SPACE
Gigantic asteroid impact shifted the axis of Solar System's biggest moon
Kobe University
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Kobe University HIRATA Naoyuki was the first to realize that the location of an asteroid impact on Jupiter’s moon Ganymede is almost precisely on the meridian farthest away from Jupiter. This implied that Ganymede had undergone a reorientation of its rotational axis and allowed Hirata to calculate what kind of impact could have caused this to happen.
view moreCredit: HIRATA Naoyuki
Around 4 billion years ago, an asteroid hit the Jupiter moon Ganymede. Now, a Kobe University researcher realized that the Solar System's biggest moon's axis has shifted as a result of the impact, which confirmed that the asteroid was around 20 times larger than the one that ended the age of the dinosaurs on Earth, and caused one of the biggest impacts with clear traces in the Solar System.
Ganymede is the largest moon in the Solar System, bigger even than the planet Mercury, and is also interesting for the liquid water oceans beneath its icy surface. Like the Earth’s moon, it is tidally locked, meaning that it always shows the same side to the planet it is orbiting and thus also has a far side. On large parts of its surface, the moon is covered by furrows that form concentric circles around one specific spot, which led researchers in the 1980s to conclude that they are the results of a major impact event. “The Jupiter moons Io, Europa, Ganymede and Callisto all have interesting individual characteristics, but the one that caught my attention was these furrows on Ganymede,” says the Kobe University planetologist HIRATA Naoyuki. He continues, “We know that this feature was created by an asteroid impact about 4 billion years ago, but we were unsure how big this impact was and what effect it had on the moon.”
Data from the remote object is scarce making research very difficult, and so Hirata was the first to realize that the purported location of the impact is almost precisely on the meridian farthest away from Jupiter. Drawing from similarities with an impact event on Pluto that caused the dwarf planet’s rotational axis to shift and that we learned about through the New Horizons space probe, this implied that Ganymede, too, had undergone such a reorientation. Hirata is a specialist in simulating impact events on moons and asteroids, so this realization allowed him to calculate what kind of impact could have caused this reorientation to happen.
In the journal Scientific Reports, the Kobe University researcher now published that the asteroid probably had a diameter of around 300 kilometers, about 20 times as large as the one that hit the Earth 65 million years ago and ended the age of the dinosaurs, and created a transient crater between 1,400 and 1,600 kilometers in diameter. (Transient craters, widely used in lab and computational simulations, are the cavities produced directly after the crater excavation and before material settles in and around the crater.) According to his simulations, only an impact of this size would make it likely that the change in the distribution of mass could cause the moon’s rotational axis to shift into its current position. This result holds true irrespective of where on the surface the impact occurred.
“I want to understand the origin and evolution of Ganymede and other Jupiter moons. The giant impact must have had a significant impact on the early evolution of Ganymede, but the thermal and structural effects of the impact on the interior of Ganymede have not yet been investigated at all. I believe that further research applying the internal evolution of ice moons could be carried out next,” explains Hirata.
Interesting for its subsurface oceans, Ganymede is the final destination of ESA’s JUICE space probe. If everything goes well, the spacecraft will enter orbit around the moon in 2034 and will make observations for six months, sending back a wealth of data that will help answer Hirata’s questions.
This research was funded by the Japan Society for the Promotion of Science (grants 20K14538 and 20H04614) and the Hyogo Science and Technology Association.
Kobe University is a national university with roots dating back to the Kobe Commercial School founded in 1902. It is now one of Japan’s leading comprehensive research universities with nearly 16,000 students and nearly 1,700 faculty in 10 faculties and schools and 15 graduate schools. Combining the social and natural sciences to cultivate leaders with an interdisciplinary perspective, Kobe University creates knowledge and fosters innovation to address society’s challenges.
240903-Hirata-Ganymede-
On large parts of its surface, the Jupiter moon Ganymede is covered by furrows (right) that form concentric circles around one specific spot (left, red cross), which led researchers in the 1980s to conclude that they are the results of a major impact event.
240903-Hirata-Ganymede-Topography
Distribution of furrows and the location of the center of the furrow system shown in the hemisphere that always faces away from Jupiter (top) and the cylindrical projection map of Ganymede (bottom). The gray regions represent geologically young terrain without furrows. Furrows (green lines) exist only on geologically old terrains (black regions).
Credit
HIRATA Naoyuki
Journal
Scientific Reports
Method of Research
Computational simulation/modeling
Subject of Research
Not applicable
Article Title
Giant impact on early Ganymede and its subsequent reorientation
Article Publication Date
3-Sep-2024
Sulfurous acid H2SO3 - and it does exist
World's first proof under atmospheric conditions calls textbook opinion into question
Leibniz Institute for Tropospheric Research (TROPOS)
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The team that achieved the world's first detection of sulfurous acid (H2SO3) under atmospheric conditions in the TROPOS laboratory: Dr Erik H. Hoffmann, Dr Torsten Berndt and Dr Andreas Tilgner (from left to right).
view moreCredit: Ricarda Graefe, TROPOS
Leipzig. Once again, the atmosphere amazes us with its diverse chemical processes. For the first time, researchers at the Leibniz Institute for Tropospheric Research (TROPOS) in Leipzig have demonstrated the existence of sulfurous acid (H2SO3) under atmospheric conditions in the gas phase. The results were published in the journal Angewandte Chemie.
In contrast to the well-known sulfuric acid (H2SO4), sulfurous acid (H2SO3) is considered as compound that is difficult or impossible to access (produce). Textbooks suggest the possible formation of H2SO3 in aqueous sulfur dioxide (SO2) solution, although its existence in isolated form is considered impossible. However, despite great efforts using various spectroscopic methods, the experimental detection of H2SO3 in aqueous SO2 solution has so far been unsuccessful. Only the corresponding bases bisulphite HSO3- and sulphite SO32- were detectable.
The only experimental detection of H2SO3 to date was achieved by Helmut Schwarz's team at TU Berlin in 1988 using in-situ generation in a mass spectrometer. An extremely short lifetime under vacuum conditions in the range of 10 microseconds and more was estimated.
Theoretical calculations suggested the formation of H2SO3 as a possible reaction product of the gas-phase reaction of OH radicals, which are formed in the troposphere primarily from ozone and water molecules in the presence of UV radiation, with dimethyl sulfide (DMS). DMS is mainly produced by biological processes in the sea and is the largest biogenic sulfur source for the atmosphere, producing around 30 million tonnes annually.
The possible reaction pathway to H2SO3 starting from the DMS was investigated experimentally in the laboratory at TROPOS in Leipzig. The formation of H2SO3 in the gas phase was clearly demonstrated in flow reactors for atmospheric conditions. Under the experimental conditions, the sulfurous acid remained stable for half a minute regardless of the humidity. Longer residence times could not yet be investigated with the existing experimental setup. Therefore, H2SO3 could also exist sufficiently long enough in the atmosphere and have an influence on the chemical processes. The observed yield was even somewhat greater than theoretically assumed. "It was very impressive to see the clear H2SO3 signals in the spectrometer for a compound that had been assumed to be possibly "non-existent"," says Dr Torsten Berndt from TROPOS, who came up with the idea and carried out the experiments.
The new reaction pathway was then implemented in a global chemistry-climate model. The associated model simulations showed that around 8 million tons of H2SO3 are formed globally every year. "This pathway produces about 200 times more mass of H2SO3 than the direct formation of sulfuric acid (H2SO4) from dimethyl sulfide in the atmosphere. The new results can contribute to a better understanding of the atmospheric sulfur cycle," add the scientists responsible for global modelling, Dr Andreas Tilgner and Dr Erik Hoffmann.
As with many research findings, many new interesting questions arise here too: Once formed in the gas phase, sulfurous acid appears to have at least a certain stability. However, the lifetime with regard to the reaction with trace gases in the atmosphere is still completely unclear. The reaction with water vapour has also not yet been satisfactorily clarified. "Much more research is needed in further optimised experiments in order to sufficiently clarify the significance of H2SO3," adds Dr Torsten Berndt.
The detection of H2SO3 is another example of the discovery of new reaction pathways and the experimental proof of compounds that were previously only theoretically proposed or difficult to access. This is made possible by the interplay of optimised reaction control combined with highly sensitive detection methods. For example, a mass spectrometer with a detection limit of 104 molecules of a product per cubic centimetre at atmospheric pressure was used in this study, i.e. it is possible to detect a specific molecule in a mixture of 1015 molecules (1 quadrillion molecules). Ever-improving methods will allow an even deeper insight into reaction processes and thus contribute to an even better understanding of atmospheric chemistry and all other areas of chemistry.
Journal
Angewandte Chemie International Edition
Method of Research
Experimental study
Subject of Research
Not applicable
Article Title
Gas-Phase Formation of Sulfurous Acid (H2SO3) in the Atmosphere.
NASA's mini BurstCube mission detects mega blast
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BurstCube, trailed by another CubeSat named SNOOPI (Signals of Opportunity P-band Investigation), emerges from the International Space Station on April 18, 2024.
view moreCredit: NASA/Matthew Dominick
The shoebox-sized BurstCube satellite has observed its first gamma-ray burst, the most powerful kind of explosion in the universe, according to a recent analysis of observations collected over the last several months.
“We’re excited to collect science data,” said Sean Semper, BurstCube’s lead engineer at NASA’s Goddard Space Flight Center in Greenbelt, Maryland. “It’s an important milestone for the team and for the many early career engineers and scientists that have been part of the mission.”
The event, called GRB 240629A, occurred on June 29 in the southern constellation Microscopium. The team announced the discovery in a GCN (General Coordinates Network) circular on August 29.
BurstCube deployed into orbit April 18 from the International Space Station, following a March 21 launch.
The mission was designed to detect, locate, and study short gamma-ray bursts, brief flashes of high-energy light created when superdense objects like neutron stars collide. These collisions also produce heavy elements like gold and iodine, an essential ingredient for life as we know it.
BurstCube is the first CubeSat to use NASA’s TDRS (Tracking and Data Relay Satellite) system, a constellation of specialized communications spacecraft. Data relayed by TDRS (pronounced “tee-driss”) help coordinate rapid follow-up measurements by other observatories in space and on the ground through NASA’s GCN.
BurstCube also regularly beams data back to Earth using the Direct to Earth system — both it and TDRS are part of NASA’s Near Space Network.
After BurstCube deployed from the space station, the team discovered that one of the two solar panels failed to fully extend. It obscures the view of the mission’s star tracker, which hinders orienting the spacecraft in a way that minimizes drag. The team originally hoped to operate BurstCube for 12-18 months, but now estimates the increased drag will cause the satellite to re-enter the atmosphere in September.
“I’m proud of how the team responded to the situation and is making the best use of the time we have in orbit,” said Jeremy Perkins, BurstCube’s principal investigator at Goddard. “Small missions like BurstCube not only provide an opportunity to do great science and test new technologies, like our mission’s gamma-ray detector, but also important learning opportunities for the up-and-coming members of the astrophysics community.”
BurstCube is led by Goddard. It’s funded by the Science Mission Directorate’s Astrophysics Division at NASA Headquarters. The BurstCube collaboration includes: the University of Alabama in Huntsville; the University of Maryland, College Park; the Universities Space Research Association in Washington; the Naval Research Laboratory in Washington; and NASA’s Marshall Space Flight Center in Huntsville.
How bright is the universe’s glow? Study offers best measurement yet
University of Colorado at Boulder
Scientists have traveled to the edges of the solar system, virtually, at least, to capture the most accurate measurements to date of the faint glow that permeates the universe—a phenomenon known as the cosmic optical background.
The new study, published Aug. 28 in The Astrophysical Journal, draws on observations from NASA’s New Horizons spacecraft, which whizzed past Pluto in 2015 and is now nearly 5.5 billion miles from Earth. The research seeks to answer a deceptively simple question, said co-author Michael Shull, an astrophysicist at the University of Colorado Boulder.
“Is the sky really dark?” said Shull, professor emeritus in the Department of Astrophysical and Planetary Sciences.
Space may look black to human eyes, but scientists believe that it’s not completely dark. Since the dawn of the cosmos, trillions of galaxies containing countless stars have formed and died, leaving behind an imperceptibly faint light. Think of it as the night light in space.
Shull and the team, led by Marc Postman at the Space Telescope Science Institute in Baltimore, calculated just how bright that glow is. Their findings suggest that the cosmic optical background is roughly 100 billion times fainter than the sunlight that reaches Earth’s surface¬—far too faint for humans to see with the naked eye.
The results could help scientists shine a light on the history of the universe since the Big Bang.
“We’re kind of like cosmic accountants, adding up every source of light we can account for in the universe,” Shull said.
Into the dark
It’s a type of number crunching that has captured the imagination of scientists for nearly 50 years, he added.
Shull explained that, after decades of research, astrophysicists think they have a pretty good idea of how the cosmos evolved. The first galaxies formed during an epoch known as the Cosmic Dawn several hundred million years after the Big Bang. The starlight from galaxies in the distant universe reached its brightest point about 10 billion years ago and has been dimming ever since.
Precise measurements of the cosmic optical background could help scientists confirm whether this picture of the cosmos makes sense—or if there are mysterious, as-of-yet-undiscovered objects casting light into space.
Taking those kinds of measurements, however, isn’t easy, especially not from Earth.
Earth’s neighborhood is teeming with tiny grains of dust and other debris. Sunlight glints off this mess, washing out any signals that might be coming from the cosmic optical background.
“A metaphor I use is if you want to see the stars, you need to get out of Denver,” Shull said. “You have to go way out, right to the northeast corner of Colorado where all you have ahead of you are South Dakota and Nebraska.”
New Horizons has given scientists a once-in-a-lifetime opportunity to do something similar in space.
Cosmic accounting
The mission has uniquely Colorado origins. Alan Stern, who studied as a graduate student at CU Boulder under Shull and former Senior Research Associate Jack Brandt, leads the New Horizons mission. He’s currently based at the Southwest Research Institute in Boulder, Colorado. The spacecraft also carries the Student Dust Counter, an instrument designed and built by students at CU Boulder's Laboratory for Atmospheric and Space Physics (LASP).
Over the course of several weeks in summer 2023, the researchers pointed New Horizons’ Long Range Reconnaissance Imager (LORRI) at 25 patches of sky.
Even at the edge of the solar system, the team still had a lot of extra light to contend with. The Milky Way Galaxy, for example, sits within a halo that, like our solar system, gathers dust.
“You can’t get away from dust,” Shull said. “It’s everywhere.”
He and his colleagues estimated how much light that halo could generate, then subtracted it from what they were viewing with LORRI. After getting rid of additional sources of light, the team was left with the cosmic optical background.
In scientific terms, that background amounts to about 11 nanowatts per square meter per steradian. (A steradian is a patch of sky with a width about 130 times the diameter of the moon).
Shull said that this value lines up well with how many galaxies scientists believe should have formed since the Big Bang. Put differently, there don’t seem to be any strange objects, such as exotic kinds of particles, out there in space producing a lot of light. But the researchers can’t rule out such anomalies completely.
The team’s measurements are likely to be the best estimates of the universe’s glow for a long time. New Horizons is using its remaining fuel supplies to pursue other scientific priorities, and no other missions are currently heading toward those cold and dark corners of space.
“If they put a camera on a future mission, and we all wait a couple of decades for it to get out there, we could see a more exact measurement,” Shull said.
Other co-authors of the new study include SWRI’s Alan Stern and Tod Lauer at the U.S. National Science Foundation National Optical Infrared Astronomy Research Laboratory. Researchers from the Johns Hopkins University Applied Physics Laboratory, University of Texas at San Antonio and University of Virginia also participated.
Journal
The Astrophysical Journal
Article Title
New Synoptic Observations of the Cosmic Optical Background with New Horizons
Article Publication Date
28-Aug-2024
Representatives from NASA, ESA, JAXA, ASI, KASA meet during COSPAR 2024 to reinforce cooperation and coordination for future missions to the asteroid Apophis
Each agency representative presented the status of their current involvement in current and future planning for missions to Apophis (including extended mission for OSIRIS-REx, renamed OSIRIS-APEX, for NASA and the RAMSES mission for ESA) as well as the existing partnerships and mutual involvement in other agency’s missions, e.g. the infrared camera provided by JAXA in ESA’s mission Hera. Concepts to fly to Apophis, as well as reuse of existing payloads, spare parts and hardware, coordination of arrival time at Apophis of the different spacecraft, techniques to be demonstrated, science to be performed, and integration of scientific databases were also discussed during the meeting.
Although all risks of impacting the Earth have been ruled out for the April 2029 encounter, the asteroid Apophis will make its closest approach to Earth on Friday 13 April 2029, at an unprecedented distance. It will come closer to the Earth than the human-made geostationary satellites. It will even be visible to the naked eye speeding across the evening sky for an estimated 2 billion people spanning Western Europe and northern Africa. Apophis is one of the remnants of the bricks that formed planets and contain the record of the original composition of the solar nebula in which planets in our solar system formed. This once-per-7500-year opportunity to investigate the gravitational influence of the Earth on an asteroid should not be missed. Five years is short to develop and carry out the required investigations.
The agency representatives reaffirmed their strong desire to strengthen cooperation and coordination on such an important goal for humankind: both increasing our knowledge of the formation and history of the solar system and developing stronger capabilities in planetary defence.
The representatives stressed again the need for agencies to work jointly to prepare for this endeavour. This encounter offers a unique opportunity to inform the public at large about asteroids in particular and space research in general, and generate public outreach events and support material in the coming five years.
COSPAR is particularly proud to have been the initiator of this historic gathering, and stands ready to continue supporting this five-year effort as required.
Issued by COSPAR Communications:
Ms Leigh FERGUS-SWAN leigh.fergus@cosparhq.cnes.fr
Note to Editors
COSPAR, the largest international scientific society dedicated to promoting global cooperation in space research, was established in 1958. It serves as a neutral platform for scientific dialogue among scientists from around the world. Today, COSPAR comprises 46 national scientific institutions and 13 international scientific unions, with 13,000 space scientists actively participating in its activities, including attending assemblies, contributing to panels and roadmaps, and publishing in its journals.
COSPAR’s core mission is to facilitate dialogue and encourage international collaboration among space stakeholders across the globe. It operates through scientific commissions, panels and task groups that encompass all disciplines of space science, from Earth and atmospheric sciences to planetary science, astrophysics, solar and space plasma physics, and life and microgravity sciences.
A recent focus has been on strengthening ties between science and industry. This was achieved by forming the Committee on Industry Relations, which includes 18 leading aerospace companies worldwide. The Committee advises COSPAR on integrating industry capabilities into its activities, ensuring mutual benefits for both science and industry.
About NASA
NASA explores the unknown in air and space, innovates for the benefit of humanity, and inspires the world through discovery. For more than 65 years, NASA has made the seemingly impossible, possible. At its 20 centers and facilities across the country and with U.S. commercial companies and international partners, NASA leads studying Earth science, including climate, our Sun, solar system, and the larger universe. NASA conducts cutting-edge research to advance technology and aeronautics. NASA operates the world’s leading space laboratory, the International Space Station, and plans to establish a sustainable and strong exploration presence on the Moon this decade through the Artemis campaign. In 2016, NASA established the Planetary Defense Coordination Office (PDCO) to manage the agency's ongoing mission of finding, tracking, and better understanding asteroids and comets that could pose an impact hazard to Earth. PDCO leads activities for protecting Earth from Near Earth Object impacts.
About ESA
The European Space Agency (ESA) provides Europe’s gateway to space. ESA is an intergovernmental organisation, created in 1975, with the mission to shape the development of Europe’s space capability and ensure that investment in space delivers benefits to the citizens of Europe and the world. ESA has 22 Member States: Austria, Belgium, the Czech Republic, Denmark, Estonia, Finland, France, Germany, Greece, Hungary, Ireland, Italy, Luxembourg, the Netherlands, Norway, Poland, Portugal, Romania, Spain, Sweden, Switzerland and the United Kingdom. Latvia, Lithuania, Slovakia and Slovenia are Associate Members. ESA has established formal cooperation with four Member States of the EU. Canada takes part in some ESA programmes under a Cooperation Agreement. By coordinating the financial and intellectual resources of its members, ESA can undertake programmes and activities far beyond the scope of any single European country. It is working in particular with the EU on implementing the Galileo and Copernicus programmes as well as with Eumetsat for the development of meteorological missions.
About JAXA
The Japan Aerospace Exploration Agency (JAXA), was established as an Independent Administrative Agency in 2003, merging three aerospace organizations, the Institute of Space and Astronautical Science, the National Aerospace Laboratory, and the National Space Development Agency of Japan. JAXA is now positioned as a “National Research and Development Agency” as well as a “Core Implementing Agency” to support the Japanese Government in aerospace activities. JAXA has conducted asteroid explorations including Hayabusa and Hayabusa2 and provided the infrared camera in ESA’s mission Hera. The Agency executes ground observation including asteroids from Bisei Spaceguard Center.
About ASI
The Italian Space Agency (ASI) was established in 1988 with the task of preparing and implementing the Italian space policy in accordance with the Government guidelines. ASI is recognized as one of the most important global stakeholders in all space domains from human and robotic exploration to space science, propulsion, earth observation, navigation and telecommunications, thanks to and a continuous cooperation with the scientific community and Italian manufacturers and to fruitful international collaborations. The Agency coordinates the Italian participation in the European Space Agency (ESA), where Italy is the third largest contributor, and in the European Union programs and maintains international relations with numerous space partners and international organizations.
About KASA
The Korea AeroSpace Administration (KASA) was established on 27th May 2024, and announced its policy directions on 30th May, including asteroid exploration as one of the highest priorities. KASA is responsible for developing the national space strategy, implementing research and development projects, supporting the aerospace sector and promoting international cooperation.
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