Mission to touch the Sun

In 2018, NASA launched a thrilling mission unlike any other to date. From Cape Canaveral, the Parker Solar Probe was scheduled to launch within a small window between 31 July and 19 August on a 7-year journey to the Sun to learn more about our star.

Rights: NASA/John Hopkins University Applied Physics Laboratory

Parker Solar Probe

NASA’s Parker Solar Probe aims to collect data that will help us better understand and forecast space weather.

The scientific goals include to:

• determine the structure and dynamics of the magnetic fields at the sources of solar wind
• trace the flow of energy that heats the corona and accelerates the solar wind
• determine what mechanisms accelerate and transport energetic particles
• explore dusty plasma near the Sun and its influence on solar wind and energetic particle formation.

In 2024, the probe will enter the Sun’s atmosphere and will pick up where other missions have left off in trying to understand our star better. We have been observing the Sun for a long time, but finally, technology has advanced so that we can send a probe closer than ever before and retrieve data.

From the moment the probe enters its orbital pattern, it will be making measurements. The mission aims to learn more about the Sun’s magnetic field, how the surface plasma is flowing, why there are solar flares and mass ejections and where the ejections come from. There is much we have observed about the Sun but still don’t fully understand.

To get to its place near the Sun, the probe needs to be going very fast so that it doesn’t pulled in by the Sun’s overwhelming gravity. Earth goes around the Sun at around 100,000 kilometres per hour – the probe will have to orbit at 700,000 kilometres per hour to gain angular momentum and avoid plunging into the Sun. To get to the Sun at this speed, the probe will fly by Venus seven times for gravity assists, getting faster and faster each time. Its orbit will take the probe between the solar atmosphere and all the way out to the orbit of Venus, orbiting the Sun in an ellipse, not a circle. It will complete that orbit in 88 days – the same length of time it takes Mercury to get around the Sun, so it’s travelling faster than Mercury (it has further to go).

Rights: NASA/John Hopkins University Applied Physics Laboratory

Parker Solar Probe trajectory design

The probe will use seven Venus fly-bys, using gravity assists to gain speed. It will have to orbit at 700,000 kilometres per hour to gain angular momentum to avoid plunging into the Sun.

The probe will orbit just 6.2 million kilometres from the Sun (for perspective, Mercury is 57.91 million kilometres from the Sun), in a scorching environment of about 1,377°C. Unlike other missions to the far distances of the Solar System, this probe has no shortage of solar energy to power it! It has an abundance of solar energy, along with extreme heat and radiation. A 2.4 metre wide, 4.5 inch thick carbon composite shield will protect the probe in its orbit around the Sun. There are two photovoltaic arrays to collect power for the probe. The primary array will extend at certain distances from the Sun and retract behind the shield when the probe gets close the Sun. The secondary, smaller array will operate at the closer distances. There is a fluid cooling system that runs through the secondary array to keep it operational at the extreme temperatures.

The Sun

Although our nearest star, large and bright in our sky, the Sun still holds scientific secrets. Scientists also want to know why the corona is hotter than the surface and why there is a solar wind and to learn more about the surface of the Sun. The surface is like nothing else that exists anywhere in the universe (other than on other stars). Stars have fluid dynamics, and the surface doesn’t fit into the solid-liquid-gas categorisation. It is plasma – a gas acting as a liquid. The mission will also seek to answer questions about the cycle of solar maximum and minimum and what the effects of a major solar event would be here on Earth. Information from this mission will also help to understand other star systems and the possible conditions on exoplanets in the ‘Goldilocks zone’.

Rights: Stefan Seip

A solar prominence

A solar prominence is a cloud of gas held just above the surface of the sun by its magnetic field.

Space missions are always ground-breaking, and this mission to ‘touch the Sun’ is no different. There will be extensive information for STEAM-based classroom activities on NASA’s website so students can learn along with the mission.

Rights: Stardome Observatory and Planetarium

Stardome Observatory and Planetarium

Stardome's mission is to be a trusted centre for sharing astronomy and mātauranga in Tāmaki Makaurau Auckland.