SPACE/COSMOS
The interstellar comet 3I/ATLAS was born somewhere much different from our solar system
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A new study of the interstellar comet 3I/ATLAS led by the University of Michigan shows that its water has a remarkably high content of deuterium. This form of hydrogen is comparatively less abundant in our solar system, enabling researchers to glean new insights about other planetary processes at work in our galaxy. Image credit: U-M News/Hans Anderson
view moreCredit: U-M News/Hans Anderson
Less than a year ago, astronomers discovered a comet soaring through our sky that was not from our solar system.
Although we still don't know where this interstellar object called 3I/ATLAS came from, research led by the University of Michigan has revealed new insights about its birthplace. Wherever that was, it was much colder than the environment that created our solar system.
The new finding is based on the observation that 3I/ATLAS is remarkably rich in a specific type of water that contains deuterium. The team's study, which is published in the journal Nature Astronomy, was made possible, in part, by federal support from NASA, the U.S. National Science Foundation and Chile's National Research and Development Agency.
"Our new observations show that the conditions that led to the formation of our solar system are much different from how planetary systems evolved in different parts of our galaxy," said Luis Salazar Manzano, lead author of the new study and a doctoral student in the U-M Department of Astronomy.
Water is made of two hydrogen atoms and one oxygen atom, hence its H2O formula. In typical water molecules, though, those hydrogen atoms have just one proton at their core. In the comet's water, a high ratio of its water molecules contain deuterium, a form of hydrogen with the standard issue proton plus a neutron. These heavier forms of water also exist on Earth, but in much lower quantities than were observed in 3I/ATLAS.
"The amount of deuterium with respect to ordinary hydrogen in water is higher than anything we've seen before in other planetary systems and planetary comets," Salazar Manzano said. In fact, the ratio was 30 times that of any comet in our solar system, Salazar Manzano said, and 40 times the value found in the water in our oceans.
These ratios tell researchers about the conditions that were present where these celestial objects formed, allowing them to compare the birthplace of 3I/ATLAS with our solar system when planets and comets were forming. In particular, this result means 3I/ATLAS came from somewhere colder and with lower levels of radiation, said Teresa Paneque-Carreño, a co-leader of the new study and U-M assistant professor of astronomy.
"This is proof that whatever the conditions were that led to the creation of our solar system are not ubiquitous throughout space," Paneque-Carreño said. "That may sound obvious, but it's one of those things that you need to prove."
Accomplishing an unprecedented study like this required a lot of things going right, the team said. It started with astronomers discovering 3I/ATLAS early enough to enable follow-up studies, Paneque-Carreño said.
With the comet's timely discovery, Salazar Manzano and other collaborators could secure time at the MDM Observatory in Arizona, where they saw some of the earliest evidence of gas emission from the comet (MDM stands for Michigan, Dartmouth and the Massachusetts Institute of Technology, the observatory's original partners). That's when Salazar Manzano contacted Paneque-Carreño to collaborate, who brought expertise with the Atacama Large Millimeter/submillimeter Array, or ALMA, in Chile to further observe and characterize the comet’s chemical properties.
ALMA is sensitive enough to detect the subtle difference between deuterated and conventional water that the team could characterize the ratio between the two. This study represents the first time scientists have been able to perform this type of analysis on an interstellar object.
"Being at the University of Michigan and having access to these facilities was the key to making this work possible," Salazar Manzano said. "We were part of a team that was very talented and very experienced in multiple areas, all of us complemented each other and that's what allowed us to analyze and interpret these data sets."
This work also shows that it will be possible to characterize future interstellar objects in this way to learn more about what goes on planetary systems beyond our solar system. Although 3I/ATLAS is only the third interstellar object that astronomers have discovered to date, that count is likely to increase as new observatories join the search, Paneque-Carreño said—as long as we don't make it too hard on ourselves.
"We need to be taking care of our night skies and keeping them clear and dark so we can detect these tiny and faint objects," she said.
Additional funding for this work came from the Michigan Society of Fellows and the Heising-Simons Foundation. ALMA is a partnership between the European Southern Observatory, the NSF and Japan's National Institutes of Nature Sciences in cooperation with the Republic of Chile.
Journal
Nature Astronomy
Article Title
Water D/H in 3I/ATLAS as a probe of formation conditions in another planetary system
Article Publication Date
23-Apr-2026
Conceptualizing in situ energy station for Mars exploration
Preparing for human Mars exploration
Science China Press
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Left panel: collecting and processing the Martian atmosphere to a working state. Achieved through mechanical compression, cryogenic trapping or temperature swing adsorption. Middle panel: utilizing the Martian air as a working medium for heat-to-electricity conversion (nuclear reactor) and energy storage. Right panel: coupled chemical conversion module and biotechnology satisfy the fundamental resource needs for human survival on Mars.
view moreCredit: ©Science China Press
The field of deep space exploration is entering a crucial window period for leapfrog development towards long-term extraterrestrial habitation. In-situ resource utilization, power generation and storage, and life resource conversion are becoming increasingly crucial for the next phase of continuous human Mars exploration, relying on the simultaneous progress of theoretical methods, mission architectures, and engineering technologies. In comparison to Earth, the Martian atmosphere has lower pressure (∼600 Pa) and temperature (∼210 K). It is primarily composed of carbon dioxide (∼96%), with nitrogen (∼2%) and argon (∼2%) as secondary components. These gases can serve as a heat transfer medium and are in-situ sources of carbon and oxygen elements. Researchers believe that Martian air as the working medium for the space nuclear system, integrated with heat-to-electricity and chemical conversion, is paving the way for multimodal resource transformation on Mars. The implementation path- way includes three main steps: (1) Mar- tian atmospheric capture; (2) in-situ power generation and storage; and (3) life -support resources transformation, which may afford a fruitful insight.
1. MARTIAN ATMOSPHERIC CAPTURE
Martian atmosphere capture and pressurization: This can be achieved through three methods: mechanical compression, cryogenic capture, and adsorption compression. The rarefied Martian atmosphere (600 - 800 Pa) is compressed to the working pressure (>100 kPa). Each of the three methods has its own advantages and disadvantages in terms of energy consumption, compression ratio, and reliability. A comprehensive consideration of factors such as impurity tolerance, power supply, mission lifespan, and waste heat availability is required.
2. IN-SITU POWER GENERATION AND STORAGE
The reliance on solar energy for long-term manned missions in the extreme environment of Mars requires reevaluation. The Martian atmosphere serves as an ideal working medium for the secondary circuit of a space micro nuclear reactor. Its efficiency and power density are expected to surpass those of helium-xenon mixed gas, enabling a power supply at the level of hundreds of kilowatts. Coupled with high-energy-density lithium-Martian gas batteries for energy storage, it can alleviate the problems of power fluctuation and power distribution.
3. LIFE-SUPPORT RESOURCES TRANSFORMATION
The low-temperature waste heat from the recycling power generation module is used to provide heating for the Mars base. The medium-temperature CO2 exhaust gas is combined with hydrogen (through electrolysis of groundwater ice) through the Sabatier reaction to produce methane fuel and water. The high-temperature CO2 is electrolyzed in a solid oxide electrolysis cell to generate oxygen, meeting the life resource requirements of humans for heat/oxygen/fuel during human stay on Mars.
To further illustrate the practical application potential of the design framework, the energy requirements of the early manned Mars missions of the National Aeronautics and Space Administration are referenced, and a preliminary model is developed to evaluate the flow, power flow, and component weight of key nodes within the system. On the basis of verifying the engineering feasibility, it is revealed that in-situ atmospheric utilization has the potential to save more than twenty tons of payload (approximately 60% of the fuel weight of the Mars manned ascent and return vehicle) in the first future manned Mars exploration mission. It can be regarded as an infrastructure that is deployed by the spacecraft before the arrival of human astronauts.
The first crewed mission to Mars may be carried out within the next few decades. Currently, the in-situ resource utilization technology of the Martian atmosphere is still in the conceptual research stage. To bridge the gap, the following directions are recommended: (1) Explore the physical properties of multiple components in the Martian atmosphere, establish a test platform for simulating the thermophysical properties of the atmosphere, and improve the data to guide the development of thermal components; (2) Develop key components, including integrated compression-expansion-power rotating units, space microreactors, high-temperature CO₂ corrosion-resistant materials, long-service-life electrochemical systems, and Martian dust removal devices; (3) Conduct high-efficiency/high-power density integrated design of the system and optimize the material flow matching path in view of the low-pressure and low-gravity environment on Mars; (4) Combine artificial intelligence to establish an automatic control method for the energy system in extreme environments to adapt to the Mars changing environment fluctuations.
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