Launch of NASA's spacecraft to study edge of Earth's atmosphere delayed again

NASA and Northrop Grumman were preparing for the launch of a spacecraft designed to study Earth's electrically charged upper atmosphere that was supposed to happen Wednesday, but was delayed shortly after the plane carrying the spacecraft took off.

Northrop Grumman was preparing to launch NASA's Ionospheric Connection Explorer, or ICON, spacecraft aboard the Pegasus XL rocket around 3:05 a.m., but scrubbed it due to an issue with data on the rocket, according to NASA officials.

NASA officials said in a tweet that the next launch opportunity is Thursday, which is the last day of the available launch window for ICON this month.

The spacecraft will study the area between Earth and space, known as the ionosphere. Astronauts living on the International Space Station have a bird's-eye view of the the swirling lights, known as airglow, produced in this area of Earth's upper atmosphere.

The spacecraft was slated to liftoff three weeks ago, but NASA delayed the launch for further testing on the Pegasus XL rocket.

On Tuesday, NASA and Northrop Grumman completed their launch readiness review at Kennedy Space Center and there were no technical issues, officials said.

Despite launching from the Space Coast, the Pegasus won't be visible from the ground.

The Northrop Grumman Pegasus XL rocket will catch a ride into the sky strapped to the belly of an aircraft known as the "Stargazer." The plane will take off from Cape Canaveral Air Force Station and release the rocket about 7 miles over the Atlantic Ocean. Pegasus will then free-fall for a few seconds before igniting its rocket motor and carrying ICON into orbit in just over 10 minutes.

However, NASA will still carry a launch livestream at nasa.gov/live  when the launch happens.

Air Force weather officials are predicting a 90 percent chance of favorable weather for the 3:05 a.m. flight. The primary weather concerns are cloud cover.

Northrop Grumman both built the spacecraft and is the launch vehicle provider.

Pegasus has launched more than 40 small satellites in 20 years with a perfect record, according to officials with Northrop Grumman.

Three things to know about ICON's mission

Why: ICON will study the ionosphere. This zone is where GPS signals and radio communications travel, and NASA wants to understand how gases in the ionosphere can affect those technologies.

Where: Looking down on Earth from the International Space Station — about 300 miles above the planet -- Earth’s upper atmosphere is a swirl of red, green, purple and yellow. Similar to auroras, that beautiful light is known as airglow, which happens as atoms and molecules shed excess energy as they meet sunlight, according to NASA.

What: ICON will look at airglow to learn more about how interactions between charged particles can affect technology on Earth and how airglow can reveal patterns.

“Each atmospheric gas has its own favored airglow color, depending on the gas, altitude region and excitation process, so you can use airglow to study different layers of the atmosphere,” said Doug Rowland, an astrophysicist at NASA’s Goddard Space Flight Center in Greenbelt, Maryland. “We’re not studying airglow per se, but using it as a diagnostic.”

The more you know: Another NASA mission, GOLD, led by a former University of Central Florida professor, is also currently studying Earth’s upper atmosphere. While ICON focuses on how charged particles and gases interact with the ionosphere, GOLD is observing what causes change between Earth and space.

The two missions will work in tandem to help scientists answer questions about this area of Earth’s atmosphere.

Space Sciences Laboratory at University of California Berkeley leads the scientific development and research behind ICON.

Check back for updates Tuesday night before the launch and after liftoff Wednesday morning.