Historic solar mission as probe aims to 'touch' the sun

AFP PHOTO, NASA, Johns Hopkins APL ¬| Handout illustration obtained July 6, 2018 courtesy of NASA/Johns Hopkins APL shows an artist’s conception of NASA’s Parker Solar Probe, the spacecraft that will fly through the Sun’s corona.

NASA’s newest spacecraft, the Parker Solar Probe, will now launch early Sunday on a mission through the sun’s scorching atmosphere to get closer than any probe has before.


At 7:33 GMT on Sunday morning a tiny spacecraft will launch from the biggest rocket of America’s National Aeronautics and Space Administration (NASA), pointed directly at the sun. The Parker Solar Probe will fly to within 4 million miles of the sun’s surface, confronting more extreme heat and cold than any spacecraft has before.

The probe was due to launch on Saturday morning, but the countdown was halted with less than two minutes remaining due to a last-minute technical hitch. Rocket maker United Launch Alliance said it would try again Sunday, provided the helium-pressure issue can be resolved quickly. As soon as the red pressure alarm for the gaseous helium system went off, a launch controller ordered, "Hold, hold, hold."

If all the technical issues are resolved, it will now launch 24 hours later than schedule. Once launched, the probe will have to contend with temperatures ranging from minus 235 degrees to 1500 degrees Celsius. It is named after Eugene Parker, an acclaimed American solar astrophysicist who in the 1950s proposed a number of concepts about how stars, including our sun, emit energy. He called this torrent of energy the solar wind. He also developed an explanation for the superheated solar corona, the sun’s atmosphere, which is surprisingly hotter than the sun’s actual surface.

The probe will make history as the first human-made object ever to plunge into the solar corona.

“Among our key aims for this project is to find out what makes the corona so hot – it is at least 300 times hotter than the surface of the sun,” said Justin C. Kasper, who is leading the international team of scientists and engineers building sensors that will collect samples from the sun. “We also want to discover what makes solar wind go so fast and then suddenly so slow; it can go up to a million miles an hour.”

This process officially started in 2010, but the seeds were firmly planted 15 years ago when Kasper and his team thought it might be a possibility and started developing instruments that would be able to endure the extreme conditions.

Staring straight at the sun

“One of the instruments we have created will have to stare directly at the sun at 1500 degrees Celsius. We have had to discover ways to expose the equipment here on earth and one of the key tests was using the largest solar furnaces in the world.”

The spacecraft and its instruments will be protected from the ferocious temperatures by a 4.5-inch-thick carbon composite shield. The shield will enable the instruments to operate at a comfortable 30 degrees Celsius.

Kasper explains that a lot of energy is required to even get this close to the sun: “Using a huge rocket launcher will help but it will not provide nearly enough energy, so we will need a lot of regular gravitational assistance from Venus.”

The spacecraft will have its first encounter with Venus this November and will then be orbiting the sun for seven fly-bys over up to seven years. The team is confident it will reach within 35 solar radii of the sun in the first orbit – each solar radius is 695,700 kilometres. But it will reduce the distance with each circuit and will ultimately be just 9.8 solar radii away from the sun, which is more than seven times closer than any spacecraft has come before.

Kasper says that there is an air of calm around the project, with just some last minute testing scheduled for Friday evening. “Our main worry now is the weather, this is the real unknown. A stray thunderstorm nearby when it launches could be seriously problematic. We will have to wait and see.”

You can follow the probe's progress on Twitter at @NASASun.

Daily newsletterReceive essential international news every morning