Nasa Mars launch 2020: What time is it, how can I stream it online and what is happening?

Rocket must liftoff within specific window – or be forced to wait for more than two years

The Atlas 5 rocket carrying the Mars InSight probe launches from Vandenberg Air Force Base, as seen from the San Gabriel Mountains more than 100 miles away, on May 5, 2018 near Los Angeles, California (David McNew/Getty Images)

Nasa is about to head to Mars, sending its best rover yet to look for signs of ancient alien life.

The launch window is due to open today, 30 July, and mission controllers must take advantage of the relatively brief time they have or be forced to delay the launch for two years.

Everything is said to be on schedule for the launch, with Nasa engineers having tested everything possible and the United Launch Alliance – the partnership between Lockheed Martin and Boeing that built the rocket – indicating that everything is running as it should be.

The rocket is expected to launch at 7.50am local eastern time in Florida, where the rocket will take off from a launchpad at Cape Canaveral Air Force Station. That time is 12.50pm in the UK.

Each of the launch windows runs for two hours, with opportunities every five minutes. As such, if the rocket does not take off by 9.50am local time, mission controllers will be forced to push the launch back.

But they will not be able to push back the launch too far. The rocket has a broader launch period of about three weeks, which ends on 15 August.

If mission controllers miss that launch period, the rocket will be unable to go at all. Instead, it will have to wait for more than two years until the planets align again to allow for a launch.

It's that relatively brief planetary alignment that has made this the "Summer of Mars", as the UAE and China also took advantage to launch their missions to the planet. The European Space Agency and Roscosmos had also planned to send their Rosalind Franklin rover, but missed their schedule and have been forced to wait until 2022.

The chance that Nasa will miss its chance today is low, however. Official forecasts give a 20 per cent chance of "violating weather constraints" – or bad conditions – with the main worries being clouds above the launchpad.

The launch can be watched live on a variety of platforms. Information on those can be found here.

The mission will see Nasa look for evidence of ancient alien life on the Martian surface. A full round-up of how it will do that can be found here.

The Independent will be liveblogging the whole launch. You can find our up-to-the-minute coverage here.