A superpressure balloon (SPB) is a style of aerostatic

balloon A balloon is a flexible bag that can be inflated with a gas, such as helium, hydrogen, nitrous oxide, oxygen, and air. For special tasks, balloons can be filled with smoke, liquid water, granular media (e.g. sand, flour or rice), or light so ...

where the volume of the balloon is kept relatively constant in the face of changes in ambient pressure outside the balloon, and the temperature of the contained

lifting gas 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 ballo ...

. This allows the balloon to keep a stable altitude for long periods. This is in contrast with much more common variable-volume balloons, which are either only partially filled with lifting gas, or made with more elastic materials. Also referred to as pumpkin or Ultra Long Distance Balloons (ULDB) balloons, the sealed balloon envelopes have a pumpkin shape at flight altitude.

Operation

In a variable-volume balloon, the

volume Volume is a measure of occupied three-dimensional space. It is often quantified numerically using SI derived units (such as the cubic metre and litre) or by various imperial or US customary units (such as the gallon, quart, cubic inch). Th ...

of the lifting gas changes due to heating and cooling in the diurnal cycle. The cycle is magnified by a

greenhouse effect The greenhouse effect is a process that occurs when energy from a planet's host star goes through the planet's atmosphere and heats the planet's surface, but greenhouse gases in the atmosphere prevent some of the heat from returning directly ...

inside the balloon, while the surrounding atmospheric gas is subject to a much more limited cyclical temperature change. As the lift gas heats and expands, the

displacement Displacement may refer to: Physical sciences Mathematics and Physics * Displacement (geometry), is the difference between the final and initial position of a point trajectory (for instance, the center of mass of a moving object). The actual path ...

of atmospheric gas increases, while the balloon weight remains constant. Its

buoyancy 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 ...

increases, and this leads to a rise in

altitude Altitude or height (also sometimes known as depth) is a distance measurement, usually in the vertical or "up" direction, between a reference datum and a point or object. The exact definition and reference datum varies according to the context ...

unless it is compensated by venting gas. Conversely, if the balloon cools and drops, it becomes necessary to release

ballast Ballast is material that is used to provide stability to a vehicle or structure. Ballast, other than cargo, may be placed in a vehicle, often a ship or the gondola of a balloon or airship, to provide stability. A compartment within a boat, ship ...

. Since both ballast and gas are finite, there is a limit to how long a variable-volume balloon can compensate in order to stabilize its altitude. In contrast, a superpressure balloon experiences smaller changes in altitude without compensation maneuvers. Because the volume of the balloon is more constrained, so is the volume of air displaced by it. In accordance with the Principle of Archimedes, the upward

force In physics, a force is an influence that can change the motion of an object. A force can cause an object with mass to change its velocity (e.g. moving from a state of rest), i.e., to accelerate. Force can also be described intuitively as a p ...

on the balloon is equal to the

weight In science and engineering, the weight of an object is the force acting on the object due to gravity. Some standard textbooks define weight as a vector quantity, the gravitational force acting on the object. Others define weight as a scalar qua ...

of the displaced ambient gas. In this case the ambient gas is the atmospheric gas displaced by the balloon. The

of the displaced atmospheric gas decreases as the balloon rises, because atmospheric density diminishes with increasing altitude. So the force pushing the balloon upward diminishes with altitude and at some particular altitude, the upward force equals the weight of the balloon. As a result, the balloon remains stable in a finite equilibrium altitude range for long periods. The disadvantage is that such balloons require much stronger materials than non-pressurized types.

Applications

Superpressure balloons (SPB) are typically used for extremely long duration flights of unmanned

scientific experiment An experiment is a procedure carried out to support or refute a hypothesis, or determine the efficacy or likelihood of something previously untried. Experiments provide insight into cause-and-effect by demonstrating what outcome occurs when a ...

s in the

upper atmosphere Upper atmosphere is a collective term that refers to various layers of the atmosphere of the Earth above the troposphere and corresponding regions of the atmospheres of other planets, and includes: * The mesosphere, which on Earth lies between th ...

, where atmospheric gas temperature is quite stable through the diurnal cycle. In 1985, such balloons were used for

aerobot An aerobot is an aerial robot, usually used in the context of an unmanned space probe or unmanned aerial vehicle. While work has been done since the 1960s on robot "rovers" to explore the Moon and other worlds in the Solar System, such machines h ...

s flying at an altitude of approximately in the atmosphere of

Venus Venus is the second planet from the Sun. It is sometimes called Earth's "sister" or "twin" planet as it is almost as large and has a similar composition. As an interior planet to Earth, Venus (like Mercury) appears in Earth's sky never fa ...

, in the international, Soviet-led

Vega program The Vega program (Cyrillic: ВеГа) was a series of Venus missions that also took advantage of the appearance of comet 1P/Halley in 1986. ''Vega 1'' and '' Vega 2'' were uncrewed spacecraft launched in a cooperative effort among the Soviet ...

. In February 1974, Colonel Thomas L. Gatch Jr, USAR attempted to make the first crossing of the

Atlantic The Atlantic Ocean is the second-largest of the world's five oceans, with an area of about . It covers approximately 20% of Earth's surface and about 29% of its water surface area. It is known to separate the " Old World" of Africa, Europe an ...

by balloon in a superpressure balloon named '' Light Heart''. Following the loss of at least two of the ten balloons which provided lift, and after deviating substantially from the course that Colonel Gatch had plotted to take advantage of the

jet stream Jet streams are fast flowing, narrow, meandering thermal wind, air currents in the Atmosphere of Earth, atmospheres of some planets, including Earth. On Earth, the main jet streams are located near the altitude of the tropopause and are west ...

, the last reported sighting of the ''Light Heart'' was west of the

Canary Islands The Canary Islands (; es, Canarias, ), also known informally as the Canaries, are a Spanish autonomous community and archipelago in the Atlantic Ocean, in Macaronesia. At their closest point to the African mainland, they are west of Morocc ...

; no further trace of the aircraft was ever found. In March 2015,

NASA The National Aeronautics and Space Administration (NASA ) is an independent agency of the US federal government responsible for the civil space program, aeronautics research, and space research. NASA was established in 1958, succeeding t ...

launched a SPB to an altitude of for 32 days from New Zealand and landed it in Australia after a leak was detected. This was the first time a SPB was flown for a long duration through the day and night cycle. When fully inflated, it was the size of a football stadium. Google's

Project Loon Loon LLC was an Alphabet Inc. subsidiary working on providing Internet access to rural and remote areas. The company used high-altitude balloons in the stratosphere at an altitude of to to create an aerial wireless network with up to 1 Mbi ...

uses controllable altitude superpressure balloons to achieve flights of over 300 days. The SPB TRAVALB-2 surpassed previous Antarctic balloon flights by staying aloft for 149 Days, 3 hours, and 58 minutes after launch from the

Long Duration Balloon (LDB) site at LDB Camp, McMurdo Station, Antarctica. The operation was supported by

National Science Foundation The National Science Foundation (NSF) is an independent agency of the United States government that supports fundamental research and education in all the non-medical fields of science and engineering. Its medical counterpart is the National ...

and

United States Antarctic Program The United States Antarctic Program (or USAP; formerly known as the United States Antarctic Research Program or USARP and the United States Antarctic Service or USAS) is an organization of the United States government which has presence in the A ...

. After the Travalb-1 launch abort, the Travalb-2 lifted off on 29 December 2019 to test NASA balloon trajectory predictions in Antarctica and to study electron losses from Earth's radiation belts. The Super-pressure Balloon-borne Imaging Telescope (SuperBIT) is staged for a 30+ day flight from on NASA's SPB system in March 2022. Launched from

Wānaka Wānaka () is a popular ski and summer resort town in the Otago region of the South Island of New Zealand. At the southern end of Lake Wānaka, it is at the start of the Clutha River/Mata-Au and is the gateway to Mount Aspiring National Park. ...

, New Zealand, SuperBIT intends to take advantage of day and night cycles made possible by SPB in order to obtain space-quality,

diffraction-limited The resolution of an optical imaging system a microscope, telescope, or camera can be limited by factors such as imperfections in the lenses or misalignment. However, there is a principal limit to the resolution of any optical system, due to t ...

imaging from the stratosphere.

References

External links

NASA Superpressure balloon
showing a superpressure balloon over Antarctica.
Nott's Super-pressure balloon
{{DEFAULTSORT:Superpressure Balloon Balloons (aeronautics)

Operation

Applications

See also

References

External links