A-train (satellite constellation)

Last updated
A-train in 2013. As of 2020, the A-Train consists of four satellites. CloudSat and CALIPSO are no longer officially part of the constellation. A-Train w-Time2013 Web.jpg
A-train in 2013. As of 2020, the A-Train consists of four satellites. CloudSat and CALIPSO are no longer officially part of the constellation.

The A-train (from Afternoon Train) is a satellite constellation of four Earth observation satellites of varied nationality in Sun-synchronous orbit at an altitude that is slightly variable for each satellite. [1]

Contents

The orbit, at an inclination of 98.14°, crosses the equator each day at around 1:30 pm solar time, giving the constellation its name (the "A" stands for "afternoon" [2] ) and crosses the equator again on the night side of the Earth, at around 1:30 am.

They are spaced a few minutes apart from each other so their collective observations may be used to build high-definition three-dimensional images of Earth's atmosphere and surface.

Satellites

Active

A-train and C-train in 2019 A-Train and C-Train constellations - 2019-09.jpg
A-train and C-train in 2019

The train, as of January 2022, [3] [4] [5] consists of three active satellites:

Past

Failed

Related Research Articles

<span class="mw-page-title-main">CNES</span> French space agency

The National Centre for Space Studies is the French national space agency headquartered in central Paris and it comes under the supervision of the French Ministries of Defence and Research.

<span class="mw-page-title-main">Terra (satellite)</span> NASA climate research satellite

Terra is a multi-national, NASA scientific research satellite in a Sun-synchronous orbit around the Earth that takes simultaneous measurements of Earth's atmosphere, land, and water to understand how Earth is changing and to identify the consequences for life on Earth. It is the flagship of the Earth Observing System (EOS) and the first satellite of the system which was followed by Aqua and Aura. Terra was launched in 1999.

<span class="mw-page-title-main">Clouds and the Earth's Radiant Energy System</span> NASA satellite climate data instruments

Clouds and the Earth's Radiant Energy System (CERES) is an on-going NASA climatological experiment from Earth orbit. The CERES are scientific satellite instruments, part of the NASA's Earth Observing System (EOS), designed to measure both solar-reflected and Earth-emitted radiation from the top of the atmosphere (TOA) to the Earth's surface. Cloud properties are determined using simultaneous measurements by other EOS instruments such as the Moderate Resolution Imaging Spectroradiometer (MODIS). Results from the CERES and other NASA missions, such as the Earth Radiation Budget Experiment (ERBE), could enable nearer to real-time tracking of Earth's energy imbalance (EEI) and better understanding of the role of clouds in global climate change.

The Earth Observing System (EOS) is a program of NASA comprising a series of artificial satellite missions and scientific instruments in Earth orbit designed for long-term global observations of the land surface, biosphere, atmosphere, and oceans. Since the early 1970s, NASA has been developing its Earth Observing System, launching a series of Landsat satellites in the decade. Some of the first included passive microwave imaging in 1972 through the Nimbus 5 satellite. Following the launch of various satellite missions, the conception of the program began in the late 1980s and expanded rapidly through the 1990s. Since the inception of the program, it has continued to develop, including; land, sea, radiation and atmosphere. Collected in a system known as EOSDIS, NASA uses this data in order to study the progression and changes in the biosphere of Earth. The main focus of this data collection surrounds climatic science. The program is the centrepiece of NASA's Earth Science Enterprise.

<span class="mw-page-title-main">Aura (satellite)</span> NASA Earth observation satellite

Aura is a multi-national NASA scientific research satellite in orbit around the Earth, studying the Earth's ozone layer, air quality and climate. It is the third major component of the Earth Observing System (EOS) following on Terra and Aqua. Aura follows on from the Upper Atmosphere Research Satellite (UARS). Aura is a joint mission between NASA, the Netherlands, Finland, and the U.K. The Aura spacecraft is healthy and is expected to operate until at least 2023, likely beyond.

<span class="mw-page-title-main">Aqua (satellite)</span> NASA scientific research satellite

Aqua is a NASA scientific research satellite in orbit around the Earth, studying the precipitation, evaporation, and cycling of water. It is the second major component of the Earth Observing System (EOS) preceded by Terra and followed by Aura.

<span class="mw-page-title-main">Advanced microwave sounding unit</span> Instrument installed on meteorological satellites

The advanced microwave sounding unit (AMSU) is a multi-channel microwave radiometer installed on meteorological satellites. The instrument examines several bands of microwave radiation from the atmosphere to perform atmospheric sounding of temperature and moisture levels.

<span class="mw-page-title-main">CALIPSO</span>

CALIPSO was a joint NASA (USA) and CNES (France) environmental satellite, built in the Cannes Mandelieu Space Center, which was launched atop a Delta II rocket on April 28, 2006. Its name stands for Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observations. CALIPSO launched alongside CloudSat.

<span class="mw-page-title-main">Parasol (satellite)</span>

PARASOL was a French-built Earth observing research satellite. It carried an instrument called POLDER which studied the radiative and microphysical properties of clouds and aerosols.

<span class="mw-page-title-main">Orbiting Carbon Observatory</span>

The Orbiting Carbon Observatory (OCO) is a NASA satellite mission intended to provide global space-based observations of atmospheric carbon dioxide. The original spacecraft was lost in a launch failure on 24 February 2009, when the payload fairing of the Taurus rocket which was carrying it failed to separate during ascent. The added mass of the fairing prevented the satellite from reaching orbit. It subsequently re-entered the atmosphere and crashed into the Indian Ocean near Antarctica. The replacement satellite, Orbiting Carbon Observatory-2, was launched 2 July 2014 aboard a Delta II rocket. The Orbiting Carbon Observatory-3, a stand-alone payload built from the spare OCO-2 flight instrument, was installed on the International Space Station's Kibō Exposed Facility in May 2019.

<span class="mw-page-title-main">Atmospheric chemistry observational databases</span> Aspect of atmospheric sciences

Over the last two centuries many environmental chemical observations have been made from a variety of ground-based, airborne, and orbital platforms and deposited in databases. Many of these databases are publicly available. All of the instruments mentioned in this article give online public access to their data. These observations are critical in developing our understanding of the Earth's atmosphere and issues such as climate change, ozone depletion and air quality. Some of the external links provide repositories of many of these datasets in one place. For example, the Cambridge Atmospheric Chemical Database, is a large database in a uniform ASCII format. Each observation is augmented with the meteorological conditions such as the temperature, potential temperature, geopotential height, and equivalent PV latitude.

<span class="mw-page-title-main">Ozone monitoring instrument</span>

The ozone monitoring instrument (OMI) is a nadir-viewing visual and ultraviolet spectrometer aboard the NASA Aura spacecraft. Aura flies in formation about 15 minutes behind Aqua, both of which orbit the Earth in a polar Sun-synchronous pattern. Aura was launched on July 15, 2004, and OMI has collected data since August 9, 2004. OMI can distinguish between aerosol types, such as smoke, dust, and sulfates, and can measure cloud pressure and coverage, which provide data to derive tropospheric ozone. OMI follows in the heritage of TOMS, SBUV, GOME, SCIAMACHY, and GOMOS. OMI measurements cover a spectral region of 264–504 nm (nanometers) with a spectral resolution between 0.42 nm and 0.63 nm and a nominal ground footprint of 13 × 24 km2 at nadir. The Aura satellite orbits at an altitude of 705 km in a sun-synchronous polar orbit with an exact 16-day repeat cycle and with a local equator crossing time of 13. 45 on the ascending node. The orbital inclination is 98.1 degrees, providing latitudinal coverage from 82° N to 82° S. It is a wide-field-imaging spectrometer with a 114° across-track viewing angle range that provides a 2600 km wide swath, enabling measurements with a daily global coverage. OMI is continuing the TOMS record for total ozone and other atmospheric parameters related to ozone chemistry and climate.

<span class="mw-page-title-main">Global Change Observation Mission</span> JAXA project of long-term observation of Earth

GCOM, is a JAXA project of long-term observation of Earth environmental changes. As a part of Japan's contributions to GEOSS, GCOM will be continued for 10 to 15 years with observation and utilization of global geophysical data such as precipitation, snow, water vapor, aerosol, for climate change prediction, water management, and food security. On May 18, 2012, the first satellite "GCOM-W" was launched. On December 23, 2017, the second satellite "GCOM-C1" was launched.

<span class="mw-page-title-main">Glory (satellite)</span> Failed NASA satellite mission

The Glory satellite was a planned NASA satellite mission that would have collected data on the chemical, micro-physical and optical properties—and the spatial and temporal distributions—of sulfate and other aerosols, and would have collected solar irradiance data for the long-term climate record. The science focus areas served by Glory included: atmospheric composition; carbon cycle, ecosystems, and biogeochemistry; climate variability and change; and water and energy cycles. The US$424 million satellite was lost on 4 March 2011, when its Taurus XL carrier rocket malfunctioned. A subsequent investigation revealed that the fairing system failed to open fully, causing the satellite to reenter the atmosphere at which point it likely broke up and burned. NASA investigators later determined the cause for the launch failure to be faulty materials provided by aluminum manufacturer Sapa Profiles.

Satellite formation flying is the coordination of multiple satellites to accomplish the objective of one larger, usually more expensive, satellite. Coordinating smaller satellites has many benefits over single satellites including simpler designs, faster build times, cheaper replacement creating higher redundancy, unprecedented high resolution, and the ability to view research targets from multiple angles or at multiple times. These qualities make them ideal for astronomy, communications, meteorology, and environmental uses.

<span class="mw-page-title-main">Orbiting Carbon Observatory 2</span> NASA climate satellite

Orbiting Carbon Observatory-2 (OCO-2) is an American environmental science satellite which launched on 2 July 2014. A NASA mission, it is a replacement for the Orbiting Carbon Observatory which was lost in a launch failure in 2009. It is the second successful high-precision CO2 observing satellite, after GOSAT.

<span class="mw-page-title-main">NOAA-20</span> NASA satellite

NOAA-20, designated JPSS-1 prior to launch, is the first of the United States National Oceanic and Atmospheric Administration's latest generation of U.S. polar-orbiting, non-geosynchronous, environmental satellites called the Joint Polar Satellite System. NOAA-20 was launched on 18 November 2017 and joined the Suomi National Polar-orbiting Partnership satellite in the same orbit. NOAA-20 operates about 50 minutes behind Suomi NPP, allowing important overlap in observational coverage. Circling the Earth from pole-to-pole, it crosses the equator about 14 times daily, providing full global coverage twice a day. This gives meteorologists information on "atmospheric temperature and moisture, clouds, sea-surface temperature, ocean color, sea ice cover, volcanic ash, and fire detection" so as to enhance weather forecasting including hurricane tracking, post-hurricane recovery by detailing storm damage and mapping of power outages.

<span class="mw-page-title-main">TROPICS (spacecraft constellation)</span> NASA mission

The Time-Resolved Observations of Precipitation structure and storm Intensity with a Constellation of Smallsats (TROPICS) mission is a NASA constellation of six small satellites, 3U CubeSats, that will measure temperature and moisture profiles and precipitation in tropical systems with unprecedented temporal frequency. This data will enable scientists to study the dynamic processes that occur in the inner core of the storm resulting in rapid genesis and intensification. William Blackwell of the Massachusetts Institute of Technology's Lincoln Laboratory in Lexington, Massachusetts is the principal investigator. The constellation was initially planned to be delivered to orbit on three launches between June and July 2022. Due to the loss of the first two satellites after a launch failure in June of 2022, the first satellites were delivered to orbit aboard a Rocket Lab Electron rocket on 7 May 2023.

References

  1. «A-train Symposium October 2007: Constellation keeps its promises», CNESMAG, January 2008
  2. NASA, Introducing the A-Train, 10.26.10 (accessed April 30 2012)
  3. Smith, Joseph M. (4 May 2022). "Aqua Turns 20".
  4. "Individual A-Train Missions". June 5, 2012. Retrieved 2013-11-15.
  5. 1 2 Greicius, Tony (2018-02-23). "CloudSat Exits the "A-Train"". NASA. Retrieved 2018-04-01.
  6. CNES News on Calipso
  7. Sister Satellites, Briefly Separated, Working Together Again
  8. "OCO homepage". Archived from the original on 2018-09-09. Retrieved 2008-02-10.
  9. Media Briefing Scheduled To Discuss Orbiting Carbon Observatory Mission
  10. Glory homepage Archived 2008-09-16 at the Wayback Machine