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Future NASA mission to sun is 'a life's dream' for some

The Solar Probe Plus, due to launch in 2018, will fly much closer to the sun than any predecessor in search of answers about its corona and solar wind.

March 11, 2012|By Amina Khan, Los Angeles Times
  • The Solar Probe Plus mission's up-close look at the sun may ultimately help scientists predict solar flares, such as this one photographed several days ago.
The Solar Probe Plus mission's up-close look at the sun may ultimately… (NASA )

The chest-high rack of electronics Justin Kasper is assembling in a Massachusetts office park will fit in a shoe box before he's done.

It won't be much to look at — a few inches across, shaped rather like a coffee cup attached to a Kindle — but to Kasper, it'll serve as eyes across nearly 100 million miles of space.

In less than seven years, that cup will be journeying to the center of the solar system to scoop up bits of the sun.

"This really has been a life's dream," said Kasper, of the Harvard-Smithsonian Center for Astrophysics in Cambridge, Mass.

In 2018, NASA is scheduled to launch a spacecraft from Cape Canaveral Air Force Station in Florida to fly, Icarus-like, dangerously close to our star.

Fitted with a select set of instruments, Solar Probe Plus will address two questions that solar physicists have tussled with for decades: How does the corona, that ghostly, spiked halo seen during a total solar eclipse, heat to more than a million degrees, far hotter than the sun's surface? And what powers the solar wind, the stream of charged particles that flows from the corona?

An up-close look at the sun may ultimately help scientists predict solar flares, as well as coronal mass ejections — "solar storms" like those launched at Earth last week. These events send a barrage of high-energy particles crashing against the Earth's magnetic field, at times disabling satellites, wiping out power grids, forcing airlines to reroute flights and potentially exposing astronauts to fatal doses of radiation.

Scientists have sent probes to the solar system's edge, but never so near its heart. Coming within 3.7 million miles of the sun's surface — 25 times closer than Earth — the 1,350-pound unmanned spacecraft will heat to 2,600 degrees Fahrenheit and endure 512 times the sunlight of vessels orbiting Earth. It is expected to make its first approach from that distance in 2024.

The mission "will undoubtedly have impact on our ideas about how life operates throughout the universe — if life does operate throughout the universe — how our planet evolved and how we're going to contend with the further exploration of space," said Richard Fisher, director of NASA's heliophysics division.

Half a century in the making, with an estimated price tag of $1.2 billion and barely 88 pounds allotted to experimental hardware, the project spawned fierce competition among heliophysicists for a piece of the action.

In September 2010, Kasper learned that his proposal to count the electrons, protons and helium ions in the solar wind had won one of five coveted spots. He happily ripped open boxes filled with commemorative copies of the proposal — he'd let them gather dust for months, afraid to jinx his chances — and passed them out to his team.

Now, with the instruments selected and the project's next phase underway, some researchers are elated while others tussle with a mix of emotions: sadness at being left out and excitement at what their field stands to learn.

Other spacecraft have ventured toward the sun before: In 1976 the Helios 2 mission came within 27 million miles. The European Space Agency plans to launch a solar orbiter in 2017 that will come as close as 26 million miles.

But Solar Probe Plus, to be built by the Johns Hopkins University Applied Physics Laboratory, is more ambitious by far, venturing seven times closer.

Scientists have talked of such a journey since the 1950s, but plans were always logistically fraught and prohibitively expensive.

They had wanted to study the solar poles because the sun's magnetic field would be strongest there. But this meant flying over and under the sun rather than girdling its middle like the planets, requiring huge amounts of energy.

The proposed solution: Send the probe to Jupiter, whose gravity would twice lob it back toward the sun, over its north pole and under its south pole.

But sending a probe to such cold, dark reaches of space would require nuclear power — not just solar — and thus a heavy cooling system. Costs mounted.

Time and again, the mission was revived and then shelved.

"Always off again and on again," said retired solar astrophysicist Eugene Parker. "It came to be a standing joke."

It was time to rip up the plans and start over.

A thought struck the scientists charged with going back to the drawing board.

"I kept staring at the mission's scientific objectives, which have been around for a long, long time," said Andrew Dantzler, who oversaw civilian spaceflight projects at Applied Physics Laboratory until his death in October. "The word 'polar' wasn't in any of the objectives. So I had to go back and ask, 'Why are we visiting the poles again?'"

That question inspired a totally new idea: Give up on the poles. Swing the craft a few times around Venus and then to the sun, to end up circling its middle.

And everything seemed to fall into place.

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