Ahead of today's first practice session the air temperature is 15 degrees C, while the track temperature is 18 degrees. This might be Texas but it is unseasonably cool.

The tyres available this weekend are the same as in 2012 for the inaugural race, hard and medium.

Unlike 2012 there are two DRS zones, one on the pit straight while the other, as in 2012, runs between Turns 11 and 12.

Of course, the big news that Heikki Kovalainen replaces fellow Finn Kimi Raikkonen at Lotus, the 2007 world champion heading off for back surgery ahead of his return to Ferrari.

Other than the experienced Kovalainen, another driver who will be keenly watched this morning is Daniil Kvyat who replaces Daniel Ricciardo at Toro Rosso next season. Having gained his superlicence last week the Russian teenager is taking part in FP1 here and again in Brazil next week.

The other reserve drivers in action this morning are Alexander Rossi - replacing Giedo Van der Garde - at Caterham, and Rodolfo Gonzalez - replacing Jules Bianchi - at Marussia.

Surprisingly, the start of the session is delayed for ten minutes due to fog over the circuit which means the medical helicopter cannot take off. One does not expect fog in Austin, Texas. Indeed, as the TV cameras the crowd one would be forgiven for thinking we're at Silverstone.

At 9.05 officials announce a further ten minute delay.

In the Red Bull garage, Vettel does well to close a (clearly important) note pad as the FOM camera closes in...

At 9.15 a further ten minute delay is announced, which means the session will now run for just one hour.

In the Lotus garage, Lewis Hamilton welcomes Kovalainen back to the business end of the pitlane. Elsewhere, Mark Webber chats with former teammate Fernando Alonso.

At 9.25, yep, you've guessed it… another ten minutes. The medical car is on track, but this is all about the medical helicopter. Jean-Eric Vergne tweets that this is "not a bad FP1 to miss".

Satisfied that all is now ok, officials announce the session will get underway at 9.40 and last for one hour.

The fog has given way to bright blue sky, even if it is on the chilly side.

The lights go green and Kovalainen leads the way, followed by Hulkenberg, Gutierrez, Alonso, Massa, Chilton, Kvyat, Ricciardo and Grosjean.

While most return to the pits following their installation lap, Kovalainen stays out. Vettel's car features the rotating camera first witnessed in Abu Dhabi.

Lots of drivers sporting new - or one-off - helmet liveries this weekend, including Hamilton whose lid features a tribute to Michael Jackson.

Button posts the first time of the weekend, the McLaren driver stopping the clock at 1:41.943. As the Englishman improves to 40.468, Rossi posts 54.688.

Returning to his pit slot, Hamilton complains about the amount of "furniture" in the way.

Perez goes second with a 42.295, the Mexican looking understandably down since yesterday's official announcement regarding Kevin Magnussen.

Ten minutes into the session, all but the Force India duo have been out.

After reporting understeer, Button pits for a change to his front wing flap. Elsewhere, a big lock-up for his McLaren teammate who is informed that he's quicker than Button in S2.

As Hulkenberg goes third (43.036) the red flags are waved but it is not clear why.

As the camera picks up on an empty helicopter parking spot it is revealed that the session has been stopped due to "further problems with the medical helicopter".

Rob Smedley to Massa: "Pic and that, ugh, guy driving the Toro Rosso (Kvyat), has just passed now, behind you is a big gap."