Nasa has held its first public meeting on UFOs, a year after launching a study into unexplained sightings.

The space agency televised the hours-long hearing featuring an independent panel of experts. The team includes 16 scientists and other experts selected by Nasa including retired astronaut Scott Kelly, the first American to spend nearly a year in space.

Workers on scaffolding repaint the NASA logo near the top of the Vehicle Assembly Building at the Kennedy Space Center in Cape Canaveral, Photo / John Raoux, AP, File

Several committee members have been subjected to “online abuse” for serving on the team, which detracts from the scientific process, said Nasa’s Dan Evans, adding that Nasa security is dealing with it.

“It’s precisely this rigorous, evidence-based approach that allows one to separate the fact from fiction,” Evans said.

The study is a first step in trying to explain mysterious sightings in the sky that Nasa calls UAPs, or unidentified aerial phenomena.

The group is looking at what unclassified information is available on the subject and how much more is needed to understand what’s going on in the sky, according to astrophysicist David Spergel, the committee’s chair who runs the Simons Foundation.

No secret military data is included, such as anything surrounding the suspected spy balloons from China spotted flying over the US earlier this year.

The meeting was held at Nasa headquarters in Washington with the public taking part remotely.

A final report is expected by the end of July.

- Marcia Dunn, AP