Updated It's yet another fateful day for upstart startup rocket biz SpaceX and its visionary founder Elon Musk. Today the company will attempt for the first time to put a satellite into a geostationary transfer orbit - and so enter the main space arena in which serious commercial money can be made today.

Geostationary orbit is the magic ring around the planet 35,786km above the equator, where a satellite in a stable trajectory goes round the planet in exactly 24 hours and thus hovers stationary above a point on the surface. This means that a dish pointing at such a satellite does not need to move to track it, and the satellite is always there.

That makes the satellite hugely more valuable for most commercial purposes than one which barrels briefly across the sky as it will if placed in low orbit. So, though it takes a lot more rocket poke to get up to GTO, the satellite operator will pay a lot, lot more to the launch provider. In fact the bulk of the commercial, private sector space launch market - by money, if not by numbers of satellites - is geostationary. The belt of spacecraft circling the Earth almost 36,000km out is effectively the Money Ring for those who want to make a commercial buck in space today (though if you don't mind working for the government it may be more lucrative still to focus on putting large payloads into low polar orbits, as SpaceX also hopes to do).

Today, SpaceX aims to send up a Falcon 9 rocket from Cape Canaveral and deliver a communications bird for satellite multinational SES to the point on the Money Ring 95 degrees east of Greenwich, where it will bring various services to southern Asia. The launch window opens at 5:37pm Eastern US time (10:37pm GMT).

The company says:

SES-8 will be SpaceX’s first launch to a geostationary transfer orbit ... and most challenging mission to date.

The launch will be streamed live by SpaceX here.

Say what you like about Elon Musk and/or SpaceX, there's never a dull moment with them around. ®

Updated at 2355 GMT, 1555 PT

The launch was scrubbed: more information right here.