NASA Solar probe
Encyclopedia
Solar Probe Plus, previously NASA Solar Probe, is a planned robotic spacecraft to probe the outer corona of the Sun. It will approach to within 8.5 solar radii (0.04 astronomical units or 5.9 million kilometers or 3.67 million miles) to the 'surface' (photosphere
) of the Sun. The project was announced as a new mission start in the fiscal 2009 budget year. On May 1, 2008 Johns Hopkins University
Applied Physics Laboratory
announced it will design and build the spacecraft, on a schedule to launch it in 2015.
to cancel the orbital angular momentum of the probe launched from Earth, in order to drop onto a trajectory close to the Sun. The Solar Probe Plus mission design simplifies this trajectory by using multiple gravity assists at Venus, to incrementally decrease the orbital perihelion to achieve multiple passes to approximately 8.5 solar radii, or about 6000000 km (3,728,236.4 mi).
The mission survives the harsh environment near the Sun, where the incident solar intensity is approximately 520 times the intensity at Earth orbit, by the use of a solar shadow-shield. The solar shield, at the front of the spacecraft, is made of reinforced carbon-carbon
composite. The spacecraft systems, and the scientific instruments, are located in the penumbra of the shield. The primary power for the mission will be by use of a dual system of photovoltaic arrays. A primary photovoltaic array, used for the portion of the mission outside of 0.25 AU, is retracted behind the shadow shield during the close approach to the Sun, and a much smaller secondary array powers the spacecraft through closest approach. This secondary array uses pumped-fluid cooling to maintain operating temperature
.
As the probe passes around the Sun, it will achieve a velocity of up to 200 km/s at that time making it the fastest manmade object ever, almost three times faster than the current record holder, Helios II
.
Photosphere
The photosphere of an astronomical object is the region from which externally received light originates. The term itself is derived from Ancient Greek roots, φῶς, φωτός/phos, photos meaning "light" and σφαῖρα/sphaira meaning "sphere", in reference to the fact that it is a spheric surface perceived...
) of the Sun. The project was announced as a new mission start in the fiscal 2009 budget year. On May 1, 2008 Johns Hopkins University
Johns Hopkins University
The Johns Hopkins University, commonly referred to as Johns Hopkins, JHU, or simply Hopkins, is a private research university based in Baltimore, Maryland, United States...
Applied Physics Laboratory
Applied Physics Laboratory
The Johns Hopkins University Applied Physics Laboratory , located in Howard County, Maryland near Laurel and Columbia, is a not-for-profit, university-affiliated research center employing 4,500 people. APL is primarily a defense contractor. It serves as a technical resource for the Department of...
announced it will design and build the spacecraft, on a schedule to launch it in 2015.
Trajectory and mission
Early conceptual designs for the Solar Probe mission used a gravity assist maneuver at JupiterJupiter
Jupiter is the fifth planet from the Sun and the largest planet within the Solar System. It is a gas giant with mass one-thousandth that of the Sun but is two and a half times the mass of all the other planets in our Solar System combined. Jupiter is classified as a gas giant along with Saturn,...
to cancel the orbital angular momentum of the probe launched from Earth, in order to drop onto a trajectory close to the Sun. The Solar Probe Plus mission design simplifies this trajectory by using multiple gravity assists at Venus, to incrementally decrease the orbital perihelion to achieve multiple passes to approximately 8.5 solar radii, or about 6000000 km (3,728,236.4 mi).
The mission survives the harsh environment near the Sun, where the incident solar intensity is approximately 520 times the intensity at Earth orbit, by the use of a solar shadow-shield. The solar shield, at the front of the spacecraft, is made of reinforced carbon-carbon
Reinforced carbon-carbon
Carbon fibre-reinforced carbon is a composite material consisting of carbon fibre reinforcement in a matrix of graphite. It was developed for the nose cones of intercontinental ballistic missiles, and is most widely known as the material for the nose cone and wing leading edges of the Space Shuttle...
composite. The spacecraft systems, and the scientific instruments, are located in the penumbra of the shield. The primary power for the mission will be by use of a dual system of photovoltaic arrays. A primary photovoltaic array, used for the portion of the mission outside of 0.25 AU, is retracted behind the shadow shield during the close approach to the Sun, and a much smaller secondary array powers the spacecraft through closest approach. This secondary array uses pumped-fluid cooling to maintain operating temperature
Operating temperature
An operating temperature is the temperature at which an electrical or mechanical device operates. The device will operate effectively within a specified temperature range which varies based on the device function and application context, and ranges from the minimum operating temperature to the...
.
As the probe passes around the Sun, it will achieve a velocity of up to 200 km/s at that time making it the fastest manmade object ever, almost three times faster than the current record holder, Helios II
Helios probes
Helios-A and Helios-B , were a pair of probes launched into heliocentric orbit for the purpose of studying solar processes. A joint venture of the Federal Republic of Germany and NASA, the probes were launched from the John F. Kennedy Space Center at Cape Canaveral, Florida, on Dec. 10, 1974,...
.
Scientific goals
- Determine the structure and dynamics of the magnetic fieldMagnetic fieldA magnetic field is a mathematical description of the magnetic influence of electric currents and magnetic materials. The magnetic field at any given point is specified by both a direction and a magnitude ; as such it is a vector field.Technically, a magnetic field is a pseudo vector;...
s at the sources of solar windSolar windThe solar wind is a stream of charged particles ejected from the upper atmosphere of the Sun. It mostly consists of electrons and protons with energies usually between 1.5 and 10 keV. The stream of particles varies in temperature and speed over time...
. - Trace the flow of energy that heats the corona and accelerates the solar wind.
- Determine what mechanisms accelerate and transport energetic particles.
- Explore dusty plasmaPlasma (physics)In physics and chemistry, plasma is a state of matter similar to gas in which a certain portion of the particles are ionized. Heating a gas may ionize its molecules or atoms , thus turning it into a plasma, which contains charged particles: positive ions and negative electrons or ions...
near the Sun and its influence on solar wind and energetic particle formation.
External links
- Solar Probe Plus at the Johns Hopkins Applied Physics Laboratory
- Official NASA Solar Probe project homepage
- Solar Probe Plus Mission Engineering Study Report