Achieving the feat that eluded Icarus, on Christmas Eve day NASA’s Parker Solar Probe flew close enough to “touch” the Sun, emerging unscathed on the other side.Breaking its previous record by passing just 3.8 million miles above the Sun’s surface, this “fearless” explorer dared to go where even the gods have been afraid to go.
The Parker Solar Probe passed through the Sun’s outer atmosphere at a mind-boggling 430,000 miles per hour (692,000 kilometers per hour), a speed that was necessary to avoid being burned to a crisp. Even for the heavily heat-shielded Parker probe, pausing to look around and take a few minutes of video could have been disastrous.
The scientists from the Johns Hopkins Applied Physics Laboratory who were monitoring the spacecraft’s travels had to wait (nervously, of course) for two days to see if the NASA probe had survived its encounter with our blazing-hot star. But on December 26 cheers went up all around the tracking room, as the scientists received the beacon signal from the probe confirming that it was just fine.
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Despite its relatively brief stay within the Sun’s intense heat envelope, the Parker Solar Probe was still able to take many different measurements and collect reams of valuable data. What the probe learned has the potential to change our understanding of solar physics, as there are still mysteries to be solved about how exactly our local star functions.
"Flying this close to the Sun is a historic moment in humanity’s first mission to a star,” said Nicky Fox, the head of NASA’s Science Mission Directorate, in a press release from the Goddard Space Flight Center. “By studying the Sun up close, we can better understand its impacts throughout our solar system, including on the technology we use daily on Earth and in space, as well as learn about the workings of stars across the universe to aid in our search for habitable worlds beyond our home planet.”
Boldly Going Where No Probe Has Gone Before
To reach its destination, the Parker Solar Probe needed to cross 90 million miles of space. Originally launched in 2018, the probe made multiple flybys of the planet Venus, which steered it closer and closer to the Sun and ultimately allowed it to reach an optimal orbit following the last such flyby on November 6 of this year.
The nighttime launch of the Parker Solar Probe, from Cape Canaveral, Florida on August 12, 2018. (NASA/Bill Ingalls/Public Domain).
Now that the probe has been steered into the proper orbit, it will continue to pass close by the Sun every three months, hurtling through its atmosphere collecting more and more data each time.
It remains uncertain how long the heat and radiation shielding that protects the Parker Solar Probe will last. But based on the success of the first part of its mission, it is hoped that it will be able to collect and transmit data for a few more years.
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It might seem that a distance of 3.8 million miles from the Sun’s surface is too far to be considered a close approach. But the planet Mercury, which is hellishly hot and impossible to visit, is actually 36 million miles (58 million kilometers) away from the Sun, or more than seven times this distance.
The Sun itself is 864,938 miles (1,392,000 kilometers) in diameter. But its atmosphere, which is known as its corona, stretches out into space for an astonishing five million miles (eight million kilometers) in all directions. Temperatures inside the corona, where the Parker Solar Probe will be passing through repeatedly, can surpass one million degrees Fahrenheit, a number that exceeds the Sun’s surface temperature my many orders of magnitude.
And yet the probe should remain protected, as it is encased in a carbon foam shield that can heat up to 2,600 degrees Fahrenheit while still fully protecting the instrumentation behind it (keeping it at the equivalent of room temperature on Earth in a shaded compartment). The shielding is only expected to heat up to 1,800 degrees Fahrenheit during its flybys, meaning it should remain functional for quite some time.
“It’s monumental to be able to get a spacecraft this close to the Sun,” said John Wirzburger, a Parker Solar Probe mission systems engineer from the Johns Hopkins Applied Physics Laboratory (APL), which designed and built the probe and monitors its operations from their campus in Laurel, Maryland. “This is a challenge the space science community has wanted to tackle since 1958 and had spent decades advancing the technology to make it possible.”
On its passes through the scorching corona, the Parker Solar Probe will take measurements that can help scientists understand how this region heat up so precipitously. The probe will also seek to trace the origin of the solar wind (the constant flow of super-heated particles escaping from the Sun), and discover how energetic particles are accelerated to half the speed of light by such processes.
The Sun and its Solar System are Revealing Their Secrets
Even during its previous not-so-close passes by the Sun, the probe was able to deliver some fascinating and unexpected data. It found, for example, that the corona is wrinkled with spikes and valleys, and is not as smooth as was previously believed. In addition, near the visible surface of the Sun, which is known as the photosphere, the probe identified the origin of strange zig-zag-like structures in the solar wind, which are known as switchbacks.
Illustration of the Sun, with the various parts of the star and its surrounding atmosphere identified. (Kelvinsong/CC BY-SA 3.0).
“The data is so important for the science community because it gives us another vantage point,” said heliophysicist Kelly Korreck, a program scientist at NASA Headquarters who worked on one of the mission’s instruments. “By getting first-hand accounts of what’s happening in the solar atmosphere, the Parker Solar Probe has revolutionized our understanding of the Sun.”
The Parker Solar Probe has made additional discoveries about the inner solar system. It has discovered a phenomenon where coronal mass ejections suck up dust as they sweep across the solar system, and uncovered some intriguing data about the energetic particles that are steadily emitted by the Sun. Flights near Venus have recorded the planet’s natural radio emissions, and also photographed its orbital dust ring.
The probe will be passing close to the Sun again twice during the first six months of the new year, on March 22 and June 19. The analysis of the newly collected date from the Christmas Eve flyby will begin soon, and it is expected to reveal at least a few surprises.
Top image: An artist’s conception of the Parker Solar Probe as it hurtles through the Sun’s atmosphere.
Source: Steve Gribben/NASA/APL/Public Domain.
By Nathan Falde
