discoveries

The foundational concept of using ablative heat shields was articulated by Robert Goddard as early as 1920. He theorized that layered, infusible materials could protect against the intense heating experienced by meteors. Practical development accelerated with the increasing range and reentry velocities of ballistic missiles, where managing aerodynamic stress and thermal loads became critical.

The Blunt Body Revolution

In the 1950s, NACA researchers H. Julian Allen and A. J. Eggers Jr. made a pivotal discovery: blunt-shaped vehicles, despite seeming counterintuitive, were more effective heat shields. This was because a blunt shape creates a strong shock wave, pushing the superheated gas layer away from the vehicle, thereby reducing the heat flux experienced by the spacecraft.

The principle behind blunt-body reentry is that the air's inability to move out of the way quickly enough creates a cushion of hot gas ahead of the vehicle. This shock layer, while extremely hot, is largely kept separate from the vehicle's surface, minimizing convective and radiative heat transfer. This counterintuitive finding revolutionized reentry vehicle design, leading to the adoption of spherical and sphere-cone shapes for many early spacecraft.

Evolution in Space Exploration

From the early capsules like Vostok and Mercury, which utilized spherical section heat shields, to the lifting bodies of the Space Shuttle and modern designs like SpaceX's Starship, the evolution of entry vehicle shapes and thermal protection systems has been continuous. Each mission and technological advancement has refined our understanding and capability in navigating these critical atmospheric transitions.

Key Terminology

Entry, Descent, and Landing (EDL)

This collective term refers to the sequence of events involved in safely landing a spacecraft on a celestial body's surface after atmospheric entry. It encompasses all phases from initial atmospheric interface to final touchdown.

Reentry

Specifically refers to the atmospheric entry of a spacecraft returning to the same celestial body from which it originated, most commonly associated with Earth return missions.

Thermal Protection System (TPS)

The critical barrier designed to shield a spacecraft from the extreme temperatures generated during atmospheric entry. TPS can be ablative, reusable, actively cooled, or passively cooled.

Ablation

A process where the surface material of a heat shield gradually burns away, melts, or vaporizes. This sacrificial process absorbs heat and carries it away from the spacecraft, protecting the underlying structure.

Entry Vehicle Geometries

Sphere or Spherical Section

The simplest axisymmetric shape, often used in early capsules like Vostok and Mercury. While providing high drag, they offer minimal lift, limiting cross-range capability. Flying at an angle of attack can induce some lift.

Sphere-Cone

A combination of a spherical section forebody and a conical afterbody. This design offers improved stability and was widely adopted for ballistic missile reentry vehicles (e.g., Mk-6) and early space exploration missions (e.g., Apollo Command Module, Soyuz).

Biconic

Features an additional frustum attached to a sphere-cone, significantly enhancing the Lift-to-Drag (L/D) ratio. This allows for greater maneuverability and reduced deceleration loads, making it suitable for missions requiring precise landing site control or crewed flights (e.g., AMaRV, DC-X).

Non-Axisymmetric Shapes

Winged vehicles (like the Space Shuttle, Buran, Starship) or lifting bodies utilize non-axisymmetric designs. These shapes provide substantial aerodynamic lift, enabling glider-like maneuvering during descent, but often involve more complex TPS requirements.

Understanding Entry Heating

Sources of Heat

Atmospheric entry heating arises primarily from two mechanisms: convective heat transfer from the hot gas flowing over the vehicle's surface, and radiative heat transfer from the intensely hot plasma generated in the shock layer formed ahead of the vehicle.

Velocity Dependence

Both convective and radiative heating increase with velocity, but at different rates. Radiative heating escalates dramatically with velocity (proportional to V⁸), becoming dominant at higher speeds, while convective heating increases more gradually (proportional to V³).

Gas Physics Models

Accurate modeling of the shock layer gas is crucial. This involves understanding the behavior of gases at extreme temperatures, including dissociation and ionization. Models range from the simplified perfect gas model to more complex real gas models (equilibrium and non-equilibrium) that account for chemical reactions and thermodynamic states.

Perfect Gas Model: Assumes inert gas, useful for lower temperatures but breaks down above ~2000 K.

Real (Equilibrium) Gas Model: Assumes gases react and reach thermodynamic equilibrium. Useful when reactions have time to complete, like at the stagnation point.

Real (Non-equilibrium) Gas Model: Accounts for the time-dependent nature of chemical reactions. Essential for accurate modeling, especially at high speeds and varying pressures, requiring complex computational fluid dynamics (CFD).

Frozen Gas Model: A special case where chemical reactions cease due to rapid expansion, "freezing" the gas composition.

Thermal Protection Systems (TPS)

Ablative TPS

Materials designed to char, melt, or sublimate, carrying heat away. Examples include carbon phenolic (dense, effective for high heat flux) and PICA/PICA-X (lighter, efficient for high heat flux, used on Stardust and Dragon).

Carbon Phenolic: Robust, high-density material used for nose tips and high heat flux applications (e.g., Galileo Probe).
SLA-561V: Lighter ablator used on Mars missions like Mars Pathfinder and MER.
PICA (Phenolic-Impregnated Carbon Ablator): Low-density, efficient material for high-speed reentry (e.g., Stardust).
PICA-X: An improved, cost-effective version developed by SpaceX for Dragon.
AVCOAT: Developed by NASA, used on Apollo and Orion spacecraft.

Reusable TPS

Typically consists of refractory insulation tiles that withstand high temperatures and have low thermal conductivity. The Space Shuttle's silica tiles (e.g., LI-900) are a prime example, though they are brittle.

Space Shuttle Tiles: Silica-based tiles (LI-900, LI-2200) offering excellent insulation but requiring careful handling.
Reinforced Carbon-Carbon (RCC): Used on the Shuttle's wing leading edges and nose cap for extreme temperatures, though expensive and heavy.
Ultra-High Temperature Ceramics (UHTCs): Materials like Zirconium Diboride and Hafnium Diboride, offering high strength and temperature resistance for sharp leading edges.

Active & Passive Cooling

Passive Cooling: Relies on radiative properties (High Emissivity Coatings - HECs) or thermal mass to manage heat. Early designs used metal surfaces.

Active Cooling: Involves circulating coolants (like cryogenic fuel or water) through channels within the heat shield structure. This is complex but potentially lighter and more robust for certain applications.

Entry Mishaps & Disasters

Uncontrolled Reentries

Objects like satellites (Kosmos 954, Skylab, Tiangong-1) and rocket stages can reenter uncontrollably. While most burn up, surviving debris can pose risks. Controlled deorbiting is preferred to mitigate these dangers.

Mission Failures

Several missions have experienced critical failures during entry, descent, or landing due to technical issues, design flaws, or human error. Examples include Mars Polar Lander, Genesis, Soyuz TMA-11 (ballistic reentry), and the tragic losses of Soyuz 1, Soyuz 11, and Space Shuttle Columbia (STS-107).

Voskhod 2 / Soyuz 5: Service module separation issues, crew survived.
Apollo 15: Parachute malfunction, crew survived.
Genesis: Parachute failure due to G-switch error, vehicle crashed.
Soyuz TMA-11: Propulsion module separation issue leading to ballistic reentry and high G-forces.
STS-107 Columbia: TPS damage from launch debris caused catastrophic breakup during reentry.
Mars Polar Lander: Believed software error caused loss during EDL.

Environmental Considerations

The increasing number of satellite reentries raises concerns about atmospheric pollution. Burning spacecraft release chemicals that can potentially impact the ozone layer. Space sustainability initiatives are exploring cleaner materials and in-orbit servicing to mitigate these effects.

Atmospheric Impact

Pollutants and Stratosphere

Atmospheric entry, particularly from the increasing number of satellites, contributes to atmospheric pollution, especially in the stratosphere. The burning of spacecraft releases various chemicals, including metallic oxides and combustion byproducts, which can potentially affect atmospheric composition and the ozone layer.

Space Sustainability

As artificial entries become more prevalent, space sustainability is a growing concern. Current practices focus on controlled deorbiting to prevent uncontrolled debris impacts. Future strategies may involve using less polluting materials and developing in-orbit servicing or recycling capabilities.

Visualizing Entry

Reentry Trails

The intense heat generated during atmospheric entry ionizes the surrounding air, creating visible plasma trails. These trails are often captured in photographs and videos, providing visual evidence of the extreme conditions vehicles endure.

Capsule Designs

Images of various spacecraft capsules, such as Apollo, Soyuz, and Dragon, showcase the diverse range of shapes and thermal protection systems developed for atmospheric entry across different eras and missions.

Heat Shield Views

Close-up views of heat shields after reentry reveal the effects of ablation and thermal stress, demonstrating the effectiveness of the materials used to protect the spacecraft from the fiery passage through the atmosphere.

Further Exploration

Related Concepts

Explore related fields such as Aerocapture, Hypersonic Flight, Orbital Mechanics, and the design principles behind various spacecraft types like Space Capsules and Landers.

Key Technologies

Investigate critical technologies like heat shields, ablative materials, computational fluid dynamics (CFD), and advanced materials science that enable successful atmospheric entry.

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References

Parker, John and C. Michael Hogan, "Techniques for Wind Tunnel assessment of Ablative Materials", NASA Ames Research Center, Technical Publication, August, 1965.

Tran, Huy K, et al., "Qualification of the forebody heat shield of the Stardust's Sample Return Capsule", AIAA, Thermophysics Conference, 32nd, Atlanta, GA; 23â25 June 1997.

Tran, Huy K., et al., "Silicone impregnated reusable ceramic ablators for Mars follow-on missions," AIAA-1996-1819, Thermophysics Conference, 31st, New Orleans, June 17â20, 1996.

A full list of references for this article are available at the Atmospheric entry Wikipedia page

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This page was generated by an Artificial Intelligence and is intended for informational and educational purposes only. The content is based on a snapshot of publicly available data from Wikipedia and may not be entirely accurate, complete, or up-to-date.

This is not professional aerospace engineering advice. The information provided on this website is not a substitute for professional consultation, analysis, or design work. Always refer to official technical documentation, consult with qualified aerospace engineers, and adhere to rigorous safety protocols for any real-world application.

The creators of this page are not responsible for any errors or omissions, or for any actions taken based on the information provided herein.

Ascent Through the Inferno

💡 Dive in with Flashcard Learning! 💡

The Phenomenon of Entry 🌌

🚀 Defining Atmospheric Entry

🔥 The Physics of Entry

⚡ Velocity and Energy Dissipation

Historical Development 📜

💡 Early Concepts and Discoveries

🚀 The Blunt Body Revolution

🛰️ Evolution in Space Exploration

Key Terminology 🗂️

➡️ Entry, Descent, and Landing (EDL)

🔄 Reentry

🌡️ Thermal Protection System (TPS)

💨 Ablation

Entry Vehicle Geometries 📐

⚪ Sphere or Spherical Section

🍦 Sphere-Cone

🔺 Biconic

✈️ Non-Axisymmetric Shapes

Understanding Entry Heating 🔥

♨️ Sources of Heat

📈 Velocity Dependence

⚛️ Gas Physics Models

Thermal Protection Systems (TPS) 🛡️

🔥 Ablative TPS

⬜ Reusable TPS

💧 Active & Passive Cooling

Entry Mishaps & Disasters ⚠️

💥 Uncontrolled Reentries

❌ Mission Failures

🌍 Environmental Considerations

Atmospheric Impact ☁️

🏭 Pollutants and Stratosphere

⚖️ Space Sustainability

Visualizing Entry 🖼️

☄️ Reentry Trails

🛰️ Capsule Designs

🔥 Heat Shield Views

Further Exploration 🔗

🚀 Related Concepts

💡 Key Technologies

Teacher's Corner 🧑‍🏫

Edit and Print this course in the Wiki2Web Teacher Studio

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Disclaimer ⚠️

📜 Important Notice

Dive in with Flashcard Learning!

The Phenomenon of Entry

Defining Atmospheric Entry

The Physics of Entry

Velocity and Energy Dissipation

Historical Development

Early Concepts and Discoveries

The Blunt Body Revolution

Evolution in Space Exploration

Key Terminology

Entry, Descent, and Landing (EDL)

Reentry

Thermal Protection System (TPS)

Ablation

Entry Vehicle Geometries

Sphere or Spherical Section

Sphere-Cone

Biconic

Non-Axisymmetric Shapes

Understanding Entry Heating

Sources of Heat

Velocity Dependence

Gas Physics Models

Thermal Protection Systems (TPS)

Ablative TPS

Reusable TPS

Active & Passive Cooling

Entry Mishaps & Disasters

Uncontrolled Reentries

Mission Failures

Environmental Considerations

Atmospheric Impact

Pollutants and Stratosphere

Space Sustainability

Visualizing Entry

Reentry Trails

Capsule Designs

Heat Shield Views

Further Exploration

Related Concepts

Key Technologies

Teacher's Corner

True or False?

Test Your Knowledge!

Gamer's Corner

Discover other topics to study!

References

Feedback & Support

Disclaimer

Important Notice