esa Archives

September 5, 2024September 9, 2024 by Matt Williams

Ouch! A Monster Asteroid Crashed Into Ganymede 4 Billion Years Ago, Rolling it Over

Artist's impression of the large impact that caused Ganymede to reorient itself 4 billion years ago. © HIRATA Naoyuki

Jupiter’s moon, Ganymede, is a fascinating celestial body. Measuring 5,268 km (3,272 mi) in diameter, it is also the largest satellite in the Solar System and even larger than Mercury, which measures 4,880 km (3,032 mi) in diameter. Like Europa, it has an interior ocean and is one of the few bodies in the Solar System (other than the gas giants) with an intrinsic magnetic field. The presence of this field also means Ganymede experiences aurorae circling the regions around its northern and southern poles due to interaction with Jupiter’s magnetic field.

In addition, based on its surface craters, scientists believe that Ganymede experienced a powerful impact with an asteroid about 4 billion years ago. This asteroid was about 20 times larger than the Chicxulub asteroid that caused the extinction of the dinosaurs, or the Cretaceous–Paleogene extinction event (ca. 66 million years ago). According to a recent study by Naoyuki Hirata of Kobe University, this impact occurred almost precisely on the meridian farthest away from Jupiter. This caused a reorientation of Ganymede’s rotational axis and allowed Hirata to determine exactly what type of impact took place.

September 4, 2024September 4, 2024 by Evan Gough

A Surprise Asteroid Lit Up the Sky Over the Philippines

This image shows the predicted path over the Philippines for the surprise asteroid 2024 RW1. It's small and will burn up harmlessly. Image Credit: Catalina Sky Survey/ESA

With all of humanity’s telescopic eyes on the sky, it’s rare for an asteroid to take us by surprise. But that’s what happened this morning in the sky over the Philippines. Only hours after it was detected, it burned up in a bright flash above the island of Luzon.

September 4, 2024September 4, 2024 by Matt Williams

A Review of Humanity’s Planned Expansion Between the Earth and the Moon

Artist's impression of astronauts on the lunar surface, as part of the Artemis Program. Credit: NASA

Between Low Earth Orbit (LEO) and the Moon, there is a region of space measuring 384,400 km (238,855 mi) wide known as Cislunar space. In the coming decades, multiple space agencies will send missions to this region to support the development of infrastructure that will lead to a permanent human presence on the Moon. This includes orbital and surface habitats, landing pads, surface vehicles, technologies for in-situ resource utilization (ISRU), and other elements that will enable the long-term exploration and development of the lunar surface.

For all parties concerned, Cislunar space holds immense potential in terms of scientific, commercial, and military applications. The vastly increased level of activity on and around the Moon makes space domain awareness (SDA) – knowledge of all operations within a region of space – paramount. It is also necessary to ensure the continued success and utilization of the covered region. In a recent paper, a team of aerospace engineers considered the missions planned for the coming decades and evaluated the state and shortcomings of their space domain awareness.

September 4, 2024September 4, 2024 by Mark Thompson

Europe is Sending a Drill to the Moon to Search for Water

ESA's Prospect package, including drill and a miniaturised laboratory, will fly to the Moon’s South Polar region in search of volatiles, including water ice, as part of NASA’s Commercial Lunar Payload Services initiative.

The Moon has been a source of interest of late largely due to the focus on getting humans back to the Moon. Future human explorers though will likely be there to stay in permanent lunar bases. Making this a reality means it is of vital importance to harvest materials from the Moon and water is just one of them. Recently, ESA Announced they have secured a ride to the Moon for their Prospect package in 2027. It consists of a drill and tiny laboratory that will hunt for water and other volatiles, paving the way for human exploration.

August 30, 2024August 30, 2024 by David Dickinson

ESA Cluster Satellite to Reenter in Early September

The first of a set of groundbreaking Cluster satellites is set for a controlled reentry next week.

The European Space Agency is paving the way in controlled reentry technology. ESA recently announced that plans to terminate the first of four Cluster satellites is about to come to fruition in early September, with the reentry of Salsa.

August 29, 2024August 31, 2024 by Matt Williams

Remember those Impossible Galaxies Found by JWST? It Turns Out They Were Possible After All

This is a small portion of the field observed by NASA’s James Webb Space Telescope’s NIRCam (Near-Infrared Camera) for the Cosmic Evolution Early Release Science (CEERS) survey. It is filled with galaxies. The light from some of them has traveled for over 13 billion years to reach the telescope. Credit: NASA, ESA, CSA, Steve Finkelstein (University of Texas at Austin)

When the James Webb Space Telescope provided astronomers with a glimpse of the earliest galaxies in the Universe, there was some understandable confusion. Given that these galaxies existed during “Cosmic Dawn,” less than one billion years after the Big Bang, they seemed “impossibly large” for their age. According to the most widely accepted cosmological model—the Lambda Cold Dark Matter (LCDM) model—the first galaxies in the Universe did not have enough time to become so massive and should have been more modestly sized.

This presented astronomers with another “crisis in cosmology,” suggesting that the predominant model about the origins and evolution of the Universe was wrong. However, according to a new study by an international team of astronomers, these galaxies are not so “impossibly large” after all, and what we saw may have been the result of an optical illusion. In short, the presence of black holes in some of these early galaxies made them appear much brighter and larger than they actually were. This is good news for astronomers and cosmologists who like the LCDM the way it is!

August 29, 2024August 29, 2024 by Matt Williams

Webb Discovers Six New “Rogue Worlds” that Provide Clues to Star Formation

This stunning new mosaic of images from the NASA/ESA/CSA James Webb Space Telescope showcases the nearby star-forming cluster, NGC 1333. Credit: ESA/Webb, NASA & CSA, A. Scholz, K. Muzic, A. Langeveld, R. Jayawardhana

Rogue Planets, or free-floating planetary-mass objects (FFPMOs), are planet-sized objects that either formed in interstellar space or were part of a planetary system before gravitational perturbations kicked them out. Since they were first observed in 2000, astronomers have detected hundreds of candidates that are untethered to any particular star and float through the interstellar medium (ISM) of our galaxy. In fact, some scientists estimate that there could be as many as 2 trillion rogue planets (or more!) wandering through the Milky Way alone.

In recent news, a team of astronomers working with the James Webb Space Telescope (JWST) announced the discovery of six rogue planet candidates in an unlikely spot. The planets, which include the lightest rogue planet ever identified (with a debris disk around it), were spotted during Webb‘s deepest survey of the young nebula NGC 1333, a star-forming cluster about a thousand light-years away in the Perseus constellation. These planets could teach astronomers a great deal about the formation process of stars and planets.

August 27, 2024August 27, 2024 by Matt Williams

Massive Stars Shine in This Ultraviolet View From Hubble

NGC 346 is nestled within the Small Magellanic Cloud, a small satellite galaxy to our Milky Way. Credit: NASA/ESA/STScI/ Gladys Kober

Just outside the Milky Way Galaxy, roughly 210,000 light-years from Earth, there is the dwarf galaxy known as the Small Magellanic Cloud (SMC). Measuring about 18,900 light-years in diameter and containing roughly 3 billion stars, the SMC and its counterpart – the Large Magellanic Cloud (LMC) – orbit the Milky Way as satellite galaxies. Scientists are particularly interested in these satellites because of what they can teach us about star formation and the process where galaxies evolve through mergers, which is something the Milky Way will do with these two galaxies someday.

Another interesting feature of the SMC is the spectacular star cluster known as NGC 346, located near the center of the brightest star-forming region in the SMC, the hydrogen-rich nebula designated N66. Yesterday, NASA released a new image of this star cluster acquired by the venerable Hubble Space Telescope, which provides a unique and breathtaking view of this star cluster. These images were made possible thanks to Hubble’s sharp resolution and unique ability to make sensitive ultraviolet observations.

August 21, 2024August 21, 2024 by Matt Williams

Debris from DART could Hit Earth and Mars Within a Decade

The asteroid Dimorphos was captured by NASA’s DART mission just two seconds before the spacecraft struck its surface on Sept. 26, 2022. Observations of the asteroid before and after impact suggest it is a loosely packed “rubble pile” object. Credit: NASA/JHUAPL

On Sept. 26th, 2022, NASA’s Double Asteroids Redirect Test (DART) collided with Dimorphos, the small moonlet orbiting the larger asteroid Didymos. In so doing, the mission successfully demonstrated a proposed strategy for deflecting potentially hazardous asteroids (PHAs) – the kinetic impact method. By October 2026, the ESA’s Hera mission will rendezvous with the double-asteroid system and perform a detailed post-impact survey of Dimorphos to ensure that this method of planetary defense can be repeated in the future.

However, while the kinetic method could successfully deflect asteroids so they don’t threaten Earth, it could also create debris that might reach Earth and other celestial bodies. In a recent study, an international team of scientists explored how this impact test also presents an opportunity to observe how this debris could someday reach Earth and Mars as meteors. After conducting a series of dynamic simulations, they concluded that the asteroid ejecta could reach Mars and the Earth-Moon system within a decade.

August 16, 2024August 16, 2024 by David Dickinson

See JUICE Next Week During Its Earth-Moon Flyby

Well-placed observers have a rare opportunity to see an interplanetary spacecraft early next week.

If skies are clear, dedicated observers and imagers have a shot early next week at seeing a spacecraft headed to Jupiter.

The Mission is JUICE, the European Space Agency’s Jupiter Icy Moons Explorer. Launched atop an Ariane-5 rocket from Kourou Space Center in French Guiana on April 14^th, 2023, JUICE is due to arrive at Jupiter in 2031. But first, the spacecraft will perform several planetary flybys to pick up speed, hurdling it towards the outer solar system.