Artist rendering of the X-37B conducting an aerobraking maneuver using the drag of Earth’s atmosphere. Credit: Boeing Space
The X-37B Orbital Test Vehicle (OTV) has been shrouded in mystery since its maiden flight in 2011. Designed by Boeing and operated by the U.S. Space Force (USSF), this remotely operated, reusable space plane is designed to operate in Low-Earth Orbit (LEO), 240 to 800 km (150 to 500 mi) above the Earth, and test reusable vehicle technologies that support long-term space objectives. On December 29th, 2023, the X-37B began its seventh mission (OTV-7) and has reportedly been conducting experiments on the effects of space radiation and testing Space Domain Awareness (SDA) technologies.
As part of this mission, the X-37B will soon begin executing a series of novel maneuvers to change its orbit around Earth. These maneuvers will consist of the spacecraft brushing against Earth’s upper atmosphere to shed speed and lower its orbit without expending much fuel—a technique known as “aerobraking.” This is the first time the X-37B has performed such a maneuver, which will help it evade detection by potentially hostile nations and perform undetected low passes over Earth during future missions.
Ever since the advent of space exploration we have seen some amazing images of the planets. New technology often brings with it a new perspective and we have been reminded of this again just recently with images from the Hubble Space Telescope (HST) and New Horizons spacecraft. The two objects simultaneously imaged Uranus from different perspectives in an attempt to predict what astronomers would see when they look at exoplanets orbiting other stars.
SpaceX's Falcon Heavy rocket sends NASA's Europa Clipper into space from its Florida launch pad. (NASA Photo / Kim Shiflett)
NASA’s Europa Clipper spacecraft today began its six-year cruise to the Jupiter system, with the goal of determining whether one of the giant planet’s moons has the right stuff in the right setting for life.
The van-sized probe was sent into space from NASA’s Kennedy Space Center atop a SpaceX Falcon Heavy rocket at 12:06 p.m. ET (16:06 UTC). A little more than an hour after launch, the spacecraft separated from its launch vehicle to begin a roundabout journey of 1.8 billion miles (2.9 billion kilometers) from Earth orbit to Europa.
For decades, scientists have been collecting evidence that Europa harbors a hidden ocean of salty water beneath its icy shell. Or are they hidden lakes? Europa Clipper is built to characterize the moon’s surface, and what’s beneath that surface, to an unprecedented degree.
This image shows the galaxy REBELS-25 as seen by the Atacama Large Millimeter/submillimeter Array (ALMA), overlaid on an infrared image of other stars and galaxies. Courtesy ESO.
The early Universe continues to offer surprises and the latest observations of infant galaxies are no exception. Astronomers found a surprisingly Milky Way-like galaxy that existed more than 13 billion years ago. That was a time when the Universe was really just an infant and galaxies should still be early in their formation. A well-formed one in such early history is a bit of a surprise.
The newly discovered galaxy is called REBELS-25. It was found as part of the “Reionization Era Bright Emission Line Survey (REBELS) survey using the Atacama Large Millimeter Array (ALMA) in Chile. The idea of the survey is to search out and measure early galaxies.
REBELS-24 is a massive disc-like galaxy with structures that look like spiral arms. That’s pretty similar to our Milky Way Galaxy. It’s more than 13 billion years old and took billions of years to evolve into its present shape. Like REBELS-25, the Milky Way began as a clumpy, disorganized proto-galaxy not long after the Universe began. It merged with other protogalaxies and evolved into a beautiful spiral shape. It appears to be actively forming stars and is incredibly massive for such a young galaxy.
Early Spirals Aren’t New
So, REBELS-25 raises a big question: why is it so massive and well-evolved at a time when the infant Milky Way was still a clump? That’s what astronomers are working to figure out. “According to our understanding of galaxy formation, we expect most early galaxies to be small and messy looking,” said Jacqueline Hodge, an astronomer at Leiden University, the Netherlands. The fact that REBELS-25 looks so “modern” after less than a billion years does—in a sense—rebel against the generally accepted theories about galaxy formation and evolution.
This isn’t the first time that astronomical observations uncovered early spirals. JWST observations suggest that perhaps a third of early galaxies are already spirals in the infant Universe. Its Cosmic Evolution Early Release Science Survey (CEERS) found many of these in the first 700 million years of cosmic history. So, finding this one looking almost “modern” some 13 billion years ago just adds to the mystery of their formation.
REBELS-25 showed up in ALMA observations, which also gave hints that it had a rotating disk. A set of follow-up observations confirmed the rotation of this galaxy and its spiral arm structures. In addition, the ALMA data found hints of a central bar (just like our Milky Way galaxy has). “ALMA is the only telescope in existence with the sensitivity and resolution to achieve this,” said Renske Smit, a researcher at Liverpool John Moores University in the UK and part of the team that worked on this discovery.
The ALMA data produced an image of REBELS-25 (left) and a map of gas motions in this galaxy which lies more than 13 billion light-years away. Blue coloring indicates movement towards Earth. Red indicates movement away from Earth, with a darker shade representing faster movement. In this case, the red-blue divide of the image shows clearly that the object is rotating, making REBELS-25 the most distant and early (13 billion years old) rotating disc galaxy ever discovered. Courtesy ESO.
Surprisingly, the ALMA data also hinted at more developed features similar to those of the Milky Way. It looks like there’s a central elongated bar, and even spiral arms in REBELS0-25. “Seeing a galaxy with such similarities to our own Milky Way, that is strongly rotation-dominated, challenges our understanding of how quickly galaxies in the early Universe evolve into the orderly galaxies of today’s cosmos,” said Lucie Rowland, a doctoral student at Leiden University who led the research into REBELS-25. “Finding further evidence of more evolved structures would be an exciting discovery, as it would be the most distant galaxy with such structures observed to date.”
What Does This Mean for Galaxy Evolution?
As astronomers discover more of these well-evolved galaxies in the early Universe, they’ll have to adjust the working model of galactic birth and evolution. In that model, the baby galaxies are clumps of stars and gas that come together in collisions and cannibalism to form larger galaxies. It’s typically considered a messy and turbulent time in cosmic history. Infant galaxies collided and grew. They combined their stars and gases to make larger structures. Over time they begin to rotate, which also influences the formation of structures inside the galaxy. Further collisions add more mass to the galaxy, and they also spur bursts of star formation. All of this takes billions of years to accomplish. Or so astronomers always thought.
REBELS-25 and other early spirals challenge that general model. For one thing, REBELS-25 looks like a galaxy that’s evolving at an accelerated pace. Compared to the Milky Way’s ponderous billions of years of evolution, REBELS-25 is going at warp speed. That implies something is pushing that acceleration. T he big thing now will be to explain its advanced evolution at a very young age.
The REBELS program should help astronomers understand more about the processes at work only a few hundred million years after the Big Bang. That survey will supply large enough amounts of data about high-mass galaxies in the early Universe. Those samples should allow astronomers to do targeted studies of more galaxies using both ALMA and JWST. Both observatories are powerful enough to give detailed looks at individual galaxies in those very early epochs of cosmic history.
Cosmology has had several ground-breaking discoveries over the last 100+ years since Einstein developed his theory of relativity. Two of the most prominent were the discovery of the Cosmic Microwave Background (CMB) in 1968 and the confirmation of gravitational waves in 2015. Each utilized different tools, but both lent credence to the Big Bang Theory, which relates to the universe’s formation. However, we still don’t understand a vital part of that formation, and a new review paper by Rishav Roshan and Graham White at the University of Southampton suggests that we might be able to make some headway on our one-second “gap” in knowledge by using our newfound understanding of gravitational waves.
Illustration of the asteroid Bennu. Credit: NASA Jet Propulsion Laboratory
There are four fundamental forces in the Universe. These forces govern all the ways matter can interact, from the sound of an infant’s laugh to the clustering of galaxies a billion light-years away. At least that’s what we’ve thought until recently. Things such as dark matter and dark energy, as well as a few odd interactions in particle physics, have led some researchers to propose a fifth fundamental force. Depending on the model you consider, this new force could explain dark matter and cosmic expansion, or it could interact with elemental particles we haven’t yet detected. There are lots of theories about this hypothetical force. What there isn’t a lot of is evidence. So a new study is looking for evidence in the orbits of asteroids.
Perhaps you’ve heard of the popular Netflix show and the science fiction novel on which it is based, The Three-Body Problem, by Chinese science fiction author Liu Cixin. The story’s premise is a star system where three stars orbit each other, which leads to periodic destruction on a planet orbiting one of them. As Isaac Newton described in his Philosophiæ Naturalis Principia Mathematica, the interaction of two massive bodies is easy to predict and calculate. However, the interaction of three bodies leads is where things become unpredictable (even chaotic) over time.
This problem has fascinated scientists ever since and remains one of the most famous unsolved mysteries in mathematics and theoretical physics. The theory states that the interaction of three gravitationally bound objects will evolve chaotically and in a way that is completely detached from their initial positions and velocities. However, in a recent study, an international team led by a researcher from the Niels Bohr Institute ran millions of simulations that showed “isles of regularity in a sea of chaos.” These results indicate that there could be a solution, or at least some predictability, to the Three-Body Problem.
A simulation of galaxies during the era of deionization in the early Universe. Credit: M. Alvarez, R. Kaehler, and T. AbelCredit: M. Alvarez, R. Kaehler, and T. Abel
The “Epoch of Reionization” was a critical period for cosmic evolution and has always fascinated and mystified astronomers. During this epoch, the first stars and galaxies formed and reionized the clouds of neutral hydrogen that permeated the Universe. This ended the Cosmic Dark Ages and led to the Universe becoming “transparent,” what astronomers refer to as “Cosmic Dawn.” According to our current cosmological models, reionization lasted from 380,000 to 1 billion years after the Big Bang. This is based on indirect evidence since astronomers have been unable to view the Epoch of Reionization directly.
Investigating this period was one of the main reasons for developing the James Webb Space Telescope (JWST), which can pierce the veil of the “dark ages” using its powerful infrared optics. However, observations provided by Webb revealed that far more galaxies existed in the early Universe than previously expected. According to a recent study, this suggests that reionization may have happened more rapidly and ended at least 350 million years earlier than our models predict. Once again, the ability to peer into the early Universe has produced tensions with prevailing cosmological theories.
SpaceX's Starship Super Heavy booster settles back into the arms of its launch-pad cradle in Texas. (Credit: SpaceX)
For the first time ever, SpaceX has followed through on a Starship test launch by bringing back the Super Heavy booster for an on-target catch in the arms of its “Mechazilla” launch-tower cradle in Texas.
“This is a day for the engineering history books,” SpaceX launch commentator Kate Tice said.
Today’s successful catch marks a giant step toward using — and reusing — Starship for missions ranging from satellite deployments to NASA’s moon missions to migrations to Mars.
New NASA-led research suggests a sodium cloud seen around the exoplanet WASP-49 b might be created by a volcanic moon, which is depicted in this artist’s concept. Jupiter’s fiery moon Io produces a similar cloud. Credit: NASA/JPL-Caltech
In 2012, astronomers detected a gas giant transiting in front of WASP-49A, a G-type star located about 635 light-years from Earth. The data obtained by the WASP survey indicated that this exoplanet (WASP-49 b) is a gas giant roughly the same size as Jupiter and 37% as massive. In 2017, WASP-49 b was found to have an extensive cloud of sodium, which was confounding to scientists. Further observations in 2019 using the Hubble Space Telescope detected the presence of other minerals, including magnesium and iron, which appeared to be magnetically bound to the gas giant.
WASP-49 b and its star are predominantly composed of hydrogen and helium, with only trace amounts of sodium – not enough to account for this cloud. In addition, there was no indication of how this sodium cloud was ejected into space. In our Solar System, gas emissions from Jupiter’s volcanic moon Io create a similar phenomenon. In a recent study, an international team led by scientists from NASA’s Jet Propulsion Laboratory found potential evidence of a rocky, volcanic moon orbiting WASP-49 b. While not yet confirmed, the presence of a volcanic exomoon around this gas giant could explain the presence of this sodium cloud.
