Searching for proteins on Europa
Europa, one of Jupiter’s largest moons, is among the most compelling targets in the search for extraterrestrial life. It is believed to have a subsurface ocean of liquid water - tens of kilometers deep - beneath its outer ice shell - that could harbor the conditions necessary for life. Two space missions en route to Jupiter are expected to study Europa: NASA’s Europa Clipper, launched in October 2024, and the European Space Agency’s JUICE mission, launched in April 2023.
Both missions will only perform flybys of Europa, mapping its surface and trying to determine whether conditions exist that could support life in the subsurface ocean. However, neither mission is equipped to search for direct chemical signs on the surface that could indicate biological activity in that ocean.
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Surface of Europa as captured by NASA’s Juno spacecraft
(Photo: NASA/JPL-Caltech/SwRI/MSSS)
A new study by scientists from the Weizmann Institute of Science proposes a way to do just that—by focusing on the search for three amino acids, the fundamental building blocks of proteins, essential to life on Earth.
“We know that Europa’s surface is geologically very young, suggesting active resurfacing and material exchange with the internal ocean. In the past, we’ve seen evidence of water plumes erupting from its surface. On the other hand, we also know that Europa’s surface is bombarded with intense radiation from both Jupiter’s strong magnetic field and from solar ultraviolet light - since Europa lacks an atmosphere,” explains Dr. Gidi Yoffe, a postdoctoral researcher from the Department of Earth and Planetary Sciences at the Weizmann Institute, who led the study with Prof. Yohai Kaspi, in an interview with the Davidson Institute.
“Our study aimed to answer two key questions: If organic material reaches the surface, how long can it survive before radiation breaks it down? And how can we detect and characterize it remotely, without landing on Europa or drilling into its ice—both of which are extremely challenging and not currently planned?”
Yoffe, Kaspi, and their colleagues looked for biosignatures that could be detectable remotely. Their approach focused on fluorescent compounds—molecules that absorb light at one wavelength and emit it at another. In a recent paper published in Astrobiology, the researchers reported that the best candidates are three aromatic amino acids—meaning they contain a ring of carbon atoms.
“These amino acids—phenylalanine, tryptophan, and tyrosine—are complex molecules that are produced almost exclusively through biological processes, and we can identify them remotely using a laser, even at very low concentrations, such as one in ten million molecules,” said Yoffe.
“Moreover, we showed that these molecules can survive for decades within relatively fresh ice on Europa’s surface. So if, for example, a geyser erupts and deposits ice on the surface, we could detect these molecules in the resulting ice even 50 or 100 years later.”
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Yohai Kaspi (left) and Gidi Yoffe
(Photo: Nimrod Gabriel, Weizmann Institute of Science)
“The findings give reason for optimism: if there is indeed biologically sourced material reaching Europa’s surface, there’s a good chance we’ll be able to find it,” Kaspi added. “The study also gives us a better idea of where on Europa’s surface such materials might be located—but we’ll know even more once we receive mapping data from the two missions on their way there.”
Kaspi isn’t content with just developing theoretical methods to search for life on Europa. In recent months, he has been promoting an initiative to launch an Israeli spacecraft for a close flyby of Europa, equipped with a laser and an ultraviolet camera to put the theory to the test. “It would be a modest mission, using a small spacecraft and just a few instruments, and so it could be far, far cheaper than complex endeavors like JUICE or Europa Clipper,” Kaspi concluded.
A dwarf energes, a planet fades
Our solar system currently has nine celestial bodies officially classified as dwarf planets, but that number may soon increase. Last week, a research team announced the discovery of a new candidate: 2017 OF₂₀₁, a planetary body likely about 700 kilometers in diameter.
Its orbit is far beyond Pluto’s and highly elliptical—ranging from 44 astronomical units (AU) (6.6 billion kilometers) at its closest to the Sun, to a staggering 1,600 AU (240 billion kilometers) at its farthest. It takes 25,000 Earth years to complete a single orbit. For comparison, Pluto orbits between 30 and 50 AU.
The object was identified by a team led by Siao Cheng at the Institute for Advanced Study in Princeton, USA. By systematically analyzing images from two sky surveys, the team found that 2017 OF₂₀₁ was captured 19 times between 2011 and 2018—when it was relatively close to the Sun. This wealth of observations enabled them to calculate its orbit with high precision.
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According to the researchers, the discovery may also shed light on a long-debated mystery: Is there a ninth planet in the solar system? About a decade ago, researchers proposed the existence of a large, distant planet based on indirect evidence—suggesting an orbit around 600 AU from the Sun.
However, no direct observations have confirmed it, and other studies have since challenged the idea without offering conclusive proof. In a new study, published as a preprint and not yet peer-reviewed, researchers ran simulations of 2017 OF₂₀₁’s orbit with and without a hypothetical ninth planet.
Their conclusion: the absence of such a planet makes the current orbit of the dwarf planet stable. If a ninth planet did exist, the combined gravitational pull of it and Neptune would likely have ejected 2017 OF₂₀₁ from the solar system within 100 million years.
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A likely dwarf planet about 700 km wide, orbiting the Sun every 25,000 years. 2017 OF201 as seen by the CFHT telescope
(Photo: via study)
Samples from an asteroid and a comet
Two weeks ago, China launched an ambitious mission to collect samples from a relatively near-Earth asteroid—and later from a more distant comet. The Tianwen-2 spacecraft lifted off last Wednesday night aboard a Long March 3B rocket from the Xichang launch site in southwest China. The China Aerospace Science and Technology Corporation (CASC) a successful launch and orbital insertion shortly after liftoff.
The mission’s first target is asteroid 469219 Kamoʻoalewa, a narrow, elongated body estimated to be 40–100 meters long. It follows a path close to Earth and even shares part of Earth’s orbit. Discovered in 2016, it is thought to possibly be a lunar fragment ejected by an ancient asteroid impact.
Tianwen-2 is expected to reach it within a year, where it will use cameras, spectrometers, and other instruments to gather close-up data and attempt sample collection—potentially by landing, depending on surface conditions. The spacecraft will then return to Earth’s vicinity and release a capsule to deliver the samples safely to the ground.
Following the sample return—scheduled to happen in about two years—the spacecraft will perform a gravity assist maneuver using Earth’s gravity to increase its velocity and set course for a rendezvous with comet 311P/PANSTARRS, which orbits the Sun in the asteroid belt between Mars and Jupiter. The encounter is expected in 2035.
This object, approximately 400 meters in diameter, has the orbit of an asteroid but displays characteristics of a comet, most notably a long tail of ejected material. Observations by the Hubble Space Telescope have shown it has six such tails.
The spacecraft is also expected to sample this ejected material and analyze its composition using onboard instruments. Researchers hope the findings will provide insights into the comet’s history—and that of the solar system as a whole.
After the sample return—expected in about two years—the spacecraft will perform an Earth gravity assist maneuver to gain speed and set a course for comet 311P/PANSTARRS, located in the asteroid belt between Mars and Jupiter.
The rendezvous is planned for 2035. Although the object follows an asteroid-like orbit, it displays classic comet behavior, including multiple tails of ejected material—six, according to Hubble Space Telescope observations. Tianwen-2 will also analyze this ejected material and its composition using onboard instruments. Researchers hope the findings will provide insights into the comet’s history—and by extension to the history of the solar system.
The Tianwen mission series reflects China’s growing ambition to establish itself as a major space power, not just in Earth orbit but also in planetary exploration. Tianwen-1, launched in 2020, included a Mars orbiter and a lander-rover—the first non-American rover to operate on Mars. The upcoming Tianwen-3 mission, scheduled for 2028, is expected to return to Mars and even bring back soil samples. Tianwen-4 is aimed at exploring Jupiter and its moons, and may potentially continue on to Uranus.
Fading hints of alien life
Last month, scientists reported a potential detection of dimethyl sulfide (DMS) in the atmosphere of exoplanet K2-18b, about 124 light-years away. On Earth, DMS is produced solely by biological activity, leading to cautious speculation about the possibility of life. The finding was based on spectral data from the James Webb Space Telescope, which analyzes the composition of distant atmospheres by measuring how light passes through them.
However, three new preprint studies now challenge that interpretation. One study reanalyzed the James Webb data and found insufficient evidence to confirm the presence of DMS in the planet’s atmosphere. Another study identified flaws in the probability calculations used by the original researchers. A third study presented a list of dozens of compounds that could produce a similar spectral signature.
The research teams are now awaiting further data from additional observations by the James Webb Telescope, in hopes of reaching a more definitive conclusion.
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An artist’s impression of exoplanet K2-18b
(Illustration: NASA, ESA, CSA, Joseph Olmsted (STScI))
Progress and setback for Starship
Last week, SpaceX completed the ninth test flight of its Starship system. For the first time, the upgraded version of the spacecraft—successfully reached space, following two previous failures. However, about 30 minutes after launch, the vehicle entered an uncontrolled spin, preventing a controlled reentry, and ultimately exploded at an altitude of around 60 kilometers above the Indian Ocean.
Several planned experiments were also missed during the flight. These included a planned engine re-ignition in space and the deployment of dummy satellites, which had to be canceled after the cargo bay doors failed to open.
The flight also marked the first reuse of a Super Heavy booster, previously flown in the seventh test and successfully caught by the launch tower arms. This time, no tower catch was planned; instead, the booster attempted a controlled descent over the ocean at a steeper angle. That maneuver was only partially successful, as the booster exploded before completing the landing maneuver.
Despite the setbacks, SpaceX gathered valuable data and remains optimistic about further progress in future test flights.