When Solar Orbiter launches, and how to watch it

An Atlas 5 rocket is scheduled take Solar Orbiter to space from a launchpad in Cape Canaveral, Fla. on Sunday at 11:03 p.m. Eastern, around the time this year’s Academy Awards ceremony will come to an end.

Forecasts currently call for a 90 percent chance of favorable weather, but if bad weather or technical problems arise, the launch can be pushed by as much as two hours into early Monday morning.

Both NASA Television and the European Space Agency will broadcast coverage of the launch, beginning at 10:30 p.m. Eastern.

ImageThe European-built Solar Orbiter spacecraft on Saturday atop the American-built Atlas 5 rocket that will carry it to space.
Credit…Steve Nesius/Reuters

A new view of the sun

With Solar Orbiter, scientists will for the first time get a good view of the top and bottom of the sun. Until now, almost all of the solar-watching spacecraft have orbited in the ecliptic, or the same plane that the planets travel around the sun.

That change of view could help solve mysteries about how the sun spews high-velocity charged particles that fly outward through the solar system and buffet the planets, including Earth. The magnetic fields that accelerate those particles flow into and out of the sun’s poles. The data from Solar Orbiter could help explain the sunspot cycle — Why does the cycle last 11 years? Why are some quiet and others roar violently? — and help models to predict solar storms that could disrupt Earth’s power grids and satellites in orbit.

Ulysses, an earlier collaboration between NASA and the European Space Agency launched in 1990, also passed over the sun’s poles, but at much farther distances, and it did not carry a camera.

A long and winding journey

The launch trajectory will take Solar Orbiter away from Earth into an orbit around the sun. A flyby of Venus on the day after Christmas will sap some of its energy and let it spiral closer toward the sun.

Additional flybys — one of Earth, two more of Venus — will further adjust the orbit, which will still be in the ecliptic, the plane of the orbits.

A flyby of Venus in 2025 will swing Solar Orbiter out of the ecliptic to an angle of 17 degrees. That is enough to get a good glimpse of the polar regions. Additional Venus flybys will increase the angle to 33 degrees.

The mission is expected to complete 22 orbits of the sun in 10 years.

Solar Orbiter’s instruments

The spacecraft’s 10 scientific instruments are a mix. Some measure what is happening directly around the spacecraft, like the magnetic fields and particles of the solar wind. Others take pictures of what is occurring on the sun.

Remember the caution that you should not look directly at the sun? Solar Orbiter’s cameras have to do just that, and at a distance where the sunlight is 13 times as intense. Three peepholes in the heat shield will open for 10 days at a time to allow the instruments to collect data. The assorted cameras also have heat-resistant windows (think of them as scientific sunglasses) as protection.

The cameras will look at a range of wavelengths of light, including ultraviolet and X-rays. Some of the cameras break the light into separate wavelengths to identify specific molecules. The coronagraph includes a disk to block out most of the light to look at what is going on in the sun’s outer atmosphere.

Magnetic fields and solar storms


A solar eruption as recorded by NASA’s Solar Dynamics Observatory spacecraft.CreditCredit…By Nasa’s Goddard Space Flight Center/sdo

Occasionally, the sun erupts giant amounts of particles known as coronal mass ejections. When such an eruption slams into Earth’s magnetic field, it generates surges of electrical current.

Solar scientists do not have reliable ways to predict such an eruption. The largest one known to hit Earth was the Carrington event in 1859, named after one of the people who observed an intensely bright spot on the sun where the eruption occurred. The surge caused some telegraph wires to catch fire.

When Nicola J. Fox, director of NASA’s heliophysics division, talks about solar science to children at schools she introduces the Carrington event and how it knocked out the telegraph system in the U.S. for four days.

“The kids just kind of look at me like, ‘So what?’,” she said. “And then I say, ‘Imagine you didn’t have your iPad for four days.’ Panic ensues in the classroom.”

A similar event today could potentially cause not only continentwide blackouts, but also destroy giant transformers on the electric grid — damage that might take months or years to repair.

A smaller solar storm in March 1989 knocked out power in Quebec for nine hours.

Just a few years ago, Earth was lucky.

On July 23, 2012, NASA’s Stereo-A spacecraft was hit by a gigantic coronal mass ejection. Analysis showed that this outburst was bigger than the Carrington eruption. If Earth had been where Stereo-A was — the spacecraft travels in the same orbit as Earth, but ahead of the planet — that would have been a very interesting day.

A partnership with Parker Solar Probe

In 2018, NASA launched the Parker Solar Probe, which is making closer and closer flybys of the sun as it reaches the fastest speeds ever achieved by a human-built spacecraft. That probe is flying into the sun’s outer atmosphere, known as the corona, and eventually coming within four million miles of its surface. By comparison, Earth is 93 million miles from the sun. Mercury, the closest planet, is 29 million miles from the sun.

The close distance allows the Parker Solar Probe to make direct measurements of those regions, but it has to be protected from temperatures of about 2 million degrees Fahrenheit.





Touching the Sun

From Aug. 2018: NASA’s Parker Solar Probe is flying through the punishing heat of the sun’s outer atmosphere.

“Set the controls for the heart of the sun.” In the summer of 2018, the Parker Solar Probe will lift off from Earth. It will spend the next seven years spiraling inward to the center of the solar system. The Parker probe will be the first spacecraft to touch our star. Or any star. It will brush through the halo of hot gases that form the sun’s outer atmosphere: the corona. The surface of the sun looks placid to our eyes, but it is pierced and roiled by strong magnetic fields. The fields trap gas blowing off the Sun and lift it into glowing arcs and streamers. Scientists don’t understand how the corona works, or why it’s hundreds of times hotter than the surface of the sun. The Parker probe will pass closer to the Sun than any mission before it. To get that close, the spacecraft will make seven flybys of Venus over seven years, gradually tightening its elliptical orbit and shifting it closer and closer to the sun. A high-tech heat shield will protect the probe from the punishing radiation and heat of the corona. Within the shield’s shadow, the spacecraft instruments will operate at a comfortable room temperature. As the probe passes close to the sun, it will briefly become the fastest machine ever built by humans, zipping along at a brisk 430,000 miles per hour. The Parker probe is the first NASA spacecraft to be named after a living person. Eugene Parker is an astrophysicist at the University of Chicago. In 1958, he suggested that the sun radiates a constant and intense stream of charged particles. He called it the solar wind. This wind pushes out comet tails and makes the long streamers seen in solar eclipses. With the Parker Solar Probe, scientists hope to learn more about the sun’s turbulent corona. How it accelerates particles, and how it flings huge clouds of fiery gas outward across space. Huge waves of magnetized gas are called coronal mass ejections. If Earth gets in the way of one of these storms, it could be bad news. Our planet is protected by its own magnetic field, but a direct hit from one of these galloping clouds of particles and radiation could disrupt satellites and force astronauts in the space station to take shelter. In 1859, a powerful storm called the Carrington Event produced auroras as far south as Cuba. A solar storm of that size today could cripple satellites and power grids around the world. If successful, the Parker probe’s mission to touch the sun may explain how solar storms form. Scientists hope it might teach us how to predict coronal outbursts more accurately and learn how to endure them. We’ve always depended on the kindness of a star, here on a planet riding the gentle fringe of barely calculable forces. Living with a star is not easy. But we’re learning.

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From Aug. 2018: NASA’s Parker Solar Probe is flying through the punishing heat of the sun’s outer atmosphere.

Solar Orbiter will be passing farther from the sun. At the closest point along its elliptical orbit, it will be just three million miles inside of the orbit of Mercury, and experience much less extreme temperatures. Instead of millions of degrees, temperatures at Solar Orbiter will reach several hundred degrees. That allows Solar Orbiter to carry a wider range of instruments.

Coordinated observations between Parker and Solar Orbiter could identify phenomena on the surface with conditions in the corona.

“It’s really a perfect dream, a marriage in heaven,” said Guenther Hasinger, director of science at European Space Agency during a news conference on Friday.

A slightly less busy rocket day

Solar Orbiter was not the only spacecraft scheduled to be launched from the East Coast on Sunday. A crewless Antares cargo ship with supplies, equipment and experiments destined for International Space Station was to lift off at 5:39 p.m. Eastern time from the Mid-Atlantic Regional Spaceport in Virginia. However, after a short postponement, Sunday’s launch was called off. Northrop Grumman, which manages the Antares and Cygnus flights, described a problem with a sensor on the ground. It said it will not be able to attempt a launch again until Thursday because of weather concerns as well as time needed to address the problem that caused the scrubbed launch.


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