In A First, NASA Captures Visible Light Images Of Venus From Space | WATCH It Glowing Like 'Iron'
NASA's Parker Solar Probe, the spacecraft which "touched the Sun" last year, has captured its first visible light images of the surface of Venus from space.
New Delhi: NASA's Parker Solar Probe, the spacecraft which "touched the Sun" last year, has captured its first visible light images of the surface of Venus from space.
Venus' surface is usually shrouded from sight, as it is smothered in thick clouds. The Parker Solar Probe, also called Parker, in the spacecraft's two recent flybys of Venus, used the Wide-Field Imager for Parker Solar Probe, or WISPR, to image the entire nightside in wavelengths of the visible spectrum, NASA said on its website. WISPR are the cameras pointed at the nightside of Venus as the spacecraft flew by the planet in 2020 and 2021.
Visible light is what the human eye can see, and extends to the near-infrared spectrum.
The images captured by Parker have been combined into a video. They reveal a faint glow from the surface that shows distinctive features like continental regions, plains, and plateaus. In the atmosphere of Venus, a luminescent halo of oxygen can be seen surrounding the bright planet.
The findings of the study were published on Wednesday, February 9, in the journal, Geophysical Research Letters.
"We're thrilled with the science insights Parker Solar Probe has provided thus far," Nicola Fox, division director for the Heliophysics Division at NASA Headquarters, was quoted as saying in NASA statement.
She said that Parker continues to outperform our expectations, and NASA is excited that these novel observations taken during the gravity assist maneuver can help advance Venus research in unexpected ways.
Venus is often called Earth's twin, and such images can help scientists learn more about the planet's surface geology, what minerals might be present there, and the planet's evolution, according to NASA.
Since Earth and Venus have certain similarities, the information about the latter can help scientists understand why Venus became inhospitable, and Earth became an oasis.
Quoting Brian Wood, the lead author on the new study and physicist at the Naval Research Laboratory in Washington, DC, the statement said that Venus is the third brightest thing in the sky, but until recently, "we have not had much information on what the surface looked like because our view of it is blocked by a thick atmosphere.
"Now, we finally are seeing the surface in visible wavelengths for the first time from space," he further said.
Venus 'Glowing Like An Iron From The Forge'
Most of the visible light coming from Venus' surface is obstructed by clouds. However, the very longest visible wavelengths, which border the near-infrared wavelengths, make it through, according to NASA.
This red light, on the day side, gets lost amid the bright sunshine reflected off Venus' cloud tops.
The WISPR cameras, in the darkness of the night, were able to pick the faint glow caused by the incredible heat emanating from the surface of Venus.
Wood said that the surface of Venus, even on the nightside, is about 860 degrees. He added that it is so hot the rocky surface of Venus is visibly glowing, like a "piece of iron pulled from a forge."
WISPR picked up a range of wavelengths from 470 nanometres to 800 nanometres, as it passed by Venus.
Near-infrared wavelengths cannot be discerned by the human eye, but can be sensed as heat. Some of the light picked up by WISPR belongs to the near-infrared spectrum.
Some of the light is in the visible range, between 380 nanometres and about 750 nanometres, according to NASA.
When & How Did WISPR Take The Images?
The Wide-Field Imager for Parker Solar Probe (WISPR) imager on board the Parker Solar Probe observed the night side of Venus, during two recent gravity-assist flybys. WISPR unexpectedly penetrated the thick atmosphere of Venus, the study said, detecting thermal emission from the surface. This makes it the first detection of the Venusian surface by an optical telescope, yeh study said.
The high temperature of the Venusian surface makes the thermal emission detectable. Even on the night side, the surface temperature reaches an estimated 735 Kelvin.
A bright rim of emission at the limb of Venus is shown by the WISPR images. In astronomy, the limb of an object such as the Sun, a planet, or a satellite is the object's apparent edge as seen against the dark sky background.
The bright rim of emission at the limb is associated with night glow emission from molecular oxygen, which is somewhat analogous to auroral emission observed at Earth, the study said.
Parker captured the first WISPR images of Venus in July 2020. This was when the spacecraft embarked on its third flyby, a technique used to bend its orbit to the Sun.
The main purpose of WISPR is to see faint features in the solar atmosphere and wind. Some scientists thought WISPR may be used to image the cloud tops veiling Venus as Parker.
Quoting WISPR project scientist Angelos Vourlidas, the NASA statement said that the objective was to measure the speed of the clouds.
WISPR, instead of just seeing clouds, also saw through to the surface of Venus. During the fourth pass of Parker in February 2021, the scientists turned on the cameras again. The spacecraft's orbit, during the 2021 flyby, lined up perfectly for WISPR to image Venus' nightside in entirety.
Wood said: "The images and video just blew me away".
Scientists saw light and dark surface features. This is the first time visible light from the Venusian surface has been captured from space.
Wood said that it is thrilling to be able to see something that has never been seen before, according to a video released by NASA. The emission seen from Venus is thermal emission. Even on the night side, the surface of Venus is so hot that it is glowing faintly at very red wavelengths, he said.
What Do The WISPR Images Reveal?
The WISPR images reveal features on the Venusian surface, such as the continental region Aphrodite Terra, the Tellus Regio plateau, and the Aino Planitia plains.
Aphrodite Terra is the largest highland region on Venus.
The landforms show up as dark patches amidst the brighter lowlands because higher altitude regions are about 85 degrees Fahrenheit cooler than lower areas.
In previous radar images, such as those taken by Magellan, these features can be seen. NASA's Magellan spacecraft was a robotic space probe launched in 1989 to map the surface of Venus by using synthetic-aperture radar.
In the images, light areas are hotter and dark areas are cooler, according to NASA.
Giada Arney, Research Space Scientist at NASA's Goddard Space Flight Center, said these WISPR images are really exciting because they provide a new window into the lower atmosphere and surface region of Venus, where these extreme conditions exist.
How Will The New Images Benefit Scientists?
In order to see how temperatures change with altitude, scientists compared the WISPR images to topographical maps created with radar.
Higher elevations tend to be cooler, and lower regions tend to be hotter. Scientists can also see other heat variations with the help of the images.
Arney said that another really interesting thing one can look for is potentially mineralogical differences, according to the video. Different rocks, different minerals emit different levels of heat, she said.
Understanding the composition of the surface could teach scientists about the planet's evolution.
Venus is inhospitable to life with extreme temperatures, toxic clouds, and a crushing atmosphere. But the planet may have had a different past, according to NASA.
According to Arney, there are chemical fingerprints in Venus' atmosphere and on its surface suggesting that Venus might have been habitable in the past.
The Soviet Union's General program is the only other mission to capture visible light images of the surface of Venus. The spacecraft took the images when it landed on the planet.
Since then, Venus has been studied with infrared and radar instruments that can peer through the dense atmosphere.
"The WISPR images extend our observations to red visible light at the edge of what the human eye can see," NASA says.
In 2024, Parker will have a final chance to image Venus.
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