Nasa’s Parker Solar Probe is now on the launch pad at Cape Canaveral, Florida. Its launch window will open at 3.48am (eastern daylight time, or 7.48am Greenwich mean time) on Saturday 11 August. Protected by a sophisticated heat shield the probe is designed to go closer to the sun than any previous spacecraft.
The probe’s mission is to dip into the solar atmosphere and deduce how the rarefied gasses there are heated to millions of degrees centigrade when the solar surface itself is just 6,000°C.
Following the launch the spacecraft will head towards Venus. Arriving on 2 October, it will use the gravity of the planet to then redirect towards the sun. Its first close solar approach will be on 5 November. This first pass will take place at a distance of 15m miles.
Successive flybys will be closer, culminating, in 2024, with a series of encounters just 3.8m miles above the sun’s surface.
If for any reason the spacecraft does not launch by 23 August it will have to wait until May 2019 for the next launch opportunity, when Earth and Venus will again be lined up correctly.