Solar Probe Orbiter To Move Closer To Sun Than Mercury In 2017

NASA yesterday announced it has chosen United Launch Services to lift the Solar Orbiter probe into space in 2017 to study the Sun and its outer atmosphere.

And a follow-on project, Solar Probe Plus, has moved into a stage of advanced development for its bid to fly even closer to the furnace at the heart of our Solar System.

The Solar Orbiter mission is a collaboration between NASA and the European Space Agency that will aim to produce high resolution images of the activity in the atmosphere and combine these observations with measurements of the flow of the solar wind around the probe.

With this new generation of missions we will get very close to the Sun, which is crucial for building a complete understanding of how the Sun creates and controls the solar wind

Solar Orbiter will get its close-up views by flying to within 45 million kilometres of the Sun, which is closer than Mercury. As it flies, it will also take images of the Sun’s poles to help scientists understand how our local star generates its magnetic field.

The satellite is being built by Astrium UK from parts supplied from across Europe and instruments developed in Belgium, France, Germany, Italy, Spain, Switzerland, the UK, and the US.

NASA has put the cost of launching Solar Orbiter at about $172.7 million. It will be launched atop an Atlas V 411 rocket from Space Launch Complex 41 at Cape Canaveral Air Force Station, Florida.

Solar Probe Plus is an even more daring mission because it aims to swoop considerably closer over the Sun than Orbiter will as it seeks to study the corona, that atmospheric glow that we get to see during a total eclipse.

The mission’s project manager Andrew Driesman said: “Solar Probe Plus will fly closer to the sun than any spacecraft before it — almost ten times closer to the sun than the planet Mercury — and this presents unprecedented technical challenges.”

Driesman is leading the team at the Johns Hopkins University Applied Physics Laboratory (APL) in Maryland that will now begin advanced design, development and testing for the Solar Probe Plus mission, following a successful design review by an independent assessment board.

He added: “Whether it was devising ways for a spacecraft to survive so close to the sun, or to collect data in such an extreme environment, the concept of an operational solar probe had challenged engineers and scientists for decades, and now we’re another step closer to making it happen.”
Solar Probe Plus, which is set to launch in 2018, will orbit the Sun 24 times, using seven flybys of Venus to help it close in on it. At its closest passes, it will speed at 190 km per second (118 miles per second) through the Sun’s outer atmosphere, or corona.

That will bring it to around 6.2 million kilometres (3.8 million miles) from the Sun’s visible surface which is a little more than four times the Sun’s diameter. It will explore a region, and accompanying hazards, that no other spacecraft has encountered.

With a shield to protect them from searing temperatures approaching 1,400 C (2,500 F), its ten science instruments will seek to discover why the Sun’s outer atmosphere is so much hotter than the surface, and what accelerates the solar wind out into space.

“The answers to these questions can be obtained only through in-situ measurements of the solar wind down in the corona,” says APL’s Nicky Fox, Solar Probe Plus project scientist. “Solar Probe Plus gets close enough to provide the missing links, with the right complement of instruments to make the measurements. For the first time, we will be able to go up and touch our star.”

Solar scientist Dr Lucie Green, of the UK’s Mullard Space Science Laboratory, and a regular presenter of the BBC’s The Sky At Night, is a Co-investigator on the Solar Orbiter mission. She told Sen: “At the start of the space age we discovered that our Sun is constantly sending a gusty flow of magnetic field and electrically charged gas into the Solar System, known as the solar wind. More recently we realised that this flow creates space weather at the Earth, affecting all of us.

“With this new generation of missions we will get very close to the Sun, which is crucial for building a complete understanding of how the Sun creates and controls the solar wind. It will mean that we can find out what process are taking place in the space between the Sun and us and how this modifies the wind. Solar Orbiter will give us the “missing link” in our understanding.”

Sen