A superpressure balloon (SPB) is a style of

aerostat An aerostat (, via French) or lighter-than-air aircraft is an aircraft that relies on buoyancy to maintain flight. Aerostats include unpowered balloons (free-flying or tethered) and powered airships. The relative density of an aerostat as a ...

ic balloon where the volume of the

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

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, making it useful in lifting lighter-than-air aircraft. Only certain lighter-than-air gases are suitable as lift ...

. 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 regions in 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) ...

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 occurs when greenhouse gases in a planet's atmosphere insulate the planet from losing heat to space, raising its surface temperature. Surface heating can happen from an internal heat source (as in the case of Jupiter) or ...

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 the force exerted by a fluid opposing the weight of a partially or fully immersed object (which may be also be a parcel of fluid). In a column of fluid, pressure increases with depth as a result of the weight of t ...

increases, and this leads to a rise in

altitude Altitude is a distance measurement, usually in the vertical or "up" direction, between a reference datum (geodesy), datum and a point or object. The exact definition and reference datum varies according to the context (e.g., aviation, geometr ...

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

ballast Ballast is dense material used as a weight 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 ...

. 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 cause an Physical object, object to change its velocity unless counterbalanced by other forces. In mechanics, force makes ideas like 'pushing' or 'pulling' mathematically precise. Because the Magnitu ...

on the balloon is equal to the

weight In science and engineering, the weight of an object is a quantity associated with the gravitational force exerted on the object by other objects in its environment, although there is some variation and debate as to the exact definition. Some sta ...

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 ...

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 uncrewed 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 ...

s flying at an altitude of approximately in the atmosphere of

Venus Venus is the second planet from the Sun. It is often called Earth's "twin" or "sister" planet for having almost the same size and mass, and the closest orbit to Earth's. While both are rocky planets, Venus has an atmosphere much thicker ...

, in the international, Soviet-led

Vega program Vega is the brightest star in the northern constellation of Lyra. It has the Bayer designation α Lyrae, which is Latinisation of names, Latinised to Alpha Lyrae and abbreviated Alpha Lyr or α Lyr. This star is List of star systems wi ...

. 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 oceanic divisions, with an area of about . It covers approximately 17% of Earth's surface and about 24% of its water surface area. During the Age of Discovery, it was known for se ...

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 thermal wind, air currents in the Earth's Atmosphere of Earth, atmosphere. The main jet streams are located near the altitude of the tropopause and are westerly winds, flowing west to east around the gl ...

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

Canary Islands The Canary Islands (; ) or Canaries are an archipelago in the Atlantic Ocean and the southernmost Autonomous communities of Spain, Autonomous Community of Spain. They are located in the northwest of Africa, with the closest point to the cont ...

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

NASA The National Aeronautics and Space Administration (NASA ) is an independent agencies of the United States government, independent agency of the federal government of the United States, US federal government responsible for the United States ...

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 M ...

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 McMurdo Station is an American Antarctic research station on the southern tip of Ross Island. It is operated by the United States through the United States Antarctic Program (USAP), a branch of the National Science Foundation. The station is ...

, Antarctica. The operation was supported by

National Science Foundation The U.S. National Science Foundation (NSF) is an Independent agencies of the United States government#Examples of independent agencies, independent agency of the Federal government of the United States, United States federal government that su ...

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 a presence in the ...

. 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 and is the gateway to Mount Aspiring National Park. Wānaka ...

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

diffraction-limited In optics, any optical instrument or systema microscope, telescope, or camerahas a principal limit to its resolution due to the physics of diffraction. An optical instrument is said to be diffraction-limited if it has reached this limit of res ...

imaging from the stratosphere. The Chinese high-altitude balloon that was observed transiting the

United States The United States of America (USA), also known as the United States (U.S.) or America, is a country primarily located in North America. It is a federal republic of 50 U.S. state, states and a federal capital district, Washington, D.C. The 48 ...

in early 2023 was a superpressure balloon similar in style to the earlier

balloons.

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