Using the European Southern Observatory’s Very Large Telescope (ESO’s VLT) in Chile, astronomers have imaged 42 of the largest objects in the asteroid belt, located between Mars and Jupiter. Never before had such a large group of asteroids been imaged so sharply. The observations reveal a wide range of peculiar shapes, from spherical to dog-bone, and are helping astronomers trace the origins of the asteroids in our Solar System.
The detailed images of these 42 objects are a leap forward in exploring asteroids, made possible thanks to ground-based telescopes, and contribute to answering the ultimate question of life, the Universe, and everything .
“Only three large main belt asteroids, Ceres, Vesta and Lutetia, have been imaged with a high level of detail so far, as they were visited by the space missions Dawn and Rosetta of NASA and the European Space Agency, respectively,”
explains Pierre Vernazza, from the Laboratoire d’Astrophysique de Marseille in France, who led the asteroid study published today in Astronomy & Astrophysics.
“Our ESO observations have provided sharp images for many more targets, 42 in total.”
The previously small number of detailed observations of asteroids meant that, until now, key characteristics such as their 3D shape or density had remained largely unknown. Between 2017 and 2019, Vernazza and his team set out to fill this gap by conducting a thorough survey of the major bodies in the asteroid belt.
Most of the 42 objects in their sample are larger than 100 km in size; in particular, the team imaged nearly all of the belt asteroids larger than 200 kilometres, 20 out of 23. The two biggest objects the team probed were Ceres and Vesta, which are around 940 and 520 kilometres in diameter, whereas the two smallest asteroids are Urania and Ausonia, each only about 90 kilometres.
By reconstructing the objects’ shapes, the team realised that the observed asteroids are mainly divided into two families. Some are almost perfectly spherical, such as Hygiea and Ceres, while others have a more peculiar, “elongated” shape, their undisputed queen being the “dog-bone” asteroid Kleopatra.
By combining the asteroids’ shapes with information on their masses, the team found that the densities change significantly across the sample. The four least dense asteroids studied, including Lamberta and Sylvia, have densities of about 1.3 grams per cubic centimetre, approximately the density of coal. The highest, Psyche and Kalliope, have densities of 3.9 and 4.4 grammes per cubic centimetre, respectively, which is higher than the density of diamond (3.5 grammes per cubic centimetre).
This large difference in density suggests the asteroids’ composition varies significantly, giving astronomers important clues about their origin.
“Our observations provide strong support for substantial migration of these bodies since their formation. In short, such tremendous variety in their composition can only be understood if the bodies originated across distinct regions in the Solar System,”
explains Josef Hanuš of the Charles University, Prague, Czech Republic, one of the authors of the study. In particular, the results support the theory that the least dense asteroids formed in the remote regions beyond the orbit of Neptune and migrated to their current location.
These findings were made possible thanks to the sensitivity of the Spectro-Polarimetric High-contrast Exoplanet REsearch (SPHERE) instrument mounted on ESO’s VLT.
“With the improved capabilities of SPHERE, along with the fact that little was known regarding the shape of the largest main belt asteroids, we were able to make substantial progress in this field,”
says co-author Laurent Jorda, also of the Laboratoire d’Astrophysique de Marseille.
Astronomers will be able to image even more asteroids in fine detail with ESO’s upcoming Extremely Large Telescope (ELT), currently under construction in Chile and set to start operations later this decade.
“ELT observations of main-belt asteroids will allow us to study objects with diameters down to 35 to 80 kilometres, depending on their location in the belt, and craters down to approximately 10 to 25 kilometres in size,”
“Having a SPHERE-like instrument at the ELT would even allow us to image a similar sample of objects in the distant Kuiper Belt. This means we’ll be able to characterise the geological history of a much larger sample of small bodies from the ground.”
 In The Hitchhiker’s Guide to the Galaxy by Douglas Adams, the number 42 is the answer to the “Ultimate Question of Life, the Universe, and Everything.” Today, 12 October 2021, is the 42nd anniversary of the publication of the book.
 All observations were conducted with the Zurich IMaging POLarimeter (ZIMPOL), an imaging polarimeter subsystem of the SPHERE instrument that operates at visible wavelengths.
Asteroid Day is held on 30 June each year to mark the date of Earth’s largest asteroid impact in recorded history, the Siberia Tunguska event. Asteroid Day was co-founded by astrophysicist and famed musician Dr Brian May of the rock group QUEEN, Apollo 9 astronaut Rusty Schweickart, filmmaker Grig Richters, and B612 Foundation President Danica Remy, to educate the public about the importance of asteroids in our history and the role they play in the solar system. In 2016, with the leadership of the Association of Space Explorers (ASE), the United Nations declared Asteroid Day to be a global day of education to raise awareness and promote knowledge in the general public about asteroids. Major events in past years have taken place in London, San Francisco, Washington, DC, Tanzania, Milan and Rimini, Italy; Garching, Germany; and Rio de Janeiro, Brazil; in addition to thousands of events worldwide.
This year, the event is a fully digital celebration of asteroid science and exploration. Panel discussions and one-on-one interviews with astronauts and world experts will be broadcast on 30 June 2020.
Each year Asteroid Day presents the public with a snap-shot of cutting-edge asteroid research from the largest telescopes on Earth to some of the most ambitious space missions. Topics of discussion this year include the acceleration in the rate of our asteroid discoveries and why it is set to accelerate even faster, the imminent arrival of samples from asteroid Ryugu and Bennu, the exciting preparations for the joint US-Europe mission to binary asteroid Didymos, and much more.
Asteroids are the leftover remnants of the birth of the planets in the Solar System, and many are the shattered fragments of these diminutive proto-planets that never made it to maturity. “Asteroid exploration missions tell us about the birth of our own planet and reveal how asteroids can serve astronauts as stepping stones to Mars,” says Tom Jones, PhD, veteran astronaut and planetary scientist, and Asteroid Day Expert Panel member.
Each asteroid is an individual with its own story to tell. And that’s what Asteroid Day is all about: bringing those stories to the widest audience possible. “Space and science have been an endless source of inspiration for SES! This is one of the reasons why we and our partners continue to do extraordinary things in space to deliver amazing experiences everywhere on earth,” says Ruy Pinto, Chief Technology Officer at SES. “Through satellite broadcasting, we are able to reach millions of TV households and this enables us to unite people around science, space, and technology topics.”
“The valuable expertise of SES and BCE play a central role in making Asteroid Day an international success and enabling us to have a global conversation about space, space resources, and asteroids in these COVID-19 times.” says Mark Serres, the CEO of the Luxembourg Space Agency.
A highlight of this year’s events will be the official premier of the documentary Apollo 9 & Beyond (at Vimeo.com), which profiles Apollo 9 astronaut Rusty Schweickart, who has been a leader in efforts to deal with the threat of asteroid impacts on Earth:
In this profoundly beautiful and moving film, Apollo 9 Astronaut Rusty Schweickart discusses the Apollo 9 mission, his life-altering spacewalk, and our cosmic birth. Rusty describes testing the Lunar Module, the first true spaceship that would four month later land men on the moon, his historic spacewalk, the first EVA of the Apollo era, and the incredible beauty of the Earth from space.
Beyond the Apollo 9 mission itself, Rusty goes much deeper to explore the philosophical and evolutionary implications of humanity’s first steps into the cosmos, describing the powerful effects of his “five minutes” alone on the Lunar Module porch as he observed the Earth below and pondered the big questions of existence – questions he would come to answer back on Earth.
NASA’s Perseverance Mars rover is just over a month from its July 20 targeted launch date. The rover’s astrobiology mission will seek signs of past microscopic life on Mars, explore the geology of the Jezero Crater landing site, and demonstrate key technologies to help prepare for future robotic and human exploration. And the rover will do all that while collecting the first samples of Martian rock and regolith (broken rock and dust) for return to Earth by a set of future missions.
This video describes the efforts to keep the project on track during the coronavirus pandemic:
Getting a Mars rover built, tested and to the launch pad is a feat that requires the dedication of hundreds of team members. The team behind NASA’s Perseverance Mars rover faced one of its biggest challenges when the coronavirus pandemic struck during a crucial time before launch. The safety of the team members became top priority yet they rose to the challenge of completing the rover on time for its launch date, either by working remotely or under new “safe at work” procedures. They developed an increased appreciation for the name of the rover and in May they created the COVID-19 Perseverance Plate, which is now mounted on the side of the rover. The plate commemorates all those impacted by the pandemic and pays special tribute to front line health care workers. Perseverance is targeted to launch from Cape Canaveral, Florida, on July 20, 2020. It will land on Mars on February 18, 2021.
China plans to launch its first Mars exploration mission Tianwen-1 between July and August, Bao Weimin, academician of Chinese Academy of Sciences and director of the Science and Technology Commission at the China Aerospace Science and Technology Corporation, has told CCTV while sharing details about the mission.
According to the plan, the Mars probe will release a rover after a soft landing on the planet and the rover will stay on Mars for 90 Mars sols, or days, on a variety of missions, including reconnaissance and exploration of the Martian landscape.
** Check out the Planetary Society’s Mars map showing every landing attempt, including both successes and failures:
** Latest on efforts to help Insight’s thermometer dig into the Martian surface. The Insight lander set down on the Martian surface on Nov. 26, 2018. A seismometer was set on the ground soon after and has worked well. The HP3 temperature probe was to dig several meters into the ground and measure the temperature. It has not been as successful. The probe’s digging mechanism failed to get a grip in the loose soil in the upper level of the ground and reached less than a meter down The Insight team subsequently came up with a plan to use the lander’s robotic arm to push on the probe until it reached firmer material and could then dig on its own. The
In May there was practically no sunspot activity. As the month began, a sunspot faded away, and then, just as the month ended, a sunspot began to appear. Both sunspots had polarities that assign them to the coming solar maximum. Both (as have other new cycle sunspots over the past year) suggest that we will have a solar maximum in the coming five years, not a grand minimum with no sunspots for decades.
The lack of sunspots for the entire month, however, also suggests that the ongoing minimum will be the deepest in centuries. In fact, the number of days where the Sun’s visible hemisphere was blank both last year and this year remains the highest in two centuries. This lack of sunspots also strengthens the possibility that the next maximum will also be the weakest in two centuries.
Xplore Founder and Chief Operating Officer, Lisa Rich said, “We are pleased to announce NOAA has awarded Xplore a study to evaluate the feasibility of a commercial Lagrange point mission with our Xcraft spacecraft. We welcome the potential future opportunity to provide commercial services that can be leveraged to better understand the Sun and provide advanced warning to protect our critical infrastructure.” She continued, “Xplore’s unique, Space as a Service business model provides a cost-effective solution enabling organizations like NOAA to purchase just the data they need via service agreements without having to buy the whole system. Our award further confirms NOAA’s commitment to leverage new commercial services to provide the environmental data needed for understanding the weather here on Earth and in space.”
The Earth-Sun L1 Lagrange point is located approximately a million miles (1.6 million km) from the Earth toward the Sun and three times farther than the Moon – quite the distance when compared to the International Space Station, which is merely 254 miles away. Xplore’s multi-mission ESPA-class space vehicle, the Xcraft™ is designed for missions beyond Earth orbit that include the Moon, Mars, Venus, near-Earth asteroids and Lagrange points, the focus of Xplore’s NOAA mission study.
ESA’s Sun-exploring mission Solar Orbiter has made its first close approach to the star on June 15, getting as close as 77 million kilometres to its surface, about half the distance between the Sun and Earth.
In the week following this first perihelion, the point in the orbit closest to the Sun, the mission scientists will test the spacecraft’s ten science instruments, including the six telescopes on-board, which will acquire close-up images of the Sun in unison for the first time. According to ESA’s Solar Orbiter Project Scientist Daniel Müller, the images, to be released in mid-July, will be the closest images of the Sun ever captured.
“We have never taken pictures of the Sun from a closer distance than this,” Daniel says. “There have been higher resolution close-ups, e.g. taken by the four-meter Daniel K. Inouye Solar Telescope in Hawaii earlier this year. But from Earth, with the atmosphere between the telescope and the Sun, you can only see a small part of the solar spectrum that you can see from space.”
NASA’s Parker Solar Probe, launched in 2018, makes closer approaches. The spacecraft, however, doesn’t carry telescopes capable of looking directly at the Sun.
“Our ultraviolet imaging telescopes have the same spatial resolution as those of NASA’s Solar Dynamic Observatory (SDO), which takes high-resolution images of the Sun from an orbit close to Earth. Because we are currently at half the distance to the Sun, our images have twice SDO’s resolution during this perihelion,” says Daniel.
** The Chinese lander Chang’e 4 and the lander Yutu-2 awoke on June 15th after another lunar night and are back at work investigating the Moon’s farside. This is the 19th lunar day since the mission landed on January 3, 2019 in the Von Karman Crater located in the South Pole-Aitken Basin.
After a long hiatus, the China National Space Administration in 2013 finally returned telescopes to the Moon. But this time, no astronauts were required. This first-ever remotely controlled lunar telescope was an add-on instrument that flew with the Chang’e-3 lander.
At just 6 inches in diameter, the Lunar-based Ultraviolet Telescope (LUT) is a far cry from the kinds of instruments astronomers have long dreamed about sending to the Moon. But even at that size, the wavelengths LUT observes can offer unique insights into the cosmos, all without interference from Earth.
Chinese scientists used LUT to collect thousands of hours’ worth of data, tracking stars and even galaxies. And, perhaps more importantly, the telescope’s stable performance also served as a technology demonstration for future missions.
Chinese scientists have since used the telescope to carry out studies of the universe viewed through previously unexplored radio wavelengths. However, due to the modest abilities of the instrument, their observations are limited to the relatively nearby cosmos.
Citizen science pioneers recently made two contributions to a better knowledge of outer space. Backyard astronomers of the SETI Institute and Unistellar network conducted in April citizen science observations, and their discoveries will improve our understanding of asteroids and exoplanets. Thanks to their work, we know precisely the location of the main-belt asteroid 2000 UD52 and have confirmed an exoplanet transit of Qatar-1b.
** Asteroids and Comets
** What are rubble pile asteroids with SETI Institute scientist, Michael Busch. – SETI Institute
Bennu is considered a potentially dangerous asteroid. Its orbit is such at there is a very tiny chance (less than 1 in 2,700) that it will hit the Earth late in the next century. What OSIRIS-REx has shown us, however, is that though the asteroid is 1,600 feet across with a mass of about 85 million tons, if it should cross paths with the Earth a large percentage of it, possibly almost all, will break apart and burn up in the atmosphere before hitting the ground.
At the same time, we know as yet little about the asteroid’s interior. While present data suggests the asteroid is 20 to 40 percent empty space, there still could be buried beneath its gravel pile surface much larger structurally sound pieces that could barrel their way through the atmosphere and smash into the ground.
To find out, we need to learn how to safely and accurately map its interior. Only then will we know if Bennu is truly a threat, or simply a vehicle for providing some future generation on Earth a truly spectacular fireworks show.
** What to do about asteroid threats. A panel discussion at the SETI Institute:
Could an asteroid strike our planet in the future? Astronomers think so since thousands of near-earth asteroids (NEAs) cross our planet’s path. However, the good news is that an asteroid impact is a preventable large-scale disaster. NASA has recently opened a Planetary Defense Coordination Office to manage its ongoing mission of so-called “Planetary Defense.” One of the programs is to find, track, and characterize at least 90 percent of the predicted number of NEAs that are at least 140 meters — bigger than a small football stadium — and characterize a subset of them, so we develop projects to deflect them if needed. How are NEAs found and tracked? What are the expected NEA close approaches?
Researchers from the University of Geneva, have confirmed the existence of the Proxima b extrasolar planet using measurements from the Swiss-built ESPRESSO spectrograph.
The existence of a planet the size of Earth around the closest star in the solar system, Proxima Centauri, has been confirmed by an international team of scientists including researchers from the University of Geneva (UNIGE). The results, which you can read all about in the journal Astronomy & Astrophysics, reveal that the planet in question, Proxima b, has a mass of 1.17 earth masses and is located in the habitable zone of its star, which it orbits in 11.2 days.
This breakthrough has been possible thanks to radial velocity measurements of unprecedented precision using ESPRESSO, the Swiss-manufactured spectrograph – the most accurate currently in operation – which is installed on the Very Large Telescope in Chile. Proxima b was first detected four years ago by means of an older spectrograph, HARPS – also developed by the Geneva-based team – which measured a low disturbance in the star’s speed, suggesting the presence of a companion
The planet, however, appears to offer a very challenging environment for life to arise:
Although Proxima b is about 20 times closer to its star than the Earth is to the Sun, it receives comparable energy, so that its surface temperature could mean that water (if there is any) is in liquid form in places and might, therefore, harbour life.
Having said that, although Proxima b is an ideal candidate for biomarker research, there is still a long way to go before we can suggest that life has been able to develop on its surface. In fact, the Proxima star is an active red dwarf that bombards its planet with X rays, receiving about 400 times more than the Earth.
“Is there an atmosphere that protects the planet from these deadly rays?” asks Christophe Lovis, a researcher in UNIGE’s Astronomy Department and responsible for ESPRESSO’s scientific performance and data processing.
“And if this atmosphere exists, does it contain the chemical elements that promote the development of life (oxygen, for example)? How long have these favourable conditions existed? We’re going to tackle all these questions, especially with the help of future instruments like the RISTRETTO spectrometer, which we’re going to build specially to detect the light emitted by Proxima b, and HIRES, which will be installed on the future ELT 39 m giant telescope that the European Southern Observatory (ESO) is building in Chile.”
There may be a second small planet as well:
In the meantime, the precision of the measurements made by ESPRESSO could result in another surprise. The team has found evidence of a second signal in the data, without being able to establish the definitive cause behind it.
“If the signal was planetary in origin, this potential other planet accompanying Proxima b would have a mass less than one third of the mass of the Earth. It would then be the smallest planet ever measured using the radial velocity method”, adds Professor Pepe.
** CHEOPS (Characterizing Exoplanet Satellite) is a smallsat launched last December to study exoplanets. The mission is part of a EU program to fund science missions at a lower cost that then traditional big . The
CHEOPS has reached its next milestone: Following extensive tests in Earth’s orbit, some of which the mission team was forced to carry out from home due to the coronavirus crisis, the space telescope has been declared ready for science. CHEOPS stands for “CHaracterising ExOPlanet Satellite”, and has the purpose of investigating known exoplanets to determine, among other things, whether they have conditions that are hospitable to life.
CHEOPS is a joint mission by the European Space Agency (ESA) and Switzerland, under the leadership of the University of Bern in collaboration with the University of Geneva (UNIGE). After almost three months of extensive testing, with part of it in the midst of the lockdown to contain the coronavirus, on Wednesday, March 25, 2020, ESA declared the CHEOPS space telescope ready for science. With this achievement, ESA has handed over the responsibility to operate CHEOPS to the mission consortium, which consists of scientists and engineers from approximately 30 institutions in 11 European countries.
For this testing period, the team chose
the planetary system HD 93396 which is in the Sextans constellation, some 320 light years away from Earth. This system consists of a giant exoplanet called KELT-11b, which was discovered in 2016 to orbit this star in 4.7 days. The star is almost three times the size of the sun.
The team chose this particular system because the star is so big that the planet takes a long time to pass in front of it: in fact, almost eight hours. “This gave CHEOPS the opportunity to demonstrate its ability to capture long transit events otherwise difficult to observe from the ground, as the ‘astronomical’ part of the night for ground-based astronomy usually takes less than eight hours,” explains Didier Queloz, professor at the Astronomy Department of the Faculty of Science at the University of Geneva and spokesperson of the CHEOPS Science Team. The first transit light curve of CHEOPS is shown in Figure 3, where the dip due to the planet occurs approximately nine hours after the he beginning of the observation
The transit of KELT-11b measured by CHEOPS enabled determining the size of the exoplanet. It has a diameter of 181,600 km, which CHEOPS is able to measure with an accuracy of 4’290 km. The diameter of the Earth, in comparison, is only approximately 12,700 km, while that of Jupiter – the biggest planet in our solar system – is 139,900 km. Exoplanet KELT-11b is therefore bigger than Jupiter, but its mass is five times lower, which means it has an extremely low density: “It would float on water in a big-enough swimming pool,” says David Ehrenreich, CHEOPS Mission Scientist from the University of Geneva. The limited density is attributed to the close proximity of the planet to its star. Figure 4 shows a drawing of the first transit planet system to be successfully observed by CHEOPS.
Benz explains that the measurements by CHEOPS are five times more accurate than those from Earth. “That gives us a foretaste for what we can achieve with CHEOPS over the months and years to come,” continues Benz.
Nanoracks’ 17th CubeSat deployment mission included satellites launched to the International Space Station on both Northrop Grumman’s NG-12 flight and the SpaceX CRS-19 mission. The deployer packs were then assembled together on orbit by the astronaut crew.
“The diversity of users on each CubeSat mission is growing with every flight,” says Nanoracks Senior External Payloads Mission Manager, Tristan Prejean. “Our 17th CubeSat mission has satellites built by university students, international space agencies and research institutes, commercial companies reaching the ISS for the first time, and by our friends at NASA. Commercial access to low-Earth orbit is enabling an unprecedented cohort of users from around the world to make discoveries in space – and we are watching this grow year by year.”
Notably, AzTechSat-1 is the first satellite built by students in Mexico for deployment from the Space Station and is the first CubeSat built as a collaboration between the Mexican Space Agency and NASA. The investigation demonstrates communication within a satellite network in low-Earth orbit. Such Intra-satellite communication could reduce the need for ground stations, lowering the cost and increasing the number of data downloads possible for satellite applications.
Additionally, HARP marked the 100th CubeSat project for which launch and deployment was funded by NASA’s CubeSat Launch Initiative (CSLI), which offers universities, high schools and non-profit organizations the opportunity to fly small satellites. Launches for CSLI selectees are provided through Educational Launch of Nanosatellites (ELaNa) missions facilitated by NASA’s Launch Services Program (LSP). HARP, RadSat-u, Phoenix, SOCRATES, CryoCube, AzTechSat-1, SORTIE, and ARGUS-02 missions were all part of the ELaNa 25 mission managed by NASA LSP.
Today the Hyper-Angular Rainbow Polarimeter (HARP) CubeSat made history by becoming the 100th CubeSat Launch Initiative (CSLI) selected mission deployed into space. This mission marks nearly 12 years of the CSLI providing CubeSat developers rideshare opportunities to space via Educational Launch of Nanosatellites (ELaNa) missions.
“This 100th mission is extremely noteworthy because it highlights just how special and valuable CSLI is. Not only does the initiative provide real-life, hands-on experience to the next generation of space exploration professionals, it also adds tremendous value and moves NASA’s mission forward in meaningful ways,” said Jim Norman, director, Launch Services at NASA Headquarters in Washington. “I want to thank all the university students, faculty and staff, industry partners and NASA centers who have participated in this program for their contributions.”
HARP is a 3U CubeSat designed to measure the microphysical properties of atmospheric aerosols, cloud water and ice particles. It is a precursor for a new generation of imaging polarimeters to be used for the detailed measurements of aerosol and cloud properties in larger missions. The wide field-of-view imager splits three spatially identical images into three independent polarizer and detector arrays. This technique achieves simultaneous imagery of the three polarization states and is the key innovation to achieve a high polarimetric accuracy with no moving parts. The mission is expected to spend nearly a year in orbit with three months dedicated to technology demonstrations and an extended science data period of an additional seven months.
Funded by NASA’s Earth Science Technology Office, HARP launched Nov. 2, 2019, as part of the ELaNa 25 mission on Northrup Grumman’s 12th Commercial Resupply Services mission to the International Space Station.
Space BD Inc is the official service provider selected by JAXA in the area of ISS utilisation and satellite launch service.
Curtin University has been planning and developing the satellites named Binar-1 (1U CubeSat) and Binar-2 (3U CubeSat) since 2018. These satellites will be the first pair of satellites launched from Curtin University as well as the first from Western Australia.
The project is led by Professor Phil Bland at the Space Science and Technology Centre at Curtin University. Professor Bland, along with a team of 12 Curtin staff and student engineers have developed the miniaturised satellites.
Phosphorus, present in our DNA and cell membranes, is an essential element for life as we know it. But how it arrived on the early Earth is something of a mystery. Astronomers have now traced the journey of phosphorus from star-forming regions to comets using the combined powers of ALMA and the European Space Agency’s probe Rosetta. Their research shows, for the first time, where molecules containing phosphorus form, how this element is carried in comets, and how a particular molecule may have played a crucial role in starting life on our planet.
“Life appeared on Earth about 4 billion years ago, but we still do not know the processes that made it possible,“
says Víctor Rivilla, the lead author of a new study published today in the journal Monthly Notices of the Royal Astronomical Society. The new results from the Atacama Large Millimeter/Submillimeter Array (ALMA), in which the European Southern Observatory (ESO) is a partner, and from the ROSINA instrument on board Rosetta, show that phosphorus monoxide is a key piece in the origin-of-life puzzle.
With the power of ALMA, which allowed a detailed look into the star-forming region AFGL 5142, astronomers could pinpoint where phosphorus-bearing molecules, like phosphorus monoxide, form. New stars and planetary systems arise in cloud-like regions of gas and dust in between stars, making these interstellar clouds the ideal places to start the search for life’s building blocks.
The ALMA observations showed that phosphorus-bearing molecules are created as massive stars are formed. Flows of gas from young massive stars open up cavities in interstellar clouds. Molecules containing phosphorus form on the cavity walls, through the combined action of shocks and radiation from the infant star. The astronomers have also shown that phosphorus monoxide is the most abundant phosphorus-bearing molecule in the cavity walls.
After searching for this molecule in star-forming regions with ALMA, the European team moved on to a Solar System object: the now-famous comet 67P/Churyumov–Gerasimenko. The idea was to follow the trail of these phosphorus-bearing compounds. If the cavity walls collapse to form a star, particularly a less-massive one like the Sun, phosphorus monoxide can freeze out and get trapped in the icy dust grains that remain around the new star. Even before the star is fully formed, those dust grains come together to form pebbles, rocks and ultimately comets, which become transporters of phosphorus monoxide.
ROSINA, which stands for Rosetta Orbiter Spectrometer for Ion and Neutral Analysis, collected data from 67P for two years as Rosetta orbited the comet. Astronomers had found hints of phosphorus in the ROSINA data before, but they did not know what molecule had carried it there. Kathrin Altwegg, the Principal Investigator for Rosina and an author in the new study, got a clue about what this molecule could be after being approached at a conference by an astronomer studying star-forming regions with ALMA:
“She said that phosphorus monoxide would be a very likely candidate, so I went back to our data and there it was!”
This first sighting of phosphorus monoxide on a comet helps astronomers draw a connection between star-forming regions, where the molecule is created, all the way to Earth.
“The combination of the ALMA and ROSINA data has revealed a sort of chemical thread during the whole process of star formation, in which phosphorus monoxide plays the dominant role,”
says Rivilla, who is a researcher at the Arcetri Astrophysical Observatory of INAF, Italy’s National Institute for Astrophysics.
“Phosphorus is essential for life as we know it,” adds Altwegg. “As comets most probably delivered large amounts of organic compounds to the Earth, the phosphorus monoxide found in comet 67P may strengthen the link between comets and life on Earth.”
This intriguing journey could be documented because of the collaborative efforts between astronomers.
“The detection of phosphorus monoxide was clearly thanks to an interdisciplinary exchange between telescopes on Earth and instruments in space,”
Leonardo Testi, ESO astronomer and ALMA European Operations Manager, concludes:
“Understanding our cosmic origins, including how common the chemical conditions favourable for the emergence of life are, is a major topic of modern astrophysics. While ESO and ALMA focus on the observations of molecules in distant young planetary systems, the direct exploration of the chemical inventory within our Solar System is made possible by ESA missions, like Rosetta. The synergy between world leading ground-based and space facilities, through the collaboration between ESO and ESA, is a powerful asset for European researchers and enables transformational discoveries like the one reported in this paper.”