WALLOPS ISLAND, Va. (WAVY) — NASA Wallops postponed the launch of a second sounding rocket after the first rocket launched at 6:21 a.m. Wednesday experienced an “anomaly.”

NASA didn’t elaborate on what the anomaly was, but said it was enough to put the second launch on pause. They said they’re investigating the cause and a new launch date has not been set.

NASA had rescheduled the launches to Wednesday from an earlier date because of unfavorable weather conditions and poor ocean conditions.

The sounding rockets were meant to carry student experiments into suborbital space. They’re smaller than the Antares rocket that launched earlier this month for an International Space Station resupply mission.