A new spacecraft is journeying to the Sun to snap the first pictures of
the Sun’s north and south poles.
Solar Orbiter, a
collaboration between the European Space Agency, or ESA, and NASA, will have
its first opportunity to launch from Cape Canaveral on Feb. 7, 2020, at
11:15 p.m. EST. Launching on a United Launch Alliance Atlas V rocket, the
spacecraft will use Venus’s and Earth’s gravity to swing itself out of the
ecliptic plane — the swath of space, roughly aligned with the
Sun’s equator, where all planets orbit. From there, Solar
Orbiter’s bird’s eye view will give it the first-ever look at the Sun’s poles.
“Up until Solar
Orbiter, all solar imaging instruments have been within the ecliptic plane or
very close to it,” said Russell Howard, space scientist at the Naval Research
Lab in Washington, D.C. and principal investigator for one of Solar Orbiter’s
ten instruments. “Now, we’ll be able to look down on the Sun from above.”
“It will be
terra incognita,” said Daniel Müller, ESA project scientist for the mission at
the European Space Research and Technology Centre in the Netherlands. “This is
really exploratory science.”
The Sun plays a
central role in shaping space around us. Its massive magnetic field stretches
far beyond Pluto, paving a superhighway for charged solar particles known as
the solar wind. When bursts of solar wind hit Earth, they can spark space
weather storms that interfere with our GPS and communications satellites — at
their worst, they can even threaten astronauts.
To prepare for
arriving solar storms, scientists monitor the Sun’s magnetic field. But their
techniques work best with a straight-on view; the steeper the viewing angle,
the noisier the data. The sidelong glimpse we get of the Sun’s poles from
within the ecliptic plane leaves major gaps in the data.
“The poles are
particularly important for us to be able to model more accurately,” said Holly
Gilbert, NASA project scientist for the mission at NASA’s Goddard Space Flight
Center in Greenbelt, Maryland. “For forecasting space weather events, we need a
pretty accurate model of the global magnetic field of the Sun.”
The Sun’s poles
may also explain centuries-old observations. In 1843, German astronomer Samuel
Heinrich Schwabe discovered that the number of sunspots — dark blotches on
the Sun’s surface marking strong magnetic fields — waxes and wanes in a
repeating pattern. Today, we know it as the approximately-11-year solar cycle
in which the Sun transitions between solar maximum, when sunspots proliferate
and the Sun is active and turbulent, and solar minimum, when they’re
fewer and it’s calmer. “But we don’t understand why it’s 11 years, or why
some solar maximums are stronger than others,” Gilbert said. Observing the
changing magnetic fields of the poles could offer an answer.
The only prior
spacecraft to fly over the Sun’s poles was also a joint ESA/NASA venture.
Launched in 1990, the Ulysses spacecraft made three passes around our star
before it was decommissioned in 2009. But Ulysses never got closer than
Earth-distance to the Sun, and only carried what’s known as in
situ instruments — like the sense of touch, they measure the space
environment immediately around the spacecraft. Solar Orbiter, on the other
hand, will pass inside the orbit of Mercury carrying four in situ instruments
and six remote-sensing imagers, which see the Sun from afar. “We are going
to be able to map what we ‘touch’ with the in situ instruments and what we
‘see’ with remote sensing,” said Teresa Nieves-Chinchilla, NASA deputy project
scientist for the mission.
After years of
technology development, it will be the closest any Sun-facing cameras have ever
gotten to the Sun. “You can’t really get much closer than Solar Orbiter is
going and still look at the Sun,” Müller said.
Over the
mission’s seven year lifetime, Solar Orbiter will reach an inclination of 24
degrees above the Sun’s equator, increasing to 33 degrees with an additional
three years of extended mission operations. At closest approach the spacecraft
will pass within 26 million miles of the Sun.
To beat the
heat, Solar Orbiter has a custom-designed titanium heat shield with a calcium
phosphate coating that withstands temperatures over 900 degrees Fahrenheit —
thirteen times the solar heating faced by spacecraft in Earth orbit. Five of
the remote-sensing instruments look at the Sun through peepholes in that heat
shield; one observes the solar wind out to the side.
Solar Orbiter
will be NASA’s second major mission to the inner solar system in recent years,
following on August 2018’s launch of Parker Solar Probe. Parker has completed
four close solar passes and will fly within four million miles of the Sun at
closest approach.
The two
spacecraft will work together: As Parker samples solar particles up close,
Solar Orbiter will capture imagery from farther away, contextualizing the
observations. The two spacecraft will also occasionally align to measure the
same magnetic field lines or streams of solar wind at different times.
“We are learning
a lot with Parker, and adding Solar Orbiter to the equation will only bring
even more knowledge,” said Nieves-Chinchilla.
Source: https://myfusimotors.com/2020/02/01/new-mission-will-take-1st-peek-at-suns-poles/
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