Some months ago I observed an object crossing the sky at night from Coventry UK. It crossed the entire extent of the sky in about 2 seconds. It was very high up and had a red glow like that of a jet afterburner. It didn't fade out or change brightness as you might expect of a meteor and wasn't white as you'd expect of a satellite. I wondered at the time if someone was testing a very fast military vehicle. It would be interesting to know what various nations are working on.