UPDATE: Following an "anomaly" that caused a communications dropout after ignition of the upper stage, Arianespace has reported that both satellites aboard the rocket "were confirmed separated, acquired and they are on orbit."

NASA's Global-Scale Observations of the Limb and Disk (GOLD) instrument was launched earlier today atop an Ariane 5 rocket, with a mission to shed light on how the uppermost layers of Earth's atmosphere can be affected by powerful space and Earth-based weather events.

Earth's atmosphere is a complex, multi-layered protective shell that envelopes our planet, and safeguards its inhabitants from dangerous space weather emanating largely from our Sun.

Once operational, GOLD will focus its attention on a relatively poorly-understood region of the upper atmosphere, where the charged particles of the ionosphere mingle with the diffuse neutral gasses that make up the thermosphere.

This tenuous region of the atmosphere has been known to undergo swift and significant changes in less than an hour. These fluctuations can be driven by the constant interactions between the ionosphere and thermosphere, in conjunction with weather emanating from both Earth and space. For example, powerful weather events such as tsunamis and tornadoes can lead to shifts in wind patterns that translate to, and disrupt, the upper atmosphere. From the heavens, gigantic solar storms can send vast clouds of energized particles and magnetic fields crashing into the atmosphere where it wreaks havock with the Earth/space interface.

The complexity of these interactions makes it very difficult to predict when an atmospheric change in the ionosphere and thermosphere will occur, and this can be a serious problem for satellite communications. Disturbances in the ionosphere can interfere with, or even block signals being sent between Earth-based systems and orbital probes, potentially affecting cell-phone communications, and other vital services such as GPS, which is needed to safely navigate airplanes and ships.

"The upper atmosphere is far more variable than previously imagined, but we don't understand the interactions between all the factors involved," said Richard Eastes, GOLD principal investigator at the Laboratory for Atmospheric and Space Physics at the University of Colorado Boulder. "That's where GOLD comes in: For the first time, the mission gives us the big picture of how different drivers meet and influence each other."

GOLD is essentially an imaging spectrograph. Spectrographs are scientific instruments that have been designed to break light down into its constituent wavelengths and to measure their intensity. By examining the data from such an instrument, scientists can determine a wide variety of characteristics, including a target's composition and temperature. GOLD will be tasked with collecting far ultraviolet light data on Earth's atmosphere.

The mission will operate from a distance of 22,000 miles (35,406 km) above the Earth in a geostationary orbit, which means that the spacecraft will essentially remain stationary relative to our planet's surface. This high vantage point will allow GOLD to scan Earth's full disk once every half hour, creating a global ultraviolet map of the atmosphere displaying variations in temperature and in the type and distribution of particles at the "edge" of space.

In a historic first for a NASA science mission, GOLD headed into orbit hosted by one of the primary payloads for today's launch – the Airbus-built commercial communications satellite SES-14. The commercial satellite has nothing to do with the NASA mission observing Earth's atmosphere, and was chosen to host GOLD in part due to the endeavours' shared orbital requirements. With the 36-kg (80-lb) GOLD instrument secured onboard, SES-14 will have a launch weight of 4,400 kg (9,700 lb). SES-14 is expected to remain operational in space for over 15 years.

GOLD is due to operate in concert with a second NASA mission – the Ionospheric Connection Explorer (ICON). ICON will be tasked with observing the upper atmosphere from low-Earth orbit in greater detail, but on a smaller scale, at a distance of only 350 miles (563 km)above the Earth, about 100 miles (160 km) above the International Space Station.

ICON was slated to launch on November 3, last year, but it was decided that both NASA and Orbital ATK, the supplier of the launch vehicle that would carry the probe to orbit, needed more time to assess a stage separator. No revised launch date has been announced at the time of writing.

Once in orbit, GOLD and ICON will provide comprehensive frequent data on the drivers for atmospheric change in the upper atmosphere, and through access to these datasets, scientists may be able to better predict changes occurring at the outermost regions of the thin blue line.

Source: NASA