After successfully launching Thursday night, NASA’s Ionospheric Connection Explorer (ICON) spacecraft is in orbit for a first-of-its-kind mission to study a region of space where changes can disrupt communications and satellite orbits, and even increase radiation risks to astronauts.
A Northrop Grumman Stargazer L-1011 aircraft took off at 8:31 p.m. EDT from Cape Canaveral Air Force Station in Florida carrying ICON, on a Northrop Grumman Pegasus XL rocket, to launch altitude of about 39,000 feet (12,000 meters). The first launch opportunity around 9:30 was skipped due to communication issues between the ground team at Cape Canaveral and the aircraft. On the second attempt, the aircraft crew released its payload at 9:59 p.m. EDT and automated systems on the Pegasus rocket launched ICON, a spacecraft roughly the size of a refrigerator, into space.
The spacecraft’s solar panels were successfully deployed, indicating it has power with all systems operating. After an approximately month-long commissioning period, ICON will begin sending back its first science data in November.
ICON will study changes in a region of the upper atmosphere called the ionosphere. In addition to interfering with communications signals, space weather in the ionosphere can also prematurely decay spacecraft orbits and expose astronauts to radiation-borne health risks. Historically, this critical region of near-Earth space has been difficult to observe. Spacecraft can’t travel through the low parts of the ionosphere and balloons can’t travel high enough.
“ICON has an important job to do – to help us understand the dynamic space environment near our home,” said Nicola Fox, director for heliophysics at NASA Headquarters in Washington. “ICON will be the first mission to simultaneously track what’s happening in Earth’s upper atmosphere and in space to see how the two interact, causing the kind of changes that can disrupt our communications systems.”
ICON explores the connections between the neutral atmosphere and the electrically charged ionosphere with four instruments. Three of the instruments rely on one of the upper atmosphere’s more spectacular phenomena: colorful bands called airglow.
Airglow is created by a similar process that creates the aurora – gas is excited by radiation from the Sun and emits light. Though aurora is typically confined to extreme northern and southern latitudes, airglow happens constantly across the globe, and is much fainter. But it’s still bright enough for ICON’s instruments to build up a picture of the ionosphere’s density, composition, and structure. By way of airglow, ICON can observe how particles throughout the upper atmosphere are moving.
ICON’s fourth instrument provides direct measurements of the ionosphere around it. This instrument characterizes the charged gases immediately surrounding the spacecraft.
“We put as much capability on this satellite that could possibly fit on the payload deck,” said Thomas Immel, the principal investigator for ICON at the University of California, Berkeley. “All those instruments are focused on the ionosphere in a completely new science mission that starts now.”
ICON’s orbit around Earth places it at a 27-degree inclination and altitude of about 360 miles (580 kilometers). From there, it can observe the ionosphere around the equator. ICON will aim its instruments for a view of what’s happening at the lowest boundary of space, from about 55 miles (90 kilometers) up to 360 miles (580 kilometers) above the surface. This rapid orbit circles Earth in 97 minutes while precessing around the equator, allowing ICON to sample a wide range of latitude, longitude, and local times.
ICON is an Explorer-class mission. NASA’s Goddard Space Flight Center in Greenbelt, Maryland, manages the Explorer Program for NASA’s Science Mission Directorate in Washington. The University of California at Berkeley developed the ICON mission and the two ultraviolet imaging spectrographs, Extreme Ultra-Violet instrument and the Far Ultra-Violet instrument. The Naval Research Laboratory in Washington developed the Michelson Interferometer for Global High-resolution Thermospheric Imaging instrument. The University of Texas in Dallas developed the Ion Velocity Meter. The spacecraft was built by Northrop Grumman in Dulles, Virginia. The Mission Operations Center at UC Berkeley’s Space Sciences Laboratory is tasked with operating the ICON mission.
ICON – Spacecraft and Instruments
The ICON science payload sits on an Orbital ATK LEOStar-2 spacecraft. With the payload attached, the spacecraft weighs approximately 600 pounds (270 kilograms) and measures 3 feet by 6 feet (1 meter by 2 meters).
ICON will fly in an orbit around Earth at a 27-degree inclination and at an altitude of some 360 miles. This places it in a position to observe the ionosphere around the equator. ICON will aim its instruments for a view of what’s happening at the lowest boundary of space at about 55 miles (90 kilometers) up to 360 miles (580 kilometers).
ICON carries four instruments to collect images of the ionosphere and to directly measure characteristics of the space environment through which it flies. Together, the suite of instruments offers a perspective that would otherwise require two or more orbiting spacecraft. The instruments will provide the first comprehensive look at this crucial region to help scientists understand – and someday predict – what drives disturbances in the ionosphere.
ICON’s four instruments:
- MIGHTI: The Michelson Interferometer for Global High-resolution Thermospheric Imaging instrument observes the temperature and speed of the neutral atmosphere. These winds and temperature fluctuations are driven by weather patterns closer to Earth’s surface. In turn, the neutral winds drive the motions of the charged particles in space. MIGHTI is built by the Naval Research Laboratory in Washington, DC.
- IVM: The Ion Velocity Meter will observe the speed of the charged particle motions, in response to the push of the high-altitude winds and the electric fields they generate. The IVM is built by the University of Texas at Dallas.
- EUV: The Extreme Ultra-Violet instrument captures images of oxygen glowing in the upper atmosphere, in order to measure the height and density of the daytime ionosphere. This helps track the response of the space environment to weather in the lower atmosphere. EUV is built by the University of California at Berkeley.
- FUV: The Far Ultra-Violet instrument captures images of the upper atmosphere in the far ultraviolet light range. At night, FUV measures the density of the ionosphere, tracking how it responds to weather in the lower atmosphere. During the day, FUV measures changes in the chemistry of the upper atmosphere — the source for the charged gases found higher up in space. FUV is built by the University of California at Berkeley.