The Stratospheric Aerosol and Gas Experiment (SAGE) is a series of

remote sensing Remote sensing is the acquisition of information about an object or phenomenon without making physical contact with the object, in contrast to in situ or on-site observation. The term is applied especially to acquiring information about Ear ...

satellite instruments used to study the chemical composition of

Earth's atmosphere 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 protects life on Earth by creating pressure allowing fo ...

. Specifically, SAGE has been used to study the Earth's

ozone layer The ozone layer or ozone shield is a region of Earth's stratosphere that absorbs most of the Sun's ultraviolet radiation. It contains a high concentration of ozone (O3) in relation to other parts of the atmosphere, although still small in rel ...

and

aerosols An aerosol is a suspension of fine solid particles or liquid droplets in air or another gas. Aerosols can be natural or anthropogenic. Examples of natural aerosols are fog or mist, dust, forest exudates, and geyser steam. Examples of a ...

at the

troposphere The troposphere is the first and lowest layer of the atmosphere of the Earth, and contains 75% of the total mass of the planetary atmosphere, 99% of the total mass of water vapour and aerosols, and is where most weather phenomena occur. Fro ...

through the

stratosphere The stratosphere () is the second layer of the atmosphere of the Earth, located above the troposphere and below the mesosphere. The stratosphere is an atmospheric layer composed of stratified temperature layers, with the warm layers of air h ...

. The SAGE instruments use solar occultation measurement technique to determine chemical concentrations in the atmosphere. Solar occultation measurement technique measures sunlight through the atmosphere and ratios that measurement with a sunlight measurement without

atmospheric An atmosphere () is a layer of gas or layers of gases that envelop a planet, and is held in place by the gravity of the planetary body. A planet retains an atmosphere when the gravity is great and the temperature of the atmosphere is low. A ...

attenuation In physics, attenuation (in some contexts, extinction) is the gradual loss of flux intensity through a medium. For instance, dark glasses attenuate sunlight, lead attenuates X-rays, and water and air attenuate both light and sound at var ...

. This is achieved by observing sunrises and sunsets during a satellite orbit. Physically, the SAGE instruments measure ultraviolet/visible energy and this is converted via

algorithms In mathematics and computer science, an algorithm () is a finite sequence of rigorous instructions, typically used to solve a class of specific problems or to perform a computation. Algorithms are used as specifications for performing ...

to determine chemical

concentrations In chemistry, concentration is the abundance of a constituent divided by the total volume of a mixture. Several types of mathematical description can be distinguished: '' mass concentration'', ''molar concentration'', ''number concentration'', a ...

. SAGE data has been used to study the atmospheres aerosols, ozone, water vapor, and other trace gases.

History

There has been 4 series of SAGE instruments: * SAGE I - Flew on the

Explorer 60 Explorer 60, also called as SAGE (Stratospheric Aerosol and Gas Experiment) and was the second of the Applications Explorer Missions (AEM), AEM-B (Applications Explorer Mission-B), was a NASA scientific satellite launched on 18 February 1979, f ...

satellite. * SAGE II - Flew on the

Earth Radiation Budget Satellite The Earth Radiation Budget Satellite (ERBS) is a NASA scientific research satellite within NASA's ERBE (Earth Radiation Budget Experiment) Research Program - a three-satellite mission, designed to investigate the Earth radiation budget. It al ...

(ERBS). * SAGE III - Flew on the Meteor-3M No.1. *

SAGE III on ISS SAGE III on ISS is the fourth generation of a series of NASA Earth-observing instruments, known as the Stratospheric Aerosol and Gas Experiment. The first SAGE III instrument was launched on a Russian Meteor-3M satellite. The recently revis ...

, was launched on the

SpaceX CRS-10 SpaceX CRS-10, also known as SpX-10, was a Dragon Commercial Resupply Service mission to the International Space Station (ISS) which launched on 19 February 2017. The mission was contracted by NASA as part of its Commercial Resupply Services pr ...

mission using a

Falcon 9 Falcon 9 is a partially reusable medium lift launch vehicle that can carry cargo and crew into Earth orbit, produced by American aerospace company SpaceX. The rocket has two stages. The first (booster) stage carries the second stage and pay ...

with Cargo Dragon. It was launched on 19 February 2017 and installed on the

International Space Station The International Space Station (ISS) is the largest Modular design, modular space station currently in low Earth orbit. It is a multinational collaborative project involving five participating space agencies: NASA (United States), Roscosmos ( ...

(ISS).

References

External links

SAGE on ISS
Satellite meteorology Aerosol measurement {{US-spacecraft-stub