Perched atop a
powerful Delta IV Heavy rocket, NASA's Parker
Solar Probe roared into the
predawn skies over Florida's Cape Canaveral Air Force Station on Aug. 12, 2018.
The durable spacecraft, built and operated at the Johns Hopkins Applied Physics
Laboratory in Laurel, Maryland, has already set speed and solar-distance records,
and continues on its journey to unlock the mysteries of our star. We mark the second
launch anniversary with a look back at the discoveries and milestones reached
during Parker Solar Probe's most recent year in space.
The Parker Solar Probe mission returned unprecedented data
from near the Sun, culminating in several
discoveries published in the journal Nature on Dec. 4, 2019. Among the
findings were new ideas on how the Sun's constant outflow of material, the
solar wind, behaves. Seen near Earth — where it can interact with our planet's
natural magnetic field and cause space weather effects that interfere with
technology — the solar wind appears to be a relatively uniform flow of plasma.
But Parker Solar Probe's observations revealed a complicated, active system not
seen from Earth.
The Solar Wind's First Whispers?
Scientists have studied the solar wind for more than 60
years, but they're still puzzled over some of its behavior. While they know it
comes from the Sun's million-degree upper atmosphere called the corona, the
solar wind, for example, doesn't slow down as it leaves the Sun — it speeds up,
and it has a sort of internal heater that keeps it from cooling as it zips
through space. Yet through the wind's roar, NASA's Parker Solar Probe heard the
small chirps, squeaks and rustles that hint at the origin of this mysterious
and ever-present wind. In January, scientists
got to hear these sounds for the first time.
'We are looking at the young solar wind, being born around
the Sun," said Nour Raouafi, Parker Solar Probe project scientist of the Johns Hopkins Applied Physics Laboratory. "And it's completely different from what we see here near
Records Fall on Fourth Close Pass
At 4:37:42 a.m. EST on Jan. 29, Parker Solar Probe broke
speed and distance records as it completed its fourth close approach of the
Sun. The spacecraft traveled 11.6 million miles from the Sun's surface at
perihelion, reaching a speed of 244,226 miles per hour. Those marks toppled
Parker Solar Probe's own records for closest spacecraft to the Sun — about 15
million miles from the surface — and fastest human-made object, which had been
213,242 miles per hour.
On May 9, Parker Solar Probe began its longest observation
campaign to date. The spacecraft, which had already completed four
progressively closer orbits around the Sun, activated its instruments while
62.5 million miles from the Sun's surface -- some 39 million miles farther out
than during a typical solar encounter. The four instrument suites continued to
collect data through June 28, markedly longer than the mission's standard
The nearly two-month campaign was spurred by Parker Solar
Probe's earlier observations, which revealed significant rotation of the solar
wind and solar wind phenomena occurring much farther from the Sun than
scientists previously thought. The earlier activation of the science
instruments allowed the team additional space to trace the evolution of the
solar wind as it speeds away from the Sun.
On June 9, Parker Solar Probe signaled the success of its
fifth close pass by the Sun, called perihelion, with a radio beacon tone. The
spacecraft completed the fifth perihelion two days prior, flying within 11.6
million miles from the Sun's surface and reaching a top speed of about 244,230
miles per hour, slightly faster than the record it set during its fourth orbit
on Jan. 29.
Eyes on NEOWISE:
Spotting a New Comet
Parker Solar Probe was at the right place at the right time
to capture a unique
view of comet NEOWISE on July 5. Parker Solar Probe's position in space
gave the spacecraft an unmatched view of the comet's twin tails when it was
particularly active just after its closest approach to the Sun, called
The comet was discovered by NASA's Near-Earth Object
Wide-field Infrared Survey Explorer, or NEOWISE, on March 27. Since then, the
comet — officially called comet C/2020 F3 NEOWISE — has been spotted by several
NASA spacecraft, including Parker Solar Probe, NASA's Solar and Terrestrial
Relations Observatory, the ESA/NASA Solar and Heliospheric Observatory and
astronauts aboard the International Space Station.
Outbound from Venus
Coming off its fifth encounter with the Sun — and the
mission's longest observation campaign yet — Parker Solar Probe headed toward
Early on July 11, the spacecraft performed its first
outbound flyby of Venus, passing 518 miles above the surface as it curved
around the planet. Venus gravity assists play an integral role in the mission;
the spacecraft "takes" a bit of orbital energy from the planet on
each pass, which in turn allows Parker Solar Probe to travel ever closer to the
Sun. The mission's previous two Venus flybys sent the spacecraft past the
Sun-facing side of the planet; this was Parker Solar Probe's first flight
around Venus' night side.
Parker Solar Probe witnessed a brief 11-minute solar eclipse
during the maneuver while passing through Venus' shadow. Utilizing powerful
telescopes from Earth, the Apache Point Observatory in New Mexico, Lick Observatory
in California and Keck Observatory in Hawaii searched for Venus' aurora while
Parker Solar Probe flew around planet. Scientists will combine these
ground-based observations with data collected by Parker Solar Probe for
unprecedented look at the interactions between Venus and the solar wind.
The flyby set Parker Solar Probe up for its sixth close pass
by the Sun, slated for Sept. 27. During this perihelion, Parker Solar Probe
will travel even closer to the Sun, setting a record when it passes approximately
8.4 million miles from the solar surface. The spacecraft's seventh perihelion
is slated for Jan. 17, 2021.
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critical national challenges through the innovative application of science and
technology. For more information, visit www.jhuapl.edu.