TheWide-Field Imager for Solar Probe (WISPR) is an imaging instrument of theParker Solar Probe mission to theSun, launched in August 2018.[1] Imaging targets include visible light images of thecorona,solar wind, shocks, solar ejecta, etc.[1] Development of WISPR was led by theU.S. Naval Research Laboratory.[2] TheParker Solar Probe with WISPR on board was launched by aDelta IV Heavy on 12 August 2018 fromCape Canaveral, Florida.[3] WISPR is intended to take advantage of the spacecraft's proximity to the Sun by takingcoronagraph-style images of the solar corona and features like coronal streamers, plumes, andmass ejections.[4] One of the goals is to better understand the structure of the solar corona near the Sun.[4]
WISPR is designed to study theelectron density and velocity structure of the corona.[5] The instrument field of view is planned to extend from 13 to 108 degrees away from the Sun, and does not directly image the Sun; the area of interest is a very wide field extending away from the Sun.[1]
WISPR includes two separate telescopes, each with aradiation-hardenedCMOS imager with resolution of 2,048×1,920 pixels.[6] The CMOS sensors are anactive pixel sensor type of detector.[7] The two telescopes are designated WISPR-Inner (WISPR-I) and WISPR-Outer (WISPR-O), with WISPR-I observing atangles 13°–53° away from the Sun and WISPR-O viewing elongations of 50°–108°.[8] Both telescopes observe at both visible andnear-infrared wavelengths,[9] withbandpass filters of 490–740 nm and 475–725 nm on WISPR-I and WISPR-O, respectively.[10]
The WISPRfirst light image was published in September 2018.[11] In December, a view of the corona including a coronal streamer was released.[12]
In November 2018, a video of WIPSR recording solar wind during the spacecraft's first close pass to the Sun was released.[13] One project scientist noted, "The data we’re seeing from Parker Solar Probe’s instruments is showing us details about solar structures and processes that we have never seen before."[13]
Thestray light and baffle for WISPR was modeled during development of the instrument.[14] Two noted cases where stray material caused issue with space imaging includes the Infrared Telescope (IRT) flown on the Space ShuttleSpacelab-2 mission, in which a piece ofmylar insulation broke loose and floated into the line-of-sight of the telescope corrupting data.[15] This was on theSTS-51-F in the year 1985.[15] Another case was in the 2010s on the Gaia spacecraft for which some stray light was identified coming from fibers of the sunshield, protruding beyond the edges of the shield.[16]
WISPR first light image. The right portion of the image is from WISPR's inner telescope, which is a 40-degree field of view and begins 58.5 degrees from the Sun's center. The left portion is from the outer telescope, which is a 58-degree field of view and ends about 160 degrees from the Sun.[11]
The view from the probe's WISPR instrument on Sept. 25, 2018, shows Earth, the bright sphere near the middle of the right-hand panel. The elongated mark toward the bottom of the panel is a lens reflection from the WISPR instrument[17]
Photo from the WISPR shows a coronal streamer, seen over the east limb of the Sun on Nov. 8, 2018, at 1:12 a.m. EST. The fine structure of the streamer is very clear, with at least two rays visible. Parker Solar Probe was about 16.9 million miles from the Sun's surface when this image was taken. The bright object near the center of the image is Mercury, and the dark spots are a result of background correction.[12]
When Parker Solar Probe was making its closest approach to the Sun on June 7, 2020, WISPR captured the planets Mercury, Venus, Earth, Mars, Jupiter and Saturn in its field of view[18]
Photo taken by the probe during its secondVenus flyby, July 2020
As Parker Solar Probe flew by Venus on its fourth flyby, its WISPR instrument captured these images, showing the nightside surface of the planet[19]
As the probe passed through the Sun's corona in early 2021, it flew by structures calledcoronal streamers
^Wood, Brian E.; Hess, Phillip; Lustig‐Yaeger, Jacob; Gallagher, Brendan; Korwan, Daniel; Rich, Nathan; Stenborg, Guillermo; Thernisien, Arnaud; Qadri, Syed N.; Santiago, Freddie; Peralta, Javier; Arney, Giada N.; Izenberg, Noam R.; Vourlidas, Angelos; Linton, Mark G.; Howard, Russell A.; Raouafi, Nour E. (16 February 2022)."Parker Solar Probe Imaging of the Night Side of Venus".Geophysical Research Letters.49 (3).doi:10.1029/2021GL096302.PMC9286398.