 SES-14 with GOLD (bottom left of satellite) | |
| Names | GOLD |
|---|---|
| Mission type | Observation of Earth'sthermosphere andionosphere |
| Operator | Laboratory for Atmospheric and Space Physics |
| COSPAR ID | 2018-012B |
| SATCATno. | 43175 |
| Website | gold |
| Mission duration | 2 years (planned)[1] |
| Spacecraft properties | |
| Spacecraft type | Explorer |
| Manufacturer | Laboratory for Atmospheric and Space Physics |
| Launch mass | 36.8 kg (81 lb)[2] |
| Dimensions | 51 cm × 55 cm × 69 cm (20 in × 22 in × 27 in)[2] |
| Power | 72.4 watts[2] |
| Start of mission | |
| Launch date | 25 January 2018, 22:20UTC[3] |
| Rocket | Ariane 5 ECA,VA241 |
| Launch site | Centre Spatial Guyanais,Kourou,ELA-3 |
| Contractor | Arianespace |
| Entered service | October 2018 |
| Orbital parameters | |
| Reference system | Geocentric orbit (planned)[4] |
| Regime | Geostationary orbit |
| MainImaging spectrograph | |
| Wavelengths | Far ultraviolet[5] |
| Transponders | |
| Bandwidth | 6 Mbps[2] |
Global-scale Observations of the Limb and Disk (GOLD) is aheliophysics Mission of Opportunity (MOU) forNASA'sExplorers program.[6] Led by Richard Eastes at theLaboratory for Atmospheric and Space Physics, which is located at theUniversity of Colorado Boulder,GOLD's mission is to image the boundary betweenEarth and space in order to answer questions about the effects of solar and atmospheric variability of Earth'sspace weather.[7]GOLD was one of 11 proposals selected, of the 42 submitted, for further study in September 2011.[8] On 12 April 2013, NASA announced thatGOLD, along with theIonospheric Connection Explorer (ICON), had been selected for flight in 2017.[6] GOLD, along with its commercial host satelliteSES-14, launched on 25 January 2018.[9]
GOLD is intended to perform a two-year mission imaging Earth'sthermosphere andionosphere fromgeostationary orbit.GOLD is a two-channelfar-ultraviolet (FUV) imagingspectrograph built by theLaboratory for Atmospheric and Space Physics at theUniversity of Colorado Boulder and flown as a hosted payload on the commercial communications satelliteSES-14.[10] Additional organizations participating in theGOLD mission include theNational Center for Atmospheric Research,Virginia Tech, theUniversity of California, Berkeley, theUniversity of Central Florida, Computational Physics Inc., theNational Oceanic and Atmospheric Administration (NOAA), theU.S. Naval Research Laboratory (NRL),Boston University, andClemson University.
In June 2017,SES announced the successful integration ofGOLD with the SES-14 satellite under construction atAirbus Defence and Space inToulouse,France.[11]GOLD was launched on 25 January 2018 at 22:20UTC aboardAriane 5 ECAVA241 from theCentre spatial Guyanais.[9]
The scientific objectives of theGOLD 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 ofatmospheric waves 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 byGOLD's 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.[7]
Data fromGOLD has been used to confirm that variation in theequatorial ionization anomaly at night and in the early morning is governed by atmospheric waves in the lower atmosphere.GOLD observations have also implicatedgravity waves emanating from the lower atmosphere in the seeding ofequatorial plasma bubbles, which degradeGPS performance.[12]GOLD daytime observations of the thermosphere column density ratio of atomic oxygen and nitrogen revealed new findings. First, GOLD observations showed that even weak or minor geomagnetic activity (maximum Kp=1.7) can still generate significant disturbances in the thermosphere and ionosphere. This is crucial for space weather forecasting because the pre-quiet condition before the disturbed time determines the accuracy of the forecast. Second, the neutral tongue, which is an enhancement of O/N2 surrounded by depletion of O/N2 and had only been seen in simulations, was first observed by GOLD. This modified the classic theory of thermospheric composition disturbance during storms. The theory predicted that the disturbance co-rotates from day to night but did not specify what else happens to the depletion.
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