Atmospheric pressure, also known as air pressure or barometric pressure, is the pressure within the atmosphere of Earth. The standard atmosphere is a unit of pressure defined as 101,325 Pa (1,013.25 hPa), which is equivalent to 1,013.25 millibars, 760 mm Hg, 29.9212 inches Hg, or 14.696 psi. The atm unit is roughly equivalent to the mean sea-level atmospheric pressure on Earth; that is, the Earth's atmospheric pressure at sea level is approximately 1 atm.
An aerobot is an aerial robot, usually used in the context of an unmanned space probe or unmanned aerial vehicle.
The atmosphere of Earth is the layer of gases, known collectively as air, retained by Earth's gravity that surrounds the planet and forms its planetary atmosphere. The atmosphere of Earth creates pressure, absorbs most meteoroids and ultraviolet solar radiation, warms the surface through heat retention, and reduces temperature extremes between day and night, maintaining conditions allowing life and liquid water to exist on the Earth's surface.
Buoyancy, or upthrust, is an upward force exerted by a fluid that opposes the weight of a partially or fully immersed object. In a column of fluid, pressure increases with depth as a result of the weight of the overlying fluid. Thus the pressure at the bottom of a column of fluid is greater than at the top of the column. Similarly, the pressure at the bottom of an object submerged in a fluid is greater than at the top of the object. The pressure difference results in a net upward force on the object. The magnitude of the force is proportional to the pressure difference, and is equivalent to the weight of the fluid that would otherwise occupy the submerged volume of the object, i.e. the displaced fluid.
An aerostat is a lighter-than-air aircraft that gains its lift through the use of a buoyant gas. Aerostats include unpowered balloons and powered airships. A balloon may be free-flying or tethered. The average density of the craft is lower than the density of atmospheric air, because its main component is one or more gasbags, a lightweight skin containing a lifting gas to provide buoyancy, to which other components such as a gondola containing equipment or people are attached. Especially with airships, the gasbags are often protected by an outer envelope.
In aeronautics, a balloon is an unpowered aerostat, which remains aloft or floats due to its buoyancy. A balloon may be free, moving with the wind, or tethered to a fixed point. It is distinct from an airship, which is a powered aerostat that can propel itself through the air in a controlled manner.
High-altitude balloons or stratostats are usually uncrewed balloons typically filled with helium or hydrogen and released into the stratosphere, generally attaining between 18 and 37 km above sea level. In 2013, a balloon named BS 13-08 reached a record altitude of 53.7 km.
A gas balloon is a balloon that rises and floats in the air because it is filled with a gas lighter than air. When not in flight, it is tethered to prevent it from flying away and is sealed at the bottom to prevent the escape of gas. A gas balloon may also be called a Charlière for its inventor, the Frenchman Jacques Charles. Today, familiar gas balloons include large blimps and small latex party balloons. For nearly 200 years, well into the 20th century, manned balloon flight utilized gas balloons before hot-air balloons became dominant. Without power, heat or fuel, untethered flights of gas balloons depended on the skill of the pilot. Gas balloons have greater lift for a given volume, so they do not need to be so large, and they can stay up for much longer than hot air balloons.
The Columbia Scientific Balloon Facility (CSBF), established in 1961 and formerly known as the National Scientific Balloon Facility (NSBF), is a NASA facility responsible for providing launch, tracking and control, airspace coordination, telemetry and command systems, and recovery services for unmanned high-altitude balloons. Customers of the CSBF include NASA centers, universities, and scientific groups from all over the world.
A solar balloon is a balloon that gains buoyancy when the air inside is heated by solar radiation, usually with the help of black or dark balloon material. The heated air inside the solar balloon expands and has lower density than the surrounding air. As such, a solar balloon is similar to a hot air balloon. Usage of solar balloons is predominantly in the toy market, although it has been proposed that they be used in the investigation of planet Mars, and some solar balloons are large enough for human flight. A vent at the top can be opened to release hot air for descent and deflation.
The colonization of Venus has been a subject of many works of science fiction since before the dawn of spaceflight, and is still discussed from both a fictional and a scientific standpoint. However, with the discovery of Venus's extremely hostile surface environment, attention has largely shifted towards the colonization of the Moon and Mars instead, with proposals for Venus focused on habitats floating in the upper-middle atmosphere and on terraforming.
In meteorology, convective instability or stability of an air mass refers to its ability to resist vertical motion. A stable atmosphere makes vertical movement difficult, and small vertical disturbances dampen out and disappear. In an unstable atmosphere, vertical air movements tend to become larger, resulting in turbulent airflow and convective activity. Instability can lead to significant turbulence, extensive vertical clouds, and severe weather such as thunderstorms.
A reference atmospheric model describes how the ideal gas properties of an atmosphere change, primarily as a function of altitude, and sometimes also as a function of latitude, day of year, etc. A static atmospheric model has a more limited domain, excluding time. A standard atmosphere is defined by the World Meteorological Organization as "a hypothetical vertical distribution of atmospheric temperature, pressure and density which, by international agreement, is roughly representative of year-round, midlatitude conditions."
Julian Nott was a British balloonist who later lived in Santa Barbara, California. He was known for his record-setting achievements. Nott set 79 world ballooning records and 96 British aviation records. He developed balloons for flights to Solar System destinations, particularly Titan. He flew a working prototype Titan balloon at minus 175 Celsius, approximately the temperature of Titan's atmosphere.
The Global horizontal sounding technique (GHOST) program was an atmospheric field research project in the late 1960s for investigating the technical ability to gather weather data using hundreds of simultaneous long-duration balloons for very long-range global scale numerical weather prediction in preparation for the Global Atmospheric Research Program (GARP).
A sky anchor is a system of two balloons in tandem, with a "zero-pressure" lifting gas balloon tethered to a superpressure balloon "anchor". The gas balloon is filled with a lifting gas and provides the buoyancy, while the superpressure balloon is filled with air, and pressurized to provide the desired ballast weight. In a passive sky anchor, the superpressure balloon is sealed, while in an active system, its pressure can be varied. Both versions have been tested in flight, but have had frequent failures with only occasional successful outcomes. The tandem arrangement makes launching difficult, and this complexity can lead to mission failure.
A lifting gas or lighter-than-air gas is a gas that has a density lower than normal atmospheric gases and rises above them as a result. It is required for aerostats to create buoyancy, particularly in lighter-than-air aircraft, which include free balloons, moored balloons, and airships. Only certain lighter than air gases are suitable as lifting gases. Dry air has a density of about 1.29 g/L at standard conditions for temperature and pressure (STP) and an average molecular mass of 28.97 g/mol, and so lighter-than-air gases have a density lower than this.
Light Heart was a balloon constructed by Colonel Thomas Leigh Gatch Jr., USAR for an unsuccessful attempt at the first crossing of the Atlantic Ocean by balloon.
The GUSTO mission is a high-altitude balloon mission that carry an infrared telescope to measure fine-structure line emission from the interstellar medium. The mission was developed by NASA's Explorers Program, and was launched in December 2023 from Antarctica.
The Super-pressure Balloon-borne Imaging Telescope (SuperBIT) is a highly stabilized, high-resolution telescope that operates in the stratosphere via NASA's superpressure balloon (SPB) system. At 40 km altitude above sea level, the football-stadium-sized balloon carries SuperBIT to a suborbital environment above 99.2% of the Earth's atmosphere in order to obtain space-quality imaging. As a research instrument, SuperBIT's primary science goal is to provide insight into the distribution of dark matter in galaxy clusters and throughout the large-scale structure of the universe. As demonstrated by numerous test flights, the survey data generated by SuperBIT is expected to have similar quality and data collection efficiency as the Hubble Space Telescope while complementing surveys from other up-and-coming observatories such as the James Webb Space Telescope (JWST), the Vera C. Rubin Observatory, and the Nancy Grace Roman Space Telescope.
