SPACE: A Soyuz crew launch suffers a rare abort seconds before liftoff.

On Thursday a crew of three people was due to launch on a Soyuz rocket, bound for the International Space Station.

However, the launch scrubbed at about 20 seconds before the planned liftoff time, just before the sequence to ignite the rocket’s engines was initiated, due to unspecified issues. Shortly after the abort, there were unconfirmed reports of an issue with the ground systems supporting the Soyuz rocket.

The three people inside the Soyuz spacecraft, on top of the rocket, were NASA astronaut Tracy C. Dyson, Roscosmos cosmonaut Oleg Novitskiy, and spaceflight participant Marina Vasilevskaya of Belarus. This Soyuz MS-25 mission had been planned for liftoff from the Baikonur Cosmodrome in Kazakhstan at 13:21 UTC (6:21 pm local time in Baikonur).

Such scrubs are rare. The Soyuz booster and its launch systems are typically robust, launching regardless of weather conditions—watching an orbital, liquid-fueled rocket launch during a snowstorm is quite a trip. And the Russians have plenty of experience with the booster. Since its debut in 1966, across a number of variants, the Soviet Union and Russia have launched more than 2,000 Soyuz rockets.

I’m curious to know what caused the scrub but don’t expect an honest answer out of Moscow.