The United States Space Force has suspended its plan to establish a missile landing site in the Pacific Ocean, intended to test the use of commercial rockets for transporting large quantities of supplies to remote locations.
The proposed site was Johnston Atoll, a small group of islands about 1,300 kilometers southwest of Hawaii. Once a Cold War-era military base and later abandoned, the atoll is now closed to visitors and managed by the U.S. Fish and Wildlife Service.
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A comet with a long history. The orbit of the interstellar object 3I/ATLAS in the Milky Way (in red) and the orbit of our Sun (in yellow)
(Illustration: M. Hopkins/Ōtautahi-Oxford team)
The U.S. military newspaper Stars and Stripes reported that the Space Force suspended the program following opposition from environmental groups. In March, the Air Force announced an environmental review to assess the program’s potential impact on the islands’ ecosystem. Since then, many environmental organizations have raised concerns that the project would harm seabird populations on the atoll and disrupt the surrounding marine environment. A petition opposing the plan has gathered nearly 4,000 signatures.
The program called for building two landing pads on the islands, along with supporting infrastructure, to test rocket landings by private companies such as SpaceX. About ten landings per year were planned over a four-year testing period. SpaceX has previously stated that its Starships, designed for controlled vertical landings, could serve not only space missions — especially Mars colonization — but also deliver cargo and passengers at high speeds to virtually any location on Earth, including remote areas without airport infrastructure.
“The Department of the Air Force has elected to hold the preparation of the Johnston Atoll Environmental Assessment for a proposed rocket cargo landing demonstration on Johnston Atoll in abeyance while the service explores alternative options for implementation of the rocket cargo Vanguard program at a location other than Johnston Atoll,” Laurel Falls, an Air Force spokeswoman told the journal. The Air Force may also have more time than it thought: after nine test flights over more than two years, Starship is still far from operational readiness.
A week ago, an object originating from another solar system was discovered in our solar system, and this week it is already the focus of many studies aiming to decipher its composition and origin. Comet 3I/ATLAS is the third interstellar object ever detected, following ‘Oumuamua in 2017 and comet Borisov in 2019. This newcomer is traveling nearly twice as fast as its predecessors, streaking through our solar system at about 57 kilometers per second — over 200,000 kilometers per hour relative to the Sun. An observational study already posted to a preprint site found that this new visitor has a relatively reddish color, which increases the likelihood that it indeed came from outside our solar system. Another study points to its structural similarity to comets we’re familiar with.
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There’s a good chance complex molecules exist there, but the water may be too alkaline for life. Plumes from Enceladus as photographed by the Cassini spacecraft
(Photo: NASA/JPL/Space Science Institute)
“This thing’s coming in much faster than the other two, but it is actually within the range of velocities that we would predict in objects. So we don’t think that’s notable, but it’s moving fast up and down relative to the plane of the galaxy in a vertical velocity, so it gives us a clue about where it’s from. “Our model predicts that it’s from a star in the thick disc of the galaxy,” said Chris Lintott, professor of astrophysics at the University of Oxford, UK. The thick disk is a distinct region of the Milky Way — and other spiral galaxies — separate from the thin disk, where the spiral arms and our Sun reside. The thick disk typically contains older stars.
“[Comet 3I/ATLAS] is probably from an old star in the thick disc, and we think that it’s likely that this thing’s been out there for longer than the age of the Solar System.”
Lintott added. “There’s a two-thirds chance that it’s older than 7 billion, and that would explain the colour. So these things get processed by cosmic rays and turn red. I think the thing that’s most exciting for me is that if it is from the thick disk, we’re seeing an object from a part of the galaxy we’ve never seen one before.”
Lintott and his colleagues also quickly published their preliminary findings on the interstellar comet and posted them as a preprint. Unlike its two predecessors, 3I/ATLAS will give scientists plenty of time to study it, as it is expected to remain visible for many months. Though too small and distant to be seen with the naked eye, it’s easily observable through telescopes and will look even better when it reaches its closest approach to Earth — about 250 million kilometers away — this December.
In recent years, growing evidence suggests that several moons in our solar system harbor subsurface oceans of liquid water deep beneath ice shells tens of kilometers thick. Among the most intriguing is Enceladus, a moon of Saturn, which has drawn considerable interest since strong evidence for its hidden ocean emerged about two decades ago, mainly due to the tantalizing possibility that it could host life.
The Cassini spacecraft, which studied Saturn, its moons, and rings until its mission ended in 2017, documented jets of water erupting into space through cracks in Enceladus’s ice. Cassini even managed to fly through these plumes and sampled material from them, despite not being originally designed for such applications and having instruments with limited capability to analyze their composition.
Cassini was never intended to return to Earth, nd at the end of its mission, it was deliberately crashed into Saturn, along with the samples it had collected. But the data it transmitted remained with researchers. Now, a research team has used Cassini’s data to attempt to analyze the acidity of Enceladus’s ocean and concluded that it is highly basic (alkaline), near the upper limit for conditions that could potentially support the existence of life as we know it on Earth.
Acidity is measured using the pH scale, which indicates how acidic or basic (alkaline) a substance is. The scale ranges from 0 to 14: A pH of 7 is neutral, like distilled water; values below 7 indicate acidity, while values above 7 indicate alkalinity (or basicity). Earth’s oceans are slightly basic, with a pH around 8. In contrast, Enceladus’s ocean is much more alkaline, and researchers estimate its pH to be between 10.1 and 11.6, based on the ratios of various compounds.
“High pH tends to break apart biological polymers. However, we know that some microbes on Earth can tolerate the range of pH found on Enceladus,” said Christopher Glein, head of the research team, from the Southwest Research Institute (SwRI) in San Antonio, Texas. Metals become less soluble at higher pH, so iron may be scarce in Enceladus’ ocean. I think the best place to live would be on the seafloor. If you’re a microbe, you could directly ‘mine’ iron and other metals from minerals without relying on solubility. We might want to think about biofilms on Enceladus.”
Despite Glein’s optimism about the potential for life, it’s important to remember that we still don’t know the exact composition of Enceladus’s ocean. Previous studies suggest there’s a good chance of finding complex molecules there, but we won’t know for sure until we explore it directly. One future mission that could search for reliable signs of life is the Israeli Eureka initiative, which, if it moves forward, could survey the surface of Europa, Jupiter’s moon, and possibly Enceladus as well, in search of complex amino acids.