Page 29 - All About Space 68 - 2017 UK

Mission to touch the Sun

PSP member says…
"The solar probe is going to a region of space
that has never been explored before. It's very
exciting that we'll finally get a look."
J. Felipe Ruiz
We hope that the Parker Solar
Probe will allow us insight into the Deputy lead mechanical engineer
Sun and the plasma waves it emits

paper on the topic was even rejected by a couple Beyond the supersonic threshold, information
of referees before being confirmed by observations cannot flow back towards the Sun but can only flow
a few years later. Professor Parker quite literally outward. This 'information' could relate to an obstacle
wrote the book on the solar wind, and will be 97 or event within the flow, rather like the way traffic
when his namesake spacecraft makes its first close congestion on a motorway can be detected further
approach to the Sun in December 2024. Among his back of any actual blockage.
key predictions was that the charged particles and In the inner part of the corona, the solar wind is
plasma streaming from the Sun would be accelerated expected to remain 'coupled' to the Sun and rotate
to supersonic velocities as they expanded into space. in time with it. Further out it moves radially, directly
But wait a second – how can there be a speed of away from the star. Somewhere between these two
sound in the silent vacuum of space? The head of the conditions is the transition zone, where the solar
Heliospheric Physics Laboratory at NASA's Goddard wind is given a huge burst of acceleration. "We
Space Flight Center, Dr Adam Szabo, clarifies: "The expect the solar wind to be as slow as 200 to 300
term is really a generalisation in the solar wind," kilometres per second (450,000 to 600,000 miles
he tells All About Space. "Although there are sonic per hour)," says Dr Szabo, "which is about half of what
waves, 'supersonic' really refers to a bulk flow it is at 1 AU [at Earth's orbit], but more importantly,
speed faster than any waves – including the fastest the speed of the waves will go up with the higher The solar shield, at the front of the spacecraft, is
electromagnetic waves – can travel in the medium". densities and stronger magnetic fields.” He continues: made of reinforced carbon-carbon composite

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