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By Space Force
128 Air Force Reserve Professionals who will transfer into the Space Force in a full-time capacity.
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By NASA
Explore This Section Perseverance Home Mission Overview Rover Components Mars Rock Samples Where is Perseverance? Ingenuity Mars Helicopter Mission Updates Science Overview Objectives Instruments Highlights Exploration Goals News and Features Multimedia Perseverance Raw Images Images Videos Audio More Resources Mars Missions Mars Sample Return Mars Perseverance Rover Mars Curiosity Rover MAVEN Mars Reconnaissance Orbiter Mars Odyssey More Mars Missions Mars Home 3 min read
Visiting Mars on the Way to the Outer Solar System
Written by Roger Wiens, Principal Investigator, SuperCam instrument / Co-Investigator, SHERLOC instrument at Purdue University
A portion of the “Sally’s Cove” outcrop where the Perseverance rover has been exploring. The radiating lines in the rock on the left of the image may indicate that it is a shatter cone, showing the effects of the shock wave from a nearby large impact. The image was taken by Mastcam-Z’s left camera on March 21, 2025 (Sol 1452, or Martian day 1,452 of the Mars 2020 mission) at the local mean solar time of 12:13:44. Mastcam-Z is a pair of cameras located high on the rover’s mast. This image was voted by the public as “Image of the week.” NASA/JPL-Caltech/ASU Recently Mars has had a few Earthly visitors. On March 1, NASA’s Europa Clipper flew within 550 miles (884 kilometers) of the Red Planet’s surface on its way out to Jupiter. On March 12, the European Space Agency’s Hera spacecraft flew within about 3,100 miles (5,000 kilometers) of Mars, and only 300 kilometers from its moon, Deimos. Hera is on its way to study the binary asteroid Didymos and its moon Dimorphos. Next year, in May 2026, NASA’s Psyche mission is scheduled to buzz the Red Planet on its way to the metal-rich asteroid 16 Psyche, coming within a few thousand kilometers.
Why all these visits to Mars? You might at first think that they’re using Mars as an object of opportunity for their cameras, and you would be partially right. But Mars has more to give these missions than that. The main reason for these flybys is the extra speed that Mars’ velocity around the Sun can give them. The idea that visiting a planet can speed up a spacecraft is not all that obvious, because the same gravity that attracts the spacecraft on its way towards the planet will exert a backwards force as the spacecraft leaves the planet.
The key is in the direction that it approaches and leaves the planet. If the spacecraft leaves Mars heading in the direction that Mars is traveling around the Sun, it will gain speed in that direction, slingshotting it farther into the outer solar system. A spacecraft can typically gain several percent of its speed by performing such a slingshot flyby. The closer it gets to the planet, the bigger the effect. However, no mission wants to be slowed by the upper atmosphere, so several hundred kilometers is the closest that a mission should go. And the proximity to the planet is also affected by the exact direction the spacecraft needs to go when it leaves Mars.
Clipper’s Mars flyby was a slight exception, slowing down the craft — by about 1.2 miles per second (2 kilometers per second) — to steer it toward Earth for a second gravity assist in December 2026. That will push the spacecraft the rest of the way to Jupiter, for its 2030 arrival.
While observing Mars is not the main reason for their visits, many of the visiting spacecraft take the opportunity to use their cameras either to perform calibrations or to study the Red Planet and its moons.
During Clipper’s flyby over sols 1431-1432, Mastcam-Z was directed to watch the skies for signs of the interplanetary visitor. Clipper’s relatively large solar panels could have reflected enough sunlight for it to be seen in the Mars night sky, much as we can see satellites overhead from Earth. Unfortunately, the spacecraft entered the shadow of Mars just before it came into potential view above the horizon from Perseverance’s vantage point, so the sighting did not happen. But it was worth a try.
Meanwhile, back on the ground, Perseverance is performing something of a cliff-hanger. “Sally’s Cove” is a relatively steep rock outcrop in the outer portion of Jezero crater’s rim just north of “Broom Hill.” Perseverance made an approach during March 19-23, and has been exploring some dark-colored rocks along this outcrop, leaving the spherules behind for the moment. Who knows what Perseverance will find next?
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Last Updated Mar 28, 2025 Related Terms
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6 Min Read NASA’s Webb Captures Neptune’s Auroras For First Time
At the left, an enhanced-color image of Neptune from NASA’s Hubble Space Telescope. At the right, that image is combined with data from NASA’s James Webb Space Telescope. Credits:
NASA, ESA, CSA, STScI, Heidi Hammel (AURA), Henrik Melin (Northumbria University), Leigh Fletcher (University of Leicester), Stefanie Milam (NASA-GSFC) Long-sought auroral glow finally emerges under Webb’s powerful gaze
For the first time, NASA’s James Webb Space Telescope has captured bright auroral activity on Neptune. Auroras occur when energetic particles, often originating from the Sun, become trapped in a planet’s magnetic field and eventually strike the upper atmosphere. The energy released during these collisions creates the signature glow.
In the past, astronomers have seen tantalizing hints of auroral activity on Neptune, for example, in the flyby of NASA’s Voyager 2 in 1989. However, imaging and confirming the auroras on Neptune has long evaded astronomers despite successful detections on Jupiter, Saturn, and Uranus. Neptune was the missing piece of the puzzle when it came to detecting auroras on the giant planets of our solar system.
“Turns out, actually imaging the auroral activity on Neptune was only possible with Webb’s near-infrared sensitivity,” said lead author Henrik Melin of Northumbria University, who conducted the research while at the University of Leicester. “It was so stunning to not just see the auroras, but the detail and clarity of the signature really shocked me.”
The data was obtained in June 2023 using Webb’s Near-Infrared Spectrograph. In addition to the image of the planet, astronomers obtained a spectrum to characterize the composition and measure the temperature of the planet’s upper atmosphere (the ionosphere). For the first time, they found an extremely prominent emission line signifying the presence of the trihydrogen cation (H3+), which can be created in auroras. In the Webb images of Neptune, the glowing aurora appears as splotches represented in cyan.
Image A:
Neptune’s Auroras – Hubble and Webb
At the left, an enhanced-color image of Neptune from NASA’s Hubble Space Telescope. At the right, that image is combined with data from NASA’s James Webb Space Telescope. The cyan splotches, which represent auroral activity, and white clouds, are data from Webb’s Near-Infrared Spectrograph (NIRSpec), overlayed on top of the full image of the planet from Hubble’s Wide Field Camera 3. NASA, ESA, CSA, STScI, Heidi Hammel (AURA), Henrik Melin (Northumbria University), Leigh Fletcher (University of Leicester), Stefanie Milam (NASA-GSFC) “H3+ has a been a clear signifier on all the gas giants — Jupiter, Saturn, and Uranus — of auroral activity, and we expected to see the same on Neptune as we investigated the planet over the years with the best ground-based facilities available,” explained Heidi Hammel of the Association of Universities for Research in Astronomy, Webb interdisciplinary scientist and leader of the Guaranteed Time Observation program for the Solar System in which the data were obtained. “Only with a machine like Webb have we finally gotten that confirmation.”
The auroral activity seen on Neptune is also noticeably different from what we are accustomed to seeing here on Earth, or even Jupiter or Saturn. Instead of being confined to the planet’s northern and southern poles, Neptune’s auroras are located at the planet’s geographic mid-latitudes — think where South America is located on Earth.
This is due to the strange nature of Neptune’s magnetic field, originally discovered by Voyager 2 in 1989 which is tilted by 47 degrees from the planet’s rotation axis. Since auroral activity is based where the magnetic fields converge into the planet’s atmosphere, Neptune’s auroras are far from its rotational poles.
The ground-breaking detection of Neptune’s auroras will help us understand how Neptune’s magnetic field interacts with particles that stream out from the Sun to the distant reaches of our solar system, a totally new window in ice giant atmospheric science.
From the Webb observations, the team also measured the temperature of the top of Neptune’s atmosphere for the first time since Voyager 2’s flyby. The results hint at why Neptune’s auroras remained hidden from astronomers for so long.
“I was astonished — Neptune’s upper atmosphere has cooled by several hundreds of degrees,” Melin said. “In fact, the temperature in 2023 was just over half of that in 1989.”
Through the years, astronomers have predicted the intensity of Neptune’s auroras based on the temperature recorded by Voyager 2. A substantially colder temperature would result in much fainter auroras. This cold temperature is likely the reason that Neptune’s auroras have remained undetected for so long. The dramatic cooling also suggests that this region of the atmosphere can change greatly even though the planet sits over 30 times farther from the Sun compared to Earth.
Equipped with these new findings, astronomers now hope to study Neptune with Webb over a full solar cycle, an 11-year period of activity driven by the Sun’s magnetic field. Results could provide insights into the origin of Neptune’s bizarre magnetic field, and even explain why it’s so tilted.
“As we look ahead and dream of future missions to Uranus and Neptune, we now know how important it will be to have instruments tuned to the wavelengths of infrared light to continue to study the auroras,” added Leigh Fletcher of Leicester University, co-author on the paper. “This observatory has finally opened the window onto this last, previously hidden ionosphere of the giant planets.”
These observations, led by Fletcher, were taken as part of Hammel’s Guaranteed Time Observation program 1249. The team’s results have been published in Nature Astronomy.
The James Webb Space Telescope is the world’s premier space science observatory. Webb is solving mysteries in our solar system, looking beyond to distant worlds around other stars, and probing the mysterious structures and origins of our universe and our place in it. Webb is an international program led by NASA with its partners, ESA (European Space Agency) and CSA (Canadian Space Agency).
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Media Contacts
Laura Betz – laura.e.betz@nasa.gov
NASA’s Goddard Space Flight Center, Greenbelt, Md.
Hannah Braun- hbraun@stsci.edu
Space Telescope Science Institute, Baltimore, Maryland
Christine Pulliam – cpulliam@stsci.edu
Space Telescope Science Institute, Baltimore, Md.
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Henrik Melin (Northumbria University)
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Last Updated Mar 25, 2025 Editor Stephen Sabia Contact Laura Betz laura.e.betz@nasa.gov Related Terms
James Webb Space Telescope (JWST) Astrophysics Goddard Space Flight Center Neptune Planetary Science Planets Science & Research The Solar System View the full article
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