Global-scale Observations of the Limb and Disk (GOLD) is a
heliophysics
Heliophysics (from the prefix " helio", from Attic Greek ''hḗlios'', meaning Sun, and the noun "physics": the science of matter and energy and their interactions) is the physics of the Sun and its connection with the Solar System. NASA define ...
Mission of Opportunity (MOU) for
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 ...
's
Explorers program
The Explorers program is a NASA exploration program that provides flight opportunities for physics, geophysics, heliophysics, and astrophysics investigations from space. Launched in 1958, Explorer 1 was the first spacecraft of the United Stat ...
.
[ ] Led by Richard Eastes at the
Laboratory for Atmospheric and Space Physics
The Laboratory for Atmospheric and Space Physics (LASP) is a research organization at the University of Colorado Boulder. LASP is a research institute with over one hundred research scientists ranging in fields from solar influences, to Earth' ...
, which is located at the
University of Colorado Boulder
The University of Colorado Boulder (CU Boulder, CU, or Colorado) is a public research university in Boulder, Colorado. Founded in 1876, five months before Colorado became a state, it is the flagship university of the University of Colorado syst ...
, ''GOLD'' mission is to image the boundary between
Earth
Earth is the third planet from the Sun and the only astronomical object known to harbor life. While large volumes of water can be found throughout the Solar System, only Earth sustains liquid surface water. About 71% of Earth's surfa ...
and space in order to answer questions about the effects of solar and atmospheric variability of Earth's
space weather
Space weather is a branch of space physics and aeronomy, or heliophysics, concerned with the time varying conditions within the Solar System, including the solar wind, emphasizing the space surrounding the Earth, including conditions in the ma ...
.
''GOLD'' was one of 11 proposals selected, of the 42 submitted, for further study in September 2011.
[ ] On 12 April 2013, NASA announced that ''GOLD'', along with the
Ionospheric Connection Explorer
Ionospheric Connection Explorer (ICON) is a satellite designed to investigate changes in the ionosphere of Earth, the dynamic region high in our atmosphere where terrestrial weather from below meets space weather from above. ICON studies the i ...
(''ICON''), had been selected for flight in 2017.
GOLD, along with its commercial host satellite
SES-14
SES-14 is a geostationary communications satellite operated by SES S.A. at 47.5° West, replaces NSS-806, and designed and manufactured by Airbus Defence and Space. The satellite launched on 25 January 2018 at 22:20 UTC along with the Global ...
, launched on 25 January 2018.
[
]
Mission concept and history
''GOLD'' is intended to perform a two-year mission imaging Earth's thermosphere
The thermosphere is the layer in the Earth's atmosphere directly above the mesosphere and below the exosphere. Within this layer of the atmosphere, ultraviolet radiation causes photoionization/photodissociation of molecules, creating ions; the ...
and ionosphere
The ionosphere () is the ionized part of the upper atmosphere of Earth, from about to above sea level, a region that includes the thermosphere and parts of the mesosphere and exosphere. The ionosphere is ionized by solar radiation. It plays an ...
from geostationary orbit
A geostationary orbit, also referred to as a geosynchronous equatorial orbit''Geostationary orbit'' and ''Geosynchronous (equatorial) orbit'' are used somewhat interchangeably in sources. (GEO), is a circular geosynchronous orbit in altitud ...
. ''GOLD'' is a two-channel far-ultraviolet
Ultraviolet (UV) is a form of electromagnetic radiation with wavelength from 10 nanometer, nm (with a corresponding frequency around 30 Hertz, PHz) to 400 nm (750 Hertz, THz), shorter than that of visible light, but longer than ...
(FUV) imaging spectrograph
An optical spectrometer (spectrophotometer, spectrograph or spectroscope) is an instrument used to measure properties of light over a specific portion of the electromagnetic spectrum, typically used in spectroscopic analysis to identify mate ...
built by the Laboratory for Atmospheric and Space Physics
The Laboratory for Atmospheric and Space Physics (LASP) is a research organization at the University of Colorado Boulder. LASP is a research institute with over one hundred research scientists ranging in fields from solar influences, to Earth' ...
at the University of Colorado Boulder
The University of Colorado Boulder (CU Boulder, CU, or Colorado) is a public research university in Boulder, Colorado. Founded in 1876, five months before Colorado became a state, it is the flagship university of the University of Colorado syst ...
and flown as a hosted payload on the commercial communications satellite SES-14
SES-14 is a geostationary communications satellite operated by SES S.A. at 47.5° West, replaces NSS-806, and designed and manufactured by Airbus Defence and Space. The satellite launched on 25 January 2018 at 22:20 UTC along with the Global ...
. Additional organizations participating in the ''GOLD'' mission include the National Center for Atmospheric Research
The US National Center for Atmospheric Research (NCAR ) is a US federally funded research and development center (FFRDC) managed by the nonprofit University Corporation for Atmospheric Research (UCAR) and funded by the National Science Foundatio ...
, Virginia Tech
Virginia Tech (formally the Virginia Polytechnic Institute and State University and informally VT, or VPI) is a Public university, public Land-grant college, land-grant research university with its main campus in Blacksburg, Virginia. It also ...
, the University of California, Berkeley
The University of California, Berkeley (UC Berkeley, Berkeley, Cal, or California) is a public land-grant research university in Berkeley, California. Established in 1868 as the University of California, it is the state's first land-grant u ...
, the University of Central Florida
The University of Central Florida (UCF) is a public research university whose main campus is in unincorporated Orange County, Florida. UCF also has nine smaller regional campuses throughout central Florida. It is part of the State University ...
, Computational Physics Inc., the National Oceanic and Atmospheric Administration
The National Oceanic and Atmospheric Administration (abbreviated as NOAA ) is an United States scientific and regulatory agency within the United States Department of Commerce that forecasts weather, monitors oceanic and atmospheric conditio ...
(NOAA), the U.S. Naval Research Laboratory
The United States Naval Research Laboratory (NRL) is the corporate research laboratory for the United States Navy and the United States Marine Corps. It was founded in 1923 and conducts basic scientific research, applied research, technological ...
(NRL), Boston University
Boston University (BU) is a private research university in Boston, Massachusetts. The university is nonsectarian, but has a historical affiliation with the United Methodist Church. It was founded in 1839 by Methodists with its original campu ...
, and Clemson University
Clemson University () is a public land-grant research university in Clemson, South Carolina. Founded in 1889, Clemson is the second-largest university in the student population in South Carolina. For the fall 2019 semester, the university enro ...
.
In June 2017, SES
SES, S.E.S., Ses and similar variants can refere to:
Business and economics
* Socioeconomic status
* Scottish Economic Society, a learned society in Scotland
* SES, callsign of the TV station SES/RTS (Mount Gambier, South Australia)
* SES S.A., ...
announced the successful integration of ''GOLD'' with the SES-14 satellite under construction at Airbus Defence and Space
Airbus Defence and Space is the division of Airbus SE responsible for the development and manufacturing of the corporation's defence and space products, while also providing related services. The division was formed in January 2014 during the ...
in Toulouse
Toulouse ( , ; oc, Tolosa ) is the prefecture of the French department of Haute-Garonne and of the larger region of Occitania. The city is on the banks of the River Garonne, from the Mediterranean Sea, from the Atlantic Ocean and from Par ...
, France
France (), officially the French Republic ( ), is a country primarily located in Western Europe. It also comprises of Overseas France, overseas regions and territories in the Americas and the Atlantic Ocean, Atlantic, Pacific Ocean, Pac ...
. ''GOLD'' was launched on 25 January 2018 at 22:20 UTC aboard Ariane 5 ECA VA241 from the Centre spatial Guyanais.
Scientific objectives
The scientific objectives of the ''GOLD'' mission are to determine how geomagnetic storms alter the temperature and composition of Earth's atmosphere, to analyze the global-scale response of the thermosphere to solar extreme-ultraviolet variability, to investigate the significance of atmospheric waves
An atmospheric wave is a periodic disturbance in the fields of atmospheric variables (like surface pressure or geopotential height, temperature, or wind velocity) which may either propagate (''traveling wave'') or not ('' standing wave''). Atmo ...
and tides propagating from below the temperature structure of the thermosphere and to resolve how the structure of the equatorial ionosphere influences the formation and evolution of equatorial plasma density irregularities. The viewpoint provided by ''GOLD'' geostationary orbit from which the same hemisphere is always observable is a new perspective on the Earth's upper atmosphere. This viewpoint allows local time, universal time and longitudinal variations of the thermosphere and ionosphere's response to the various forcing mechanisms to be uniquely determined.[
]
Results
Data from ''GOLD'' has been used to confirm that variation in the equatorial ionization anomaly at night and in the early morning is governed by atmospheric waves in the lower atmosphere. ''GOLD'' observations have also implicated gravity wave
In fluid dynamics, gravity waves are waves generated in a fluid medium or at the interface between two media when the force of gravity or buoyancy tries to restore equilibrium. An example of such an interface is that between the atmosphere ...
s emanating from the lower atmosphere in the seeding of equatorial plasma bubble Equatorial plasma bubbles are an ionospheric phenomenon near the Earth's geomagnetic equator at night time. They affect radio waves by causing varying delays. They degrade the performance of GPS.
Different times of the year and locations have diffe ...
s, which degrade GPS
The Global Positioning System (GPS), originally Navstar GPS, is a Radionavigation-satellite service, satellite-based radionavigation system owned by the United States government and operated by the United States Space Force. It is one of t ...
performance.[ ]
GOLD daytime observations on thermosphere column density ratio of atomix oxygen and Nitregon bring a lot of new findings. First, GOLD observation shows that even weak, or minor geomagnetic activity (maximum Kp=1.7) can still generate significant disturbance in the thermosphere and ionosphere. This is crucial for the space weather forecast because the pre-quiet condition before the disturbed time determines the accuracy of forecast. Furthermore, the neutral tongue, which is an enhancement of O/N2 surrounded by depletion of O/N2, and had only been discovered in model simulations, is observed firstly by GOLD.This modify the classic theory of thermospheric composition disturbance during storm time. The theory only predict that the disturbance corotate from day to night, but did not mention what else occur to the depletion.
References
External links
GOLD website
by the University of Central Florida
The University of Central Florida (UCF) is a public research university whose main campus is in unincorporated Orange County, Florida. UCF also has nine smaller regional campuses throughout central Florida. It is part of the State University ...
GOLD website
by NASA
{{Explorers program
Spacecraft instruments
Explorers Program
Spacecraft launched in 2018
Piggyback mission
Spectrometers
Geospace monitoring satellites