NASA Scientists Plan Mission To The Sun

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"The sun has a variable magnetic field. We're going to learn a lot about that," Fisher said. "It also emits particles. There are two kinds of streams from the Sun; there's a fast wind and a slow wind. We're going to use the whole system as a laboratory. We're going measure the physical effects, which is something you ordinarily sense by using a telescope."

For the mission, NASA will send a car-sized spacecraft four million miles from the sun's surface, far closer than any planet -- the closest, Mercury, has an orbital radius of 57 million miles. Using a gravitational push from Venus, the spacecraft will gradually get closer to the sun over a seven-year period, reaching its closest approach by 2025.

The area which the spacecraft will be studying, the Sun's plasma atmosphere, is called the corona. It's here where the two types of solar wind form. The slow wind, which is "gusty," Guhathakurta says, has a number of effects on Earth-based systems.

"It has consequences for satellites, airplanes and astronauts exploring space. [Solar winds] can harm satellites, harm astronauts. They produce the aurora borealis. To understand what is happening on the sun and why this happens, we need to go to the source," Guhathakurta said.

Throughout the mission, robotically controlled instruments collect the data on the Sun's outer surface and a radio link will send it to the science operations center back on Earth.

Money and technology are the reasons this mission hasn't been tried before. A spacecraft venturing that close to the sun's surface must be able to withstand temperatures of 2,550 degrees Fahrenheit and blasts of intense radiation. It is only recently that the materials necessary to build such a probe were cheap enough to be practical.

"Our job is to make it fit in the budget," Fisher said. Initial estimates from NASA say the spacecraft will cost approximately $180 million. By contrast, the Viking missions to Mars and the Voyager programs both came in at nearly $1 billion each.

"You have to have a shield which keeps radiants of the sun off the instruments," Fisher said. To do this, the spacecraft will have a thermal protection system, which is a large, flat carbon shield 2.7 meters in diameter.

Initially, the project was going to be powered by a nuclear generator, but hte cost proved too high. Instead, it will be powered by two separate solar array systems. It will also feature guidance and control system that uses three star trackers, an internally redundant inertial measurement unit and a solar horizon sensor.

With the design concept in place, the hard part begins for NASA scientists working on the project.

"Our launch date is August 2018," John Lee, executive director of the project, said. "We have eight years to get the craft ready. We're in phase A of the development, which is the formulation phase. That happens over four years. After formulation is implementation and then after that comes the launch."