text: Nasa has finalised an ambitious mission to send a spacecraft closer to the sun than ever before. The Solar Probe Plus will carry four experiments into the corona and study the solar wind and energetic particles as they blast off the surface of the star . During the closest passes around the sun, temperatures outside the spacecraft will reach nearly 2,500 degrees Fahrenheit. Scroll down for video . Solar Probe Plus will carry four instrument suites into the corona and study the solar wind and energetic particles as they blast off the surface of the star. The launch window opens for 20 days starting on July 31, 2018. Over 24 orbits, the mission will use seven flybys of Venus to reduce its distance from the sun. The closest three will be just 3.8 million miles from the surface of the star. Solar Probe Plus is scheduled to launch aboard a United Launch Alliance Delta 4-Heavy rocket with an upper stage from Cape Canaveral Air Force Station, Florida. The launch window opens for 20 days starting on July 31, 2018. Over 24 orbits, the mission will use seven flybys of Venus to reduce its distance from the sun. The closest three will be just 3.8 million miles from the surface of the star. Scientists have long wanted to send a probe through the sun’s outer atmosphere, or corona, to better understand the solar wind and the material it carries into our solar system. The primary science goals for the Solar Probe Plus mission are to trace the flow of energy and understand the heating of the solar corona and to explore the physical mechanisms that accelerate the solar wind and energetic particles. To meet those objectives, Solar Probe Plus will carry four instrument suites into the corona and study the solar wind and energetic particles as they blast off the surface of the star. These instruments will study magnetic fields, plasma, and energetic particles, and will image the solar wind. The spacecraft and instruments will be protected from the sun’s heat by a 4.5-inch-thick carbon-composite shield. During the closest passes around the sun, temperatures outside the spacecraft will reach nearly 2,500 degrees Fahrenheit. How it will get there: Over 24 orbits, the mission will use seven flybys of Venus to reduce its distance from the sun. The small car-sized spacecraft will plunge directly into the sun's atmosphere approximately four million miles from our star's surface. It will explore a region no other spacecraft ever has encountered. The mission - which will fly closer to the sun than any spacecraft has before - reached a major milestone last month when it successfully completed its Critical Design Review, or CDR. An independent NASA review board met at the Johns Hopkins University Applied Physics Laboratory, or APL, in Laurel, Maryland, March 16-20, 2015, to review all aspects of the mission plan. APL has designed and will build and operate the spacecraft for NASA. The CDR certifies that the Solar Probe Plus mission design is at an advanced stage and that fabrication, assembly, integration and testing of the many elements of the mission may proceed. Solar Probe Plus will carry four instrument suites into the corona and study the solar wind and energetic particles as they blast off the surface of the star. These instruments will study magnetic fields, plasma, and energetic particles, and will image the solar wind. Wide-field Imager: principal investigator, Russell Howard, Naval Research Laboratory in Washington. This telescope will make 3-D images of the sun's corona, or atmosphere. The experiment will also provide 3-D images of the solar wind and shocks as they approach and pass the spacecraft. This investigation complements instruments on the spacecraft providing direct measurements by imaging the plasma the other instruments sample. Fields Experiment: principal investigator, Stuart Bale, University of California Space Sciences Laboratory in Berkeley, Calif. This investigation will make direct measurements of electric and magnetic fields, radio emissions, and shock waves that course through the sun's atmospheric plasma. The experiment also serves as a giant dust detector, registering voltage signatures when specks of space dust hit the spacecraft's antenna. Integrated Science Investigation of the Sun: principal investigator, David McComas of the Southwest Research Institute in San Antonio. This investigation consists of two instruments that will monitor electrons, protons and ions that are accelerated to high energies in the sun's atmosphere. Heliospheric Origins with Solar Probe Plus: principal investigator, Marco Velli of NASA's Jet Propulsion Laboratory in Pasadena, Calif. Velli is the mission's observatory scientist, responsible for serving as a senior scientist on the science working group. He will provide an independent assessment of scientific performance and act as a community advocate for the mission.
target: Temperatures outside the spacecraft will reach 2,500 degrees Fahrenheit .
  Launch window opens for 20 days starting on July 31, 2018 .