SWEAP (Solar Wind Electrons Alphas and Protons) is an instrument on the unmanned space probe to the Sun, the

Parker Solar Probe The Parker Solar Probe (PSP; previously Solar Probe, Solar Probe Plus or Solar Probe+) is a NASA space probe launched in 2018 with the mission of making observations of the outer corona of the Sun. It will approach to within 9.86 solar radii (6 ...

. The spacecraft with SWEAP on board was launched by a

Delta IV Heavy The Delta IV Heavy (Delta 9250H) is an Evolved Expendable Launch Vehicle, expendable heavy-lift launch vehicle, the largest type of the Delta IV family. It is the world's third highest-capacity launch vehicle in operation, behind NASA's Space L ...

on 12 August 2018 from

Cape Canaveral , image = cape canaveral.jpg , image_size = 300 , caption = View of Cape Canaveral from space in 1991 , map = Florida#USA , map_width = 300 , type =Cape , map_caption = Location in Florida , location ...

, Florida. SWEAP includes two types of instruments, the Solar Probe Cup (SPC) and Solar Probe Analyzers (SPAN). SWEAP has four sensors overall, and is designed to take measurements of the

Solar wind The solar wind is a stream of charged particles released from the upper atmosphere of the Sun, called the corona. This plasma mostly consists of electrons, protons and alpha particles with kinetic energy between . The composition of the sola ...

including

electron The electron ( or ) is a subatomic particle with a negative one elementary electric charge. Electrons belong to the first generation of the lepton particle family, and are generally thought to be elementary particles because they have no kn ...

s and ions of hydrogen (

proton A proton is a stable subatomic particle, symbol , H+, or 1H+ with a positive electric charge of +1 ''e'' elementary charge. Its mass is slightly less than that of a neutron and 1,836 times the mass of an electron (the proton–electron mass ...

s) and helium (these are the main components of the

and coronal plasma).

Design

SWEAP consists of the Solar Probe Cup (SPC), a

faraday cup A Faraday cup is a metal (conductive) cup designed to catch charged particles in vacuum. The resulting current can be measured and used to determine the number of ions or electrons hitting the cup. The Faraday cup was named after Michael Faraday w ...

which faces the Sun and is designed to measure

s and

ion An ion () is an atom or molecule with a net electrical charge. The charge of an electron is considered to be negative by convention and this charge is equal and opposite to the charge of a proton, which is considered to be positive by conve ...

s in the space environment near the Sun; the Solar Probe Analyzers (SPAN-A and SPAN-B); and the SWEAP electronics module (SWEM). The Solar Probe Cup is a Sun facing instrument directly exposed to the Sun, and had to be designed to handle the high temperature conditions at 9-10 Solar radii from the Sun, that are planned for the mission. In operation it peeks out from the probes Sun shield, and is made entirely of

refractory In materials science, a refractory material or refractory is a material that is resistant to decomposition by heat, pressure, or chemical attack, and retains strength and form at high temperatures. Refractories are polycrystalline, polyphase, ...

materials to endure these conditions. The hottest portion, the grid in front of the cup, can be heated to and is made of

tungsten Tungsten, or wolfram, is a chemical element with the symbol W and atomic number 74. Tungsten is a rare metal found naturally on Earth almost exclusively as compounds with other elements. It was identified as a new element in 1781 and first isolat ...

. The wiring connecting to the electronics is made of

niobium Niobium is a chemical element with chemical symbol Nb (formerly columbium, Cb) and atomic number 41. It is a light grey, crystalline, and ductile transition metal. Pure niobium has a Mohs hardness rating similar to pure titanium, and it has sim ...

with

sapphire Sapphire is a precious gemstone, a variety of the mineral corundum, consisting of aluminium oxide () with trace amounts of elements such as iron, titanium, chromium, vanadium, or magnesium. The name sapphire is derived via the Latin "sapphir ...

insulators. SPAN-A and B are behind the heat shield, oriented forward ("ram side") and backward along the spacecraft's orbit, and take electron and ion measurements overs a wide

field of view The field of view (FoV) is the extent of the observable world that is seen at any given moment. In the case of optical instruments or sensors it is a solid angle through which a detector is sensitive to electromagnetic radiation. Humans a ...

. SPAN-A measure ions and electrons and SPAN-B measures electrons. Summary: *Solar Probe Cup (SPC): Outside solar shield directly exposed to the Sun *Solar Probe Analyzers (SPAN) **SPAN-Ai: ion electrostatic analyzer (ESA) on the ram side **SPAN-Ae: electron electrostatic analyzer on the ram side **SPAN-B: electron electrostatic analyzer on the anti-ram side *SWEAP Electronics Module (SWEM)

Operations

By September 2018, SWEAP had been turned on and first light data was returned.

Location

References

{{Psp Parker Solar Probe Spacecraft instruments

Design

Operations

Location

See also

References