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By NASA
4 min read
Preparations for Next Moonwalk Simulations Underway (and Underwater)
What Would It Take to Say We Found Life?
We call this the podium test. What would it take for you personally to confidently stand up in front of an international audience and make that claim? When you put it in that way, I think for a lot of scientists, the bar is really high.
So of course, there would be obvious things, you know, a very clear signature of technology or a skeleton or something like that. But we think that a lot of the evidence that we might encounter first will be much more subtle. For example, chemical signs of life that have to be detected above a background of abiotic chemistry. And really, what we see might depend a lot on where we look.
On Mars, for example, the long history of exploration there gives us a lot of context for what we might find. But we’re potentially talking about samples that are billions of years old in those cases, and on Earth, those kinds of samples, the evidence of life is often degraded and difficult to detect.
On the ocean worlds of our outer solar system, so places like Jupiter’s moon Europa and Saturn’s moon Enceladus, there’s the tantalizing possibility of extant life, meaning life that’s still alive. But potentially we’re talking about exceedingly small amounts of samples that would have to be analyzed with a relatively limited amount of instrumentation that can be carried from Earth billions of miles away.
And then for exoplanets, these are planets beyond our own solar system. Really, what we’re looking for there are very large magnitude signs of life that can be detectable through a telescope from many light-years away. So changes like the oxygenation of Earth’s atmosphere or changes in surface color.
So any one of those things, if they rose to the suspicion of being evidence of life, would be really heavily scrutinized in a very sort of specific and custom way to that particular observation. But I think there are also some general principles that we can follow. And the first is just: Are we sure we’re seeing what we think we’re seeing? Many of these environments are not very well known to us, and so we need to convince ourselves that we’re actually seeing a clear signal that represents what we think it represents.
Carl Sagan once said, “Life is the hypothesis of last resort,” meaning that we ought to work hard for such a claim to rule out alternative possibilities. So what are those possibilities? One is contamination. The spacecraft and the instruments that we use to look for evidence of life are built in an environment, Earth, that is full of life. And so we need to convince ourselves that what we’re seeing is not evidence of our own life, but evidence of indigenous life.
If that’s the case, we should ask, should life of the type we’re seeing live there? And finally, we need to ask, is there any other way than life to make that thing, any of the possible abiotic processes that we know and even the ones that we don’t know? And as you can imagine, that will be quite a challenge.
Once we have a piece of evidence in hand that we really do think represents evidence of life, now we can begin to develop hypotheses. For example, do we have separate independent lines of evidence that corroborate what we’ve seen and increase our confidence of life?
Ultimately, all of this has to be looked at hard by the entire scientific community, and in that sense, I think the really operative word in our question is we. What does it take to say we found evidence of life? Because really, the answer, I think, depends on the full scientific community scrutinizing and skepticizing this observation to finally say that we scientists, we as a community and we as humanity found life.
[END VIDEO TRANSCRIPT]
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Last Updated Sep 10, 2025 Related Terms
Astrobiology Mars Perseverance (Rover) Science & Research Science Mission Directorate Explore More
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By NASA
NASA/Mike Fincke Eleven International Space Station crew members gather inside the space station’s Unity module for a portrait on Aug. 3, 2025. In the front row, from left are, Kimiya Yui of JAXA (Japan Aerospace Exploration Agency), Zena Cardman of NASA, Oleg Platonov of Roscosmos, and Mike Fincke of NASA. In the second row are, Nichole Ayers of NASA, Sergey Ryzhikov of Roscosmos, and Anne McClain of NASA. In the back are, Takuya Onishi of JAXA, Kirill Peskov of Roscosmos, Jonny Kim of NASA, and Alexey Zubritsky of Roscosmos.
Ayers, McClain, Onishi, and Peskov recently returned to Earth, splashing down in the Pacific Ocean off the coast of California on Aug. 9, 2025.
Keep up with daily activity aboard the orbital laboratory.
Image credit: NASA/Mike Fincke
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By NASA
3 min read
Preparations for Next Moonwalk Simulations Underway (and Underwater)
Ice cover ebbs and flows through the seasons in the Arctic (left) and the Antarctic (right). Overall, ice cover has declined since scientists started tracking it half a century ago. Download this visualization from NASA’s Scientific Visualization Studio: https://svs.gsfc.nasa.gov/5099Trent Schindler/NASA’s Scientific Visualization Studio Winter sea ice cover in the Arctic was the lowest it’s ever been at its annual peak on March 22, 2025, according to NASA and the National Snow and Ice Data Center (NSIDC) at the University of Colorado, Boulder. At 5.53 million square miles (14.33 million square kilometers), the maximum extent fell below the prior low of 5.56 million square miles (14.41 million square kilometers) in 2017.
In the dark and cold of winter, sea ice forms and spreads across Arctic seas. But in recent years, less new ice has been forming, and less multi-year ice has accumulated. This winter continued a downward trend scientists have observed over the past several decades. This year’s peak ice cover was 510,000 square miles (1.32 million square kilometers) below the average levels between 1981 and 2010.
In 2025, summer ice in the Antarctic retreated to 764,000 square miles (1.98 million square kilometers) on March 1, tying for the second lowest minimum extent ever recorded. That’s 30% below the 1.10 million square miles (2.84 million square kilometers) that was typical in the Antarctic prior to 2010. Sea ice extent is defined as the total area of the ocean with at least 15% ice concentration.
The reduction in ice in both polar regions has led to another milestone — the total amount of sea ice on the planet reached an all-time low. Globally, ice coverage in mid-February of this year declined by more than a million square miles (2.5 million square kilometers) from the average before 2010. Altogether, Earth is missing an area of sea ice large enough to cover the entire continental United States east of the Mississippi.
“We’re going to come into this next summer season with less ice to begin with,” said Linette Boisvert, an ice scientist at NASA’s Goddard Space Flight Center in Greenbelt, Maryland. “It doesn’t bode well for the future.”
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Observations since 1978 show that ice cover has declined at both poles, leading to a downward trend in the total ice cover over the entire planet. In February 2025, global ice fell to the smallest area ever recorded. Download this visualization from NASA's Scientific Visualization Studio: https://svs.gsfc.nasa.gov/5521Mark Subbaro/NASA's Scientific Visualization Studio Scientists primarily rely on satellites in the Defense Meteorological Satellite Program, which measure Earth’s radiation in the microwave range. This natural radiation is different for open water and for sea ice — with ice cover standing out brightly in microwave-based satellite images. Microwave scanners can also penetrate through cloud cover, allowing for daily global observations. The DMSP data are augmented with historical sources, including data collected between 1978 and 1985 with the Nimbus-7 satellite that was jointly operated by NASA and the National Oceanic and Atmospheric Administration.
“It’s not yet clear whether the Southern Hemisphere has entered a new norm with perennially low ice or if the Antarctic is in a passing phase that will revert to prior levels in the years to come,” said Walt Meier, an ice scientist with NSIDC.
By James Riordon
NASA’s Earth Science News Team
Media contact: Elizabeth Vlock
NASA Headquarters
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Last Updated Mar 27, 2025 LocationNASA Goddard Space Flight Center Related Terms
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By NASA
Curiosity Navigation Curiosity Home Mission Overview Where is Curiosity? Mission Updates Science Overview Instruments Highlights Exploration Goals News and Features Multimedia Curiosity 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 The Solar System The Sun Mercury Venus Earth The Moon Mars Jupiter Saturn Uranus Neptune Pluto & Dwarf Planets Asteroids, Comets & Meteors The Kuiper Belt The Oort Cloud 4 min read
Sols 4277-4279: Getting Ready To Say Goodbye to the King!
Left navigation camera image from Sol 4255, showing “Milestone Peak” on the left, the subject of an RMI in this plan NASA/JPL-Caltech Earth planning date: Friday, Aug. 16, 2024
It’s time to move on from our “Kings Canyon” drill site, so today’s plan focused on our usual tidy up routine after a drill campaign. First we need to dump out any material in the drill chambers, in an action called “RAGE” – this sounds aggressive but stands for “Rotation to Agitate Granules for Expulsion,” so it’s more of a gentle turning than an angry shaking. This ensures that the drill chambers won’t spill later and we are ready for the next drill campaign – whenever we find a worthy target! Mastcam will document the entire process, and then image the drill bit that was used, making sure it is still in good condition.
At that point, we are free to use the arm instruments again (no turret movements allowed while there is sample in the drill chamber). So our contact science focuses today on the drill tailings, the pile of ground up rock generated by the drill action. That pile has been sitting there for over two weeks, but luckily it’s not too windy right now and the pile remained more or less intact. MAHLI will image the drill hole and the tailings pile on the first afternoon, APXS will integrate on the tailings on the first night and then MAHLI will image the tailings again on the second day. This post-retract image is just to confirm that APXS did not hit the pile of loose drill fines. As APXS Science Planner today, I worked with RPs to pick out the spot we will focus on and to make sure that we are using the correct sequences to ensure safety of the instrument – but it’s always nice to confirm that we didn’t hit the pile!
ChemCam has a suite of activities, from LIBS activities close to the rover, to “passive” (non destructive) activities and RMI images (which can be relatively near field or long distance). LIBS on the bedrock target “Marck Lake” will be used to compared with the nearby Kings Canyon target and assess homogeneity across the drill block, while the passive observation of “Red Slate Mountain” will examine a large light toned block about 10 metres away from the rover. ChemCam will also acquire a long distance RMI of loose blocks and boulders about 85 metres away, looking towards “Milestone Peak” (shown in the accompanying image).
APXS will acquire an overnight “atmospheric” measurement, looking at levels of argon as part of an ongoing campaign. This is paired with ChemCam’s second passive measurement, this time of the sky. We also have monitoring of dust levels, with Mastcam taus of the atmosphere (which atmospheric scientist Alex Innanen talked about here), and a whole host of Navcam dust devil movies, and suprahorizon and zenith movies (which target different parts of the horizon). All of these … and DAN and REMS activities too – our environmental monitoring team is working hard as usual!
ChemCam has spent the last two weeks or so getting LIBS and passive measurements on “Sam Mack Meadow” – an area of darker toned, sometimes broken up rocks just outside of the current workspace. In fact, ChemCam is getting LIBS on two further targets there in this plan: “Horse Creek Spire” and the somewhat nodular “Kearsarge Pinnacles.” Mastcam will image all of the LIBS targets too. There are some interesting textures here that APXS and MAHLI are keen to sample too, so our next drive is more of a bump to get close enough to allow contact science here too. We will still be able to gaze on the King (Canyon) for another while, so I guess it’s not really goodbye just yet!
Written by Catherine O’Connell-Cooper, Planetary Geologist at University of New Brunswick
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Last Updated Aug 19, 2024 Related Terms
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By USH
Stanford Professor Garry Nolanhas been testing the brains of people who say they’ve experienced a UFO encounter as well as he analysis anomalous materials from UFO crashes.
Did the people who claimed that they'd had an encounter, especially the pilots, describe any perceivable decrease in neurological capacity?
Of the 100 or so patients that we looked at, about a quarter of them died from their injuries. The majority of these patients had symptomology that's basically identical to what's now called Havana syndrome.
But Dr. Nolan has also spent the past decade analyzing anomalous materials From UFO crashes
One of the materials from the so called Ubatuba event, a UFO event in Brazil, has extraordinarily altered isotope ratios of magnesium.
What that means is that if you find a metal where the isotope ratios are changed far beyond what is normally found in nature, then that material has likely been engineered, the material is downstream of a process that caused them to be altered. Someone did it. The questions are who… and why?
Speaking to Vice’s Motherboard, Nolan opened up about his work and revealed what sparked his interest in UAP. Learn more at: Vice Motherboard
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