Orbital Sciences Corporation this week secured a $56.3 million firm-fixed price launch services contract to deliver the Ionospheric Connection Explorer (ICON) mission to orbit for NASA in the summer of 2017. The mission, which is led by the University of California, Berkeley, with oversight by the Explorers Program at NASA’s Goddard Space Flight Center in Greenbelt, Md., will launch from the Reagan Test Site on Kwajalein Atoll (in the Republic of the Marshall Islands) aboard a 3-stage Pegasus XL rocket, which itself will fire over the Pacific Ocean towards a 575 km circular orbit from Orbital’s “Stargazer” L-1011 aircraft.
The mission, which will last two years, will explore the the boundary between Earth and space (the ionosphere) to help scientists better understand the physical connection between Earth and the immediate space environment around it. Scientists have known for a long time that Earth’s ionosphere responds to “space weather” drivers from the sun, but recent NASA missions have surprisingly shown this variability often occurs in concert with Earth’s weather. ICON will compare the impacts of these two drivers as they exert change on the space environment surrounding Earth, and ultimately the mission’s findings will help improve forecasts for extreme space weather that can disrupt satellite and radio communications from orbiting communications spacecraft, such as the Global Positioning System (GPS).
“Though the solar inputs are now well quantified, the drivers of ionospheric variability originating from lower atmospheric regions are not. ICON is the first space mission to simultaneously retrieve all of the properties of the system that both influence and result from the dynamical and chemical coupling of the atmosphere and ionosphere,” notes UC Berkeley’s Space Sciences Laboratory (UCB/SSL). “ICON achieves this through an innovative measurement technique that combines remote optical imaging and in situ measurements of the plasma. With this approach, ICON gives us the ability to:
- Separate the drivers and pinpoint the real cause of ionospheric variability
- Explain how energy and momentum from the lower atmosphere propagate into the space environment
- Explain how these drivers set the stage for the extreme conditions of solar-driven magnetic storms.”
The spacecraft’s imaging capabilities, combined with its in-situ measurements, will provide scientists with a perspective of the coupled system that would otherwise require multiple satellites to gather the same information. Four sensitive instruments will give ICON the ability to carry out its mission:
MIGHTI, or the Michelson Interferometer for Global High-resolution Thermospheric Imaging, will determine thermospheric winds and temperatures. The EUV profiler, or Extreme Ultra Violet Imaging Spectrograph, will determine the altitude profile of the dayside ionospheric density through limb imaging in the extreme ultraviolet range. The FUV imager, or Far Ultra Violet Imaging Spectrograph, will determine daytime thermospheric composition and nighttime ion density through imaging the limb and sub-limb of the ionosphere-thermosphere. Lastly, the IVM, or Ion Velocity Meter, which consists of two planar thermal ion sensors, will provide measurements of the ion drift velocity in the spacecraft reference frame, the ion temperature, and the total ion number density at the location of the spacecraft.
Orbital was already contracted by UCB/SSL to design, manufacture, integrate, and test ICON, and now having secured a launch contract the company will also be responsible for spacecraft processing, payload integration, tracking, data and telemetry, and other launch support requirements. Berkeley operations engineers will work with the spacecraft engineers in all the initial tests and checkout, and the same can be said with the arrival of the scientific payload through integration of ICON with its rocket.
Currently manifested to fly in June 2017, ICON will employ Orbital’s Pegasus XL rocket, which has flown 42 times since 1990. Orbital’s Stargazer L-1011 aircraft will carry Pegasus and its 600-pound fully-fueled ICON payload to an altitude of approximately 40,000 feet before releasing them into free fall. After about five seconds the Pegasus will come to life, igniting its first stage solid-rocket motor and thundering above the Pacific Ocean to deliver ICON into a 27 degree inclination, 575 km circular orbit.
The Mission Operations Center (MOC) at UCB’s SSL will operate the ICON mission, same as they already do for all NASA Explorer missions, including THEMIS, ARTEMIS, RHESSI, and NuSTAR.
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