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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
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By European Space Agency
Following the announcement of the upcoming launch of LEO-PNT’s first satellites, ESA has now unveiled the name of the mission. Celeste, as it has been officially designated, will test the potential of a new, low Earth orbit layer of satellites to enhance Galileo’s resilience and complement its capabilities.
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By European Space Agency
The second of the Meteosat Third Generation Imagers, MTG-I2, has passed some important milestones in the cleanroom facilities at Thales Alenia Space in Cannes, southern France.
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By NASA
NASA science and American industry have worked hand-in-hand for more than 60 years, transforming novel technologies created with NASA research into commercial products like cochlear implants, memory-foam mattresses, and more. Now, a NASA-funded device for probing the interior of storm systems has been made a key component of commercial weather satellites.
The novel atmospheric sounder was originally developed for NASA’s TROPICS (short for Time-Resolved Observations of Precipitation structure and storm Intensity with a Constellation of SmallSats), which launched in 2023. Boston-based weather technology company Tomorrow.io integrated the same instrument design into some of its satellites.
NASA’s TROPICS instrument. TROPICS pioneered a novel, compact atmospheric sound now flying aboard a fleet of commercial small satellites created by the weather technology company Tomorrow.io.Credit: Blue Canyon Technologies Atmospheric sounders allow researchers to gather data describing humidity, temperature, and wind speed — important factors for weather forecasting and atmospheric analysis. From low-Earth orbit, these devices help make air travel safer, shipping more efficient, and severe weather warnings more reliable.
Novel tools for Observing Storm Systems
In the early 2000s, meteorologists and atmospheric chemists were eager to find a new science tool that could peer deep inside storm systems and do so multiple times a day. At the same time, CubeSat constellations (groupings of satellites each no larger than a shoebox) were emerging as promising, low-cost platforms for increasing the frequency with which individual sensors could pass over fast-changing storms, which improves the accuracy of weather models.
The challenge was to create an instrument small enough to fit aboard a satellite the size of a toaster, yet powerful enough to observe the innermost mechanisms of storm development. Preparing these technologies required years of careful development that was primarily supported by NASA’s Earth Science Division.
William Blackwell and his team at MIT Lincoln Laboratory in Cambridge, Massachusetts, accepted this challenge and set out to miniaturize vital components of atmospheric sounders. “These were instruments the size of a washing machine, flying on platforms the size of a school bus,” said Blackwell, the principal investigator for TROPICS. “How in the world could we shrink them down to the size of a coffee mug?”
With a 2010 award from NASA’s Earth Science Technology Office (ESTO), Blackwell’s team created an ultra-compact microwave receiver, a component that can sense the microwave radiation within the interior of storms.
The Lincoln Lab receiver weighed about a pound and took up less space than a hockey puck. This innovation paved the way for a complete atmospheric sounder instrument small enough to fly aboard a CubeSat. “The hardest part was figuring out how to make a compact back-end to this radiometer,” Blackwell said. “So without ESTO, this would not have happened. That initial grant was critical.”
In 2023, that atmospheric sounder was sent into space aboard four TROPICS CubeSats, which have been collecting torrents of data on the interior of severe storms around the world.
Transition to Industry
By the time TROPICS launched, Tomorrow.io developers knew they wanted Blackwell’s microwave receiver technology aboard their own fleet of commercial weather satellites. “We looked at two or three different options, and TROPICS was the most capable instrument of those we looked at,” said Joe Munchak, a senior atmospheric data scientist at Tomorrow.io.
In 2022, the company worked with Blackwell to adapt his team’s design into a CubeSat platform about twice the size of the one used for TROPICS. A bigger platform, Blackwell explained, meant they could bolster the sensor’s capabilities.
“When we first started conceptualizing this, the 3-unit CubeSat was the only game in town. Now we’re using a 6-unit CubeSat, so we have room for onboard calibration,” which improves the accuracy and reliability of gathered data, Blackwell said.
Tomorrow.io’s first atmospheric sounders, Tomorrow-S1 and Tomorrow-S2, launched in 2024. By the end of 2025, the company plans to have a full constellation of atmospheric sounders in orbit. The company also has two radar instruments that were launched in 2023 and were influenced by NASA’s RainCube instrument — the first CubeSat equipped with an active precipitation radar.
More CubeSats leads to more accurate weather data because there are more opportunities each day — revisits — to collect data. “With a fleet size of 18, we can easily get our revisit rate down to under an hour, maybe even 40 to 45 minutes in most places. It has a huge impact on short-term forecasts,” Munchak said.
Having access to an atmospheric sounder that had already flown in space and had more than 10 years of testing was extremely useful as Tomorrow.io planned its fleet. “It would not have been possible to do this nearly as quickly or nearly as affordably had NASA not paved the way,” said Jennifer Splaingard, Tomorrow.io’s senior vice president for space and sensors.
A Cycle of Innovation
The relationship between NASA and industry is symbiotic. NASA and its grantees can drive innovation and test new tools, equipping American businesses with novel technologies they may otherwise be unable to develop on their own. In exchange, NASA gains access to low-cost data sets that can supplement information gathered through its larger science missions.
Tomorrow.io was among eight companies selected by NASA’s Commercial SmallSat Data Acquisition (CSDA) program in September 2024 to equip NASA with data that will help improve weather forecasting models. “It really is a success story of technology transfer. It’s that sweet spot, where the government partners with tech companies to really take an idea, a proven concept, and run with it,” Splaingard said.
By Gage Taylor
NASA’s Goddard Space Flight Center, Greenbelt, Md.
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Last Updated Sep 02, 2025 Related Terms
Earth Hurricanes & Typhoons TROPICS (Time-Resolved Observations of Precipitation Structure and Storm Intensity with a Constellation of Smallsats) View the full article
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By European Space Agency
Less than three weeks since the first MetOp Second Generation weather satellite, MetOp-SG-A1, was launched, this remarkable new satellite has already started transmitting data from two of its cutting-edge instruments, offering a tantalising glimpse of what’s to come.
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