Atmospheric reentry - Introduction

The technology of atmospheric reentry was a consequence of the Cold War. Ballistic missiles and nuclear weapons were legacies of World War II left to both the Soviet Union and the United States. Both nations initiated massive research and development programs to further the military capability of those technologies. However before a missile delivered nuclear weapon could be practical there lacked an essential ingredient: an atmospheric reentry technology. In theory, the nation first developing a reentry technology had a decisive milit ...

Including:

• Atmospheric reentry - Introduction
• Atmospheric reentry - Terminology definitions and jargon
• Atmospheric reentry - Blunt body entry vehicles
• Atmospheric reentry - Entry vehicle shapes
• Atmospheric reentry - Shock layer gas physics
• Atmospheric reentry - Ablative heat shields
• Atmospheric reentry - Thermal soak heat shields
• Atmospheric reentry - Passively cooled heat shields
• Atmospheric reentry - Actively cooled heat shields
• Atmospheric reentry - Feathered reentry
• Atmospheric reentry - Entry vehicle design considerations
• Atmospheric reentry - History's most difficult atmospheric entry
• Atmospheric reentry - Notable atmospheric entry mishaps
• Atmospheric reentry - Uncontrolled reentry
• Atmospheric reentry - Reference books
• Atmospheric reentry - Commentary about the reference books

Read more here: » Atmospheric reentry: Encyclopedia - Atmospheric reentry

Over the decades since the 1950s, a rich technical jargon has grown around the engineering of vehicles designed to enter planetary atmospheres. Definition of the jargon is prerequisite to meaningful discussion about atmospheric reentry. Atmospheric entry is the transition from the vacuum of space to the atmosphere of any planet or other celestial body. The term is not used for landing on bodies which have no atmosphere such as the Moon. Atmospheric reentry refers to the return to an atmosphere previously left for ...

See also:

Atmospheric reentry, Atmospheric reentry - Introduction, Atmospheric reentry - Terminology, definitions and jargon, Atmospheric reentry - Blunt body entry vehicles, Atmospheric reentry - Entry vehicle shapes, Atmospheric reentry - Shock layer gas physics, Atmospheric reentry - Ablative heat shields, Atmospheric reentry - Thermal soak heat shields, Atmospheric reentry - Passively cooled heat shields, Atmospheric reentry - Actively cooled heat shields, Atmospheric reentry - Feathered reentry, Atmospheric reentry - Entry vehicle design considerations, Atmospheric reentry - History's most difficult atmospheric entry, Atmospheric reentry - Notable atmospheric entry mishaps, Atmospheric reentry - Uncontrolled reentry, Atmospheric reentry - Reference books, Atmospheric reentry - Commentary about the reference books

Read more here: » Atmospheric reentry: Encyclopedia II - Atmospheric reentry - Terminology, definitions and jargon

The technology of atmospheric reentry was a consequence of the Cold War. Ballistic missiles and nuclear weapons were legacies of World War II left to both the Soviet Union and the United States. Both nations initiated massive research and development programs to further the military capability of those technologies. However before a missile delivered nuclear weapon could be practical there lacked an essential ingredient: an atmospheric reentry technology. In theory, the nation first developing a reentry technology had a decisive milit ...

See also:

Atmospheric reentry, Atmospheric reentry - Introduction, Atmospheric reentry - Terminology definitions and jargon, Atmospheric reentry - Blunt body entry vehicles, Atmospheric reentry - Entry vehicle shapes, Atmospheric reentry - Shock layer gas physics, Atmospheric reentry - Ablative heat shields, Atmospheric reentry - Thermal soak heat shields, Atmospheric reentry - Passively cooled heat shields, Atmospheric reentry - Actively cooled heat shields, Atmospheric reentry - Feathered reentry, Atmospheric reentry - Entry vehicle design considerations, Atmospheric reentry - History's most difficult atmospheric entry, Atmospheric reentry - Notable atmospheric entry mishaps, Atmospheric reentry - Uncontrolled reentry, Atmospheric reentry - Reference books, Atmospheric reentry - Commentary about the reference books

Read more here: » Atmospheric reentry: Encyclopedia II - Atmospheric reentry - Introduction

Over the decades since the 1950s, a rich technical jargon has grown around the engineering of vehicles designed to enter planetary atmospheres. Definition of the jargon is prerequisite to meaningful discussion about atmospheric reentry. Atmospheric entry is the transition from the vacuum of space to the atmosphere of any planet or other celestial body. The term is not used for landing on bodies which have no atmosphere such as the Moon. Atmospheric reentry refers to the return to an atmosphere previously left for ...

See also:

Atmospheric reentry, Atmospheric reentry - Introduction, Atmospheric reentry - Terminology definitions and jargon, Atmospheric reentry - Blunt body entry vehicles, Atmospheric reentry - Entry vehicle shapes, Atmospheric reentry - Shock layer gas physics, Atmospheric reentry - Ablative heat shields, Atmospheric reentry - Thermal soak heat shields, Atmospheric reentry - Passively cooled heat shields, Atmospheric reentry - Actively cooled heat shields, Atmospheric reentry - Feathered reentry, Atmospheric reentry - Entry vehicle design considerations, Atmospheric reentry - History's most difficult atmospheric entry, Atmospheric reentry - Notable atmospheric entry mishaps, Atmospheric reentry - Uncontrolled reentry, Atmospheric reentry - Reference books, Atmospheric reentry - Commentary about the reference books

Read more here: » Atmospheric reentry: Encyclopedia II - Atmospheric reentry - Terminology definitions and jargon

In 2004, aircraft designer Burt Rutan demonstrated the feasibility of an alternative or complementary approach to atmospheric reentry with the suborbital SpaceShipOne. SpaceShipOne has what has been described as a pair of flipping wings; the spacecraft itself changes shape for reentry. This increases drag, as the craft is now less streamlined. This results in more atmospheric gas particles hitting the spacecraft at higher altitudes than otherwise. The aircraft thus slows down more in higher atmospheric layers (which is the very ...

See also:

Atmospheric reentry, Atmospheric reentry - Introduction, Atmospheric reentry - Terminology definitions and jargon, Atmospheric reentry - Blunt body entry vehicles, Atmospheric reentry - Entry vehicle shapes, Atmospheric reentry - Shock layer gas physics, Atmospheric reentry - Ablative heat shields, Atmospheric reentry - Thermal soak heat shields, Atmospheric reentry - Passively cooled heat shields, Atmospheric reentry - Actively cooled heat shields, Atmospheric reentry - Feathered reentry, Atmospheric reentry - Entry vehicle design considerations, Atmospheric reentry - History's most difficult atmospheric entry, Atmospheric reentry - Notable atmospheric entry mishaps, Atmospheric reentry - Uncontrolled reentry, Atmospheric reentry - Reference books, Atmospheric reentry - Commentary about the reference books

Read more here: » Atmospheric reentry: Encyclopedia II - Atmospheric reentry - Feathered reentry

There are four critical parameters considered when designing a vehicle for atmospheric entry: Peak heat flux Heat load Peak deceleration Peak dynamic pressure Peak heat flux selects the TPS material. Heat load selects the thickness of the TPS material stack. Peak deceleration is of major importance for manned missions. The upper limit for manned return to Earth from Low Earth Orbit (LEO) or lunar return is 10 G. For martian atmospheric entry after long exposure to zero gravity, the upper limit is 4 G. Peak dynamic pressure can also influ ...

See also:

Atmospheric reentry, Atmospheric reentry - Introduction, Atmospheric reentry - Terminology definitions and jargon, Atmospheric reentry - Blunt body entry vehicles, Atmospheric reentry - Entry vehicle shapes, Atmospheric reentry - Shock layer gas physics, Atmospheric reentry - Ablative heat shields, Atmospheric reentry - Thermal soak heat shields, Atmospheric reentry - Passively cooled heat shields, Atmospheric reentry - Actively cooled heat shields, Atmospheric reentry - Feathered reentry, Atmospheric reentry - Entry vehicle design considerations, Atmospheric reentry - History's most difficult atmospheric entry, Atmospheric reentry - Notable atmospheric entry mishaps, Atmospheric reentry - Uncontrolled reentry, Atmospheric reentry - Reference books, Atmospheric reentry - Commentary about the reference books

Read more here: » Atmospheric reentry: Encyclopedia II - Atmospheric reentry - Entry vehicle design considerations

Martin, John J., "Atmospheric Entry - An Introduction to Its Science ane Engineering," Prentice-Hall, Old Tappan, NJ, (1966). Regan, Frank J., "Re-Entry Vehicle Dynamics," AIAA Education Series, American Institute of Aeronautics and Astronautics, Inc., New York, ISBN 0-915928-78-7, (1984). Regan, Frank J. and Anadakrishnan, Satya M., "Dynamics of Atmospheric Re-Entry," AIAA Education Series, American Institute of Aeronautics and Astronautics, Inc., New York, ISBN 1-56347-048-9, (1993). Etkin, Bernard, "Dynamics of Atmospheric Flight," John Wiley ...

See also:

Atmospheric reentry, Atmospheric reentry - Introduction, Atmospheric reentry - Terminology definitions and jargon, Atmospheric reentry - Blunt body entry vehicles, Atmospheric reentry - Entry vehicle shapes, Atmospheric reentry - Shock layer gas physics, Atmospheric reentry - Ablative heat shields, Atmospheric reentry - Thermal soak heat shields, Atmospheric reentry - Passively cooled heat shields, Atmospheric reentry - Actively cooled heat shields, Atmospheric reentry - Feathered reentry, Atmospheric reentry - Entry vehicle design considerations, Atmospheric reentry - History's most difficult atmospheric entry, Atmospheric reentry - Notable atmospheric entry mishaps, Atmospheric reentry - Uncontrolled reentry, Atmospheric reentry - Reference books, Atmospheric reentry - Commentary about the reference books

Read more here: » Atmospheric reentry: Encyclopedia II - Atmospheric reentry - Reference books

Various advanced reusable spacecraft and hypersonic aircraft designs have been proposed to employ heat shields made from temperature-resistant metal alloys that incorporated a refrigerant or cryogenic fuel circulating through them. Such a TPS concept was proposed for the X-30 National Aerospace Plane (NASP). The NASP was supposed to have been a scramjet powered hypersonic aircraft but failed in development. In the early 1960s various TPS systems were proposed to use water or other cooling liquid sprayed into the shock layer. Such concepts never got past the proposal phase s ...

See also:

Atmospheric reentry, Atmospheric reentry - Introduction, Atmospheric reentry - Terminology definitions and jargon, Atmospheric reentry - Blunt body entry vehicles, Atmospheric reentry - Entry vehicle shapes, Atmospheric reentry - Shock layer gas physics, Atmospheric reentry - Ablative heat shields, Atmospheric reentry - Thermal soak heat shields, Atmospheric reentry - Passively cooled heat shields, Atmospheric reentry - Actively cooled heat shields, Atmospheric reentry - Feathered reentry, Atmospheric reentry - Entry vehicle design considerations, Atmospheric reentry - History's most difficult atmospheric entry, Atmospheric reentry - Notable atmospheric entry mishaps, Atmospheric reentry - Uncontrolled reentry, Atmospheric reentry - Reference books, Atmospheric reentry - Commentary about the reference books

Read more here: » Atmospheric reentry: Encyclopedia II - Atmospheric reentry - Actively cooled heat shields

There are several basic shapes used in designing entry vehicles: The simplist axisymmetric shape is the spherical section. The spherical section's aerodynamics are easy to model analytically using Newtonian impact theory. Likewise, the spherical section's heat flux can be accurately modelled with the Fay-Riddell equation. The static stability of a spherical section is assured if the vehicle's center-of-mass is upstream from the center-of-curvature (dynamic stability is more problematic). By flying at an angle-of-attack, a spher ...

See also:

Atmospheric reentry, Atmospheric reentry - Introduction, Atmospheric reentry - Terminology definitions and jargon, Atmospheric reentry - Blunt body entry vehicles, Atmospheric reentry - Entry vehicle shapes, Atmospheric reentry - Shock layer gas physics, Atmospheric reentry - Ablative heat shields, Atmospheric reentry - Thermal soak heat shields, Atmospheric reentry - Passively cooled heat shields, Atmospheric reentry - Actively cooled heat shields, Atmospheric reentry - Feathered reentry, Atmospheric reentry - Entry vehicle design considerations, Atmospheric reentry - History's most difficult atmospheric entry, Atmospheric reentry - Notable atmospheric entry mishaps, Atmospheric reentry - Uncontrolled reentry, Atmospheric reentry - Reference books, Atmospheric reentry - Commentary about the reference books

Read more here: » Atmospheric reentry: Encyclopedia II - Atmospheric reentry - Entry vehicle shapes

These four shadowgraph images represent early re-entry vehicle concepts. A shadowgraph is a process that makes visible the disturbances that occur in a fluid flow at high velocity, in which light passing through a flowing fluid is refracted by the density gradients in the fluid resulting in bright and dark areas on a screen placed behind the fluid. H. Julian Allen and A. J. Eggers, Jr. of the National Advisory Committee for Aeronautics (NACA) made the counter-intuitive discovery in 1952 that a blunt shape (high drag) made the most eff ...

See also:

Atmospheric reentry, Atmospheric reentry - Introduction, Atmospheric reentry - Terminology definitions and jargon, Atmospheric reentry - Blunt body entry vehicles, Atmospheric reentry - Entry vehicle shapes, Atmospheric reentry - Shock layer gas physics, Atmospheric reentry - Ablative heat shields, Atmospheric reentry - Thermal soak heat shields, Atmospheric reentry - Passively cooled heat shields, Atmospheric reentry - Actively cooled heat shields, Atmospheric reentry - Feathered reentry, Atmospheric reentry - Entry vehicle design considerations, Atmospheric reentry - History's most difficult atmospheric entry, Atmospheric reentry - Notable atmospheric entry mishaps, Atmospheric reentry - Uncontrolled reentry, Atmospheric reentry - Reference books, Atmospheric reentry - Commentary about the reference books

Read more here: » Atmospheric reentry: Encyclopedia II - Atmospheric reentry - Blunt body entry vehicles

An approximate rule-of-thumb used by heat shield designers for estimating peak shock layer temperature is to assume the air temperature in kelvins to be equal to the entry speed in meters per second. For example, a spacecraft entering the atmosphere at 7.8 km/s would experience a peak shock layer temperature of 7800 K. This method of estimation is a mathematical accident and a consequence of peak heat flux ...

See also:

Atmospheric reentry, Atmospheric reentry - Introduction, Atmospheric reentry - Terminology definitions and jargon, Atmospheric reentry - Blunt body entry vehicles, Atmospheric reentry - Entry vehicle shapes, Atmospheric reentry - Shock layer gas physics, Atmospheric reentry - Ablative heat shields, Atmospheric reentry - Thermal soak heat shields, Atmospheric reentry - Passively cooled heat shields, Atmospheric reentry - Actively cooled heat shields, Atmospheric reentry - Feathered reentry, Atmospheric reentry - Entry vehicle design considerations, Atmospheric reentry - History's most difficult atmospheric entry, Atmospheric reentry - Notable atmospheric entry mishaps, Atmospheric reentry - Uncontrolled reentry, Atmospheric reentry - Reference books, Atmospheric reentry - Commentary about the reference books

Read more here: » Atmospheric reentry: Encyclopedia II - Atmospheric reentry - Shock layer gas physics

The type of heat shield that best protects against high heat flux is the ablative heat shield. The ablative heat shield functions by lifting the hot shock layer gas away from the heat shield's outer wall (creating a cooler boundary layer) through blowing. The overall process of reducing the heat flux experienced by the heat shield's outer wall is called blockage. Ablation causes the TPS layer to char, melt, and sublimate through the process of pyrolysis. The gas produced by pyrolysis is what drives blowing and causes blo ...

See also:

Atmospheric reentry, Atmospheric reentry - Introduction, Atmospheric reentry - Terminology definitions and jargon, Atmospheric reentry - Blunt body entry vehicles, Atmospheric reentry - Entry vehicle shapes, Atmospheric reentry - Shock layer gas physics, Atmospheric reentry - Ablative heat shields, Atmospheric reentry - Thermal soak heat shields, Atmospheric reentry - Passively cooled heat shields, Atmospheric reentry - Actively cooled heat shields, Atmospheric reentry - Feathered reentry, Atmospheric reentry - Entry vehicle design considerations, Atmospheric reentry - History's most difficult atmospheric entry, Atmospheric reentry - Notable atmospheric entry mishaps, Atmospheric reentry - Uncontrolled reentry, Atmospheric reentry - Reference books, Atmospheric reentry - Commentary about the reference books

Read more here: » Atmospheric reentry: Encyclopedia II - Atmospheric reentry - Ablative heat shields

Thermal soak is a part of almost all TPS schemes. For example, an ablative heat shield loses most of its thermal protection effectiveness when the outer wall temperature drops below the minimum necessary for pyrolysis. From that time to the end of the heat pulse, heat from the shock layer soaks into the heat shield's outer wall and would eventually convect to the payload. This outcome is prevented by ejecting the heat shield (wi ...

See also:

Atmospheric reentry, Atmospheric reentry - Introduction, Atmospheric reentry - Terminology definitions and jargon, Atmospheric reentry - Blunt body entry vehicles, Atmospheric reentry - Entry vehicle shapes, Atmospheric reentry - Shock layer gas physics, Atmospheric reentry - Ablative heat shields, Atmospheric reentry - Thermal soak heat shields, Atmospheric reentry - Passively cooled heat shields, Atmospheric reentry - Actively cooled heat shields, Atmospheric reentry - Feathered reentry, Atmospheric reentry - Entry vehicle design considerations, Atmospheric reentry - History's most difficult atmospheric entry, Atmospheric reentry - Notable atmospheric entry mishaps, Atmospheric reentry - Uncontrolled reentry, Atmospheric reentry - Reference books, Atmospheric reentry - Commentary about the reference books

Read more here: » Atmospheric reentry: Encyclopedia II - Atmospheric reentry - Thermal soak heat shields

In some early ballistic missile RVs, e.g. the Mk-2 and the sub-orbital Mercury spacecraft, radiatively cooled TPS were used to initially store heat flux during the heat pulse and then latter radiate the heat away from the vehicle. However the technique required a considerable quantity of metal TPS (e.g. beryllium), adding greatly to the vehicle's mass. Consequently ablative and thermal soak TPS have been more common. Some high-velocity aircraft, such as the SR-71 Blackbird and Concorde, had to deal with heating similar to that ...

See also:

Atmospheric reentry, Atmospheric reentry - Introduction, Atmospheric reentry - Terminology definitions and jargon, Atmospheric reentry - Blunt body entry vehicles, Atmospheric reentry - Entry vehicle shapes, Atmospheric reentry - Shock layer gas physics, Atmospheric reentry - Ablative heat shields, Atmospheric reentry - Thermal soak heat shields, Atmospheric reentry - Passively cooled heat shields, Atmospheric reentry - Actively cooled heat shields, Atmospheric reentry - Feathered reentry, Atmospheric reentry - Entry vehicle design considerations, Atmospheric reentry - History's most difficult atmospheric entry, Atmospheric reentry - Notable atmospheric entry mishaps, Atmospheric reentry - Uncontrolled reentry, Atmospheric reentry - Reference books, Atmospheric reentry - Commentary about the reference books

Read more here: » Atmospheric reentry: Encyclopedia II - Atmospheric reentry - Passively cooled heat shields