Astronomers have revealed the first image of the black hole at the centre of our galaxy, the Milky Way. The image was produced by the Event Horizon Telescope (EHT) Collaboration, an international team made up of over 300 scientists on five continents – including Africa.
Black holes were predicted by Albert Einstein’s General Theory of Relativity over a century ago. They are regions of space so dense that nothing, including light, can escape. Their boundary is known as the event horizon, which marks the point of no return. That’s just one of the reasons these objects are hidden from our eyes. The other is that they are exceedingly small, when placed in their cosmic context. If our Milky Way galaxy were the size of a soccer field, its black hole event horizon would be a million times smaller than a pin prick at centrefield.
How, then, can one photograph them? Our team did so by capturing light from the hot swirling gas in the immediate vicinity of the black hole. This light, with a wavelength of 1 millimetre, is recorded by a global network of antennas that form a single, Earth-sized virtual telescope.
The light looks rather like a ring, a characteristic signature that is the direct consequence of two key processes. First, the black hole is so dense that it bends the path of light near it. Second, it captures light that strays too close to the event horizon. The combined effect produces a so-called black hole shadow – a brightened ring surrounding a distinct deficit of light centred on the black hole. In the case of our Milky Way black hole, this ring has the apparent size of a doughnut on the moon, requiring an extraordinary engineering effort to bring it into focus.
The unveiling of an image of our black hole, Sagittarius A*, is not just a massive moment for science. It could also be an important catalyst for diversifying African astrophysics research using existing strengths. We were the only two of more than 300 EHT team members based on the African continent. The continent doesn’t host any EHT telescopes – we were brought on board because of expertise we’ve developed in preparation for the world’s largest radio telescope, the Square Kilometre Array (SKA), to be co-hosted by South Africa and Australia.
Why the image is important
This is not the first time a black hole image has captured people’s attention. We were also members of the team that captured the first ever image of a black hole in 2019 (this one is at the centre of a different galaxy, Messier 87, which is 55 million light years away). It has been estimated that more than 4.5 billion people saw that image. Sagittarius A* has also dominated headlines and captured people’s imaginations.
But there’s more to this result than just an incredible image. A plethora of rich scientific results has been described in ten publications by the team. Here are three of our primary highlights.
First, the image is a remarkable validation of Einstein’s General Theory of Relativity. The EHT has now imaged two black holes with masses that differ by a factor of over 1000. Despite the dramatic difference in mass, the measured size and shape are consistent with theoretical predictions.
Second, we have now imaged black holes with very different environments. A wealth of prior research over the past two or three decades shows strong empirical evidence that galaxies and their black holes co-evolve over cosmic time, despite their completely disparate sizes. By zooming into the event horizon of black holes in giant galaxies like M87, as well as more typical galaxies like our own Milky Way, we learn more about how this seemingly implausible relationship between the black hole and its host galaxy plays out.
Third, the image provides us with new insights on the central black hole in our own galactic home. It is the nearest such beast to Earth, so it provides a unique laboratory to understand this interplay – not unlike scrutinising a tree in your own garden to better understand the forests on the distant horizon.
Southern Africa’s geographic advantage
We are proud to be part of the team that produced the first black hole images. In future, we believe South Africa, and the African continent more broadly (including a joint Dutch-Namibian initiative), could play a critical role in making the first black hole movies.
As has been the case with the country’s key role in paleoanthropology, there are contributions to global astronomy that can only be made from South African soil. Sagittarius A* lies in the southern sky, passing directly above South Africa. That is a major reason why this image of the Milky Way’s centre, taken by the MeerKAT (a precursor to the SKA) is the best there is.
South Africa also has well-established infrastructure at its astronomical sites, which are protected by legislation. And it has world-class engineers at the forefront of their craft. This makes for low-cost, high-performance telescopes delivered on time and to budget.
New technology is also on our side: a cutting-edge simultaneous multi-frequency receiver design, pioneered by our Korean colleagues, means that EHT sites no longer need to be the most pristine, high-altitude locations on Earth.
All the elements are in place for a dramatic increase in the number of young Africans who participate in this new era of black hole imaging and precision tests of gravity. In the coming years, we hope to be writing about findings that couldn’t have been made without technology on South African soil, as well as African scientists leading high-impact, high-visibility EHT science in synergy with our multi-wavelength astronomy and high-energy astrophysics programmes.
James Bardeen, an expert in solving Einstein's equations, has died at the age of 83 – electriccitymagazine.ca
James Bardeen, who helped elucidate the properties and behavior of black holes, paving the way for what has been called the golden age of black hole astrophysics, died on June 20 in Seattle. He was 83 years old.
His son William said the cause was cancer. Dr. Bardeen, professor emeritus of physics at the University of Washington, was living in a nursing home in Seattle.
Dr. Bardeen was a descendant of a famous family of physicists. His father is John Twice won the Nobel Prize in Physics, for the invention of the transistor and the theory of superconductivity; his brother, Williaman expert in quantum theory at the Fermi National Accelerator Laboratory in Illinois.
Dr. Bardeen was an expert in solving equations of Einstein’s general theory of relativity. This theory attributes what we call gravity to the curvature of spacetime with matter and energy. Its most mysterious and disturbing consequence has been the possibility of black holes, places so dense that they become endless one-way exit ramps from the universe, swallowing even light and time.
Dr. Bardeen will find the work of his life investigating those mysteries, as well as related mysteries about the evolution of the universe.
said Michael Turner, a cosmologist and professor emeritus at the University of Chicago, who described Dr. Bardeen as a “gentle giant.”
James Maxwell Bardeen was born in Minneapolis on May 9, 1939. His mother, Jane Maxwell Bardeen, was a zoologist and high school teacher. After his father’s business, the family moved to Washington, D.C.; To the Summit, NJ; Then to Champaign-Urbana, Illinois, where you graduate from University of Illinois High School Laboratory.
He attended Harvard University and graduated with a degree in physics in 1960, despite his father’s advice that biology was the wave of the future. “Everyone knows who my father is,” he said in an oral history interview recorded by the Federal University of Paraguay in 2020, adding that he did not feel the need to compete with him. “It was impossible anyway,” he said.
Work under the supervision of a physicist Richard Feynman And an astrophysicist William Fowler (who would both become Nobel Prize laureates), Dr. Bardeen received his Ph.D. He received his Ph.D. from the California Institute of Technology in 1965. His thesis was on the structure of supermassive stars millions of times the mass of the Sun. Astronomers are beginning to suspect that they are the source of the massive energies of quasars detected in the cores of distant galaxies.
After holding postdoctoral positions at the California Institute of Technology and the University of California, Berkeley, he joined the Department of Astronomy at the University of Washington in 1967. An enthusiastic hiker and mountaineer, he was drawn to the school by its easy access to the outdoors.
By then, what a Nobel Prize winner Cape Thorne, a professor at the California Institute of Technology, points out that the golden age of black hole research was in full swing, and Dr. Bardeen was swept up in international meetings. At one, in Paris in 1967, he met Nancy Thomas, a Connecticut high school teacher who was trying to improve her French. They married in 1968.
In addition to his son William, a senior vice president and chief strategy officer of The New York Times Company, and his brother William, Dr. Bardeen’s wife survives him, along with another son, David, and two grandchildren. Sister Elizabeth Gretke passed away in 2000.
Dr. Bardeen was a member of the National Academy of Sciences as well as his brother and father.
Although he was fast at math, Dr. Bardeen didn’t write faster than he spoke. William Price, a former student of Dr. Thorne now at the University of Texas, remembers being sent to Seattle to finish a paper Dr. Bardeen was supposed to write. Nothing is written. Dr. Bardeen’s wife then ordered the two to sit at opposite ends of the sofa with a sheet. Dr. Bardeen would write a sentence and pass the paper on to Dr. Press, who would either reject it or approve it and then put the pillow back. Dr. Bryce said that each sentence took a few minutes. It took them three days, but the paper was written.
One of the historical moments in those years was the month-long “Summer School” in Les Hoechs, France, in 1972 that included all the eminent black hole scientists. Dr. Bardeen was one of six invited speakers. It was during that meeting, Stephen Hawking from the University of Cambridge and Brandon Carternow from the Paris Observatory, wrote a landmark paper called “The Four Laws of Black Hole Mechanics,” which became a springboard for future work, including Dr. Hawking’s surprising calculation that black holes can leak and eventually explode.
In another famous account that same year, Dr. Bardeen deduced the shape and size of a black hole’s “shadow” as seen against a field of distant stars – a circle of light surrounding dark space.
Dr. Thorne said the shape was made famous by the Event Horizon Telescope observations of black holes in the galaxy M87 and at the center of the Milky Way, and by visualizations in the movie “Interstellar.”
Cosmology was among Dr. Bardeen’s other interests. In a 1982 paper, he, Dr. Turner and Paul Steinhardt of Princeton described how submicroscopic fluctuations in matter and energy density in the early universe would grow and give rise to the pattern of galaxies we see in the sky today.
Dr. Turner said, “Jim was glad we used his formalities, and he was sure we got it right.”
Dr. Bardeen transferred to Yale University in 1972. After four years, dissatisfied with the academic bureaucracy in the East and anxious abroad again, he returned to the University of Washington. Retired in 2006.
But it did not stop working. Dr. Thorne recounted a recent telephone conversation in which they recalled the hiking and camping trips they used to take with their families. In the same conversation, Dr. Bardeen described the last thoughts he had about what happens when a black hole evaporates, noting that it might turn into a white hole,
“This was one aspect of Jim in a nutshell, thinking deeply about physics in new creative ways until the end of his life,” Dr. Thorne wrote in an email.
“Reader. Infuriatingly humble coffee enthusiast. Future teen idol. Tv nerd. Explorer. Organizer. Twitter aficionado. Evil music fanatic.”
Astronaut study reveals effects of space travel on human bones – The Jakarta Post – The Jakarta Post
Will Dunham (Reuters)
Washington, United States ●
Mon, July 4, 2022
A study of bone loss in 17 astronauts who flew aboard the International Space Station is providing a fuller understanding of the effects of space travel on the human body and steps that can mitigate it, crucial knowledge ahead of potential ambitious future missions.
The research amassed new data on bone loss in astronauts caused by the microgravity conditions of space and the degree to which bone mineral density can be regained on Earth. It involved 14 male and three female astronauts, average age 47, whose missions ranged from four to seven months in space, with an average of about 5-1/2 months.
A year after returning to Earth, the astronauts on average exhibited 2.1% reduced bone mineral density at the tibia – one of the bones of the lower leg – and 1.3% reduced bone strength. Nine did not recover bone mineral density after the space flight, experiencing permanent loss.
“We know that astronauts lose bone on long-duration spaceflight. What’s novel about this study is that we followed astronauts for one year after their space travel to understand if and how bone recovers,” said University of Calgary professor Leigh Gabel, an exercise scientist who was the lead author of the research published this week in the journal Scientific Reports.
“Astronauts experienced significant bone loss during six-month spaceflights – loss that we would expect to see in older adults over two decades on Earth, and they only recovered about half of that loss after one year back on Earth,” Gabel said.
The bone loss occurs because bones that typically would be weight-bearing on Earth do not carry weight in space. Space agencies are going to need to improve countermeasures – exercise regimes and nutrition – to help prevent bone loss, Gabel said.
“During spaceflight, fine bone structures thin, and eventually some of the bone rods disconnect from one another. Once the astronaut comes back to Earth, the remaining bone connections can thicken and strengthen, but the ones that disconnected in space can’t be rebuilt, so the astronaut’s overall bone structure permanently changes,” Gabel said.
The study’s astronauts flew on the space station in the past seven years. The study did not give their nationalities but they were from the U.S. space agency NASA, Canadian Space Agency, European Space Agency and Japan Aerospace Exploration Agency.
Space travel poses various challenges to the human body – key concerns for space agencies as they plan new explorations. For instance, NASA is aiming to send astronauts back to the moon, a mission now planned for 2025 at the earliest. That could be a prelude to future astronaut missions to Mars or a longer-term presence on the lunar surface.
“Microgravity affects a lot of body systems, muscle and bone being among them,” Gabel said.
“The cardiovascular system also experiences many changes. Without gravity pulling blood towards our feet, astronauts experience a fluid shift that causes more blood to pool in the upper body. This can affect the cardiovascular system and vision.
“Radiation is also a large health concern for astronauts as the further they travel from Earth the greater exposure to the sun’s radiation and increased cancer risk,” Gabel said.
The study showed that longer space missions resulted both in more bone loss and a lower likelihood of recovering bone afterward. In-flight exercise – resistance training on the space station – proved important for preventing muscle and bone loss. Astronauts who performed more deadlifts compared to what they usually did on Earth were found to be more likely to recover bone after the mission.
“There is a lot we still do not know regarding how microgravity affects human health, particularly on space missions longer than six months, and on the long-term health consequences,” Gabel said. “We really hope that bone loss eventually plateaus on longer missions, that people will stop losing bone, but we don’t know.”
Rocket Lab Moon Mission for NASA a Success – Business Wire
LONG BEACH, Calif.–(BUSINESS WIRE)–Rocket Lab USA, Inc. (Nasdaq: RKLB) (“Rocket Lab” or “the Company”), a leading launch and space systems company, today announced it has successfully deployed a pathfinding satellite for NASA, setting it on a course to the Moon. The deployment marks the successful completion of Rocket Lab’s first deep space mission, paving the way for the Company’s upcoming interplanetary missions to Mars and Venus.
Owned and operated by Advanced Space on behalf of NASA, the Cislunar Autonomous Positioning System Technology Operations and Navigation Experiment (CAPSTONE) will be the first spacecraft to test the Near Rectilinear Halo Orbit (NRHO) around the Moon. This is the same orbit intended for NASA’s Gateway, a Moon-orbiting outpost that will provide essential support for long-term astronaut lunar missions as part of the Artemis program.
Rocket Lab’s role in the mission took place over two phases. First, CAPSTONE was successfully launched to low Earth orbit by Rocket Lab’s Electron launch vehicle on June 28th. From there, Rocket Lab’s Lunar Photon spacecraft provided in-space transportation, power, and communications to CAPSTONE. After six days of orbit-raising burns by Lunar Photon’s 3D printed HyperCurie engine, CAPSTONE was deployed on its ballistic lunar transfer trajectory to the Moon as planned at 07:18 UTC on July 4th. The mission was Rocket Lab’s fourth Electron launch this year, demonstrating the rocket’s continued reliability. In addition to providing the launch, Rocket Lab designed, manufactured, and operated the Lunar Photon spacecraft, successfully completing a highly complex deep space mission and demonstrating Rocket Lab’s growing capabilities as an end-to-end space company.
“The CAPSTONE mission marks the beginning of humanity’s return to the Moon through NASA’s Artemis program and we’re incredibly proud that Rocket Lab has played a key role in that,” said Rocket Lab founder and CEO, Peter Beck. “The Rocket Lab team has been working on CAPSTONE with NASA and our mission partners for more than two years, developing new small satellite technology in the form of the Lunar Photon spacecraft to make this mission possible, so it’s an incredible feeling after all that hard work and innovation to achieve mission success and set CAPSTONE on a course for the Moon. This has been Rocket Lab’s most complex mission to date and our team has been incredible. We pushed Electron and Photon to their limits and proved it’s possible to do big missions with small spacecraft. Now we’ll be applying this ground-breaking technology for more interplanetary journeys, including our upcoming missions to Venus and Mars.”
With Rocket Lab’s role in the mission now complete, CAPSTONE’s solo journey to the Moon has begun. CAPSTONE will use its own propulsion and the Sun’s gravity to navigate the rest of the way to the Moon, a four-month journey that will have CAPSTONE arriving to its lunar orbit on November 13, 2022. The gravity-driven track will dramatically reduce the amount of fuel the CubeSat needs to get to the Moon. Advanced Space and Terran Orbital will manage the operation of the CAPSTONE satellite for the duration of its orbital lifespan.
The CAPSTONE mission was Rocket Lab’s 27th Electron launch overall, but it featured several significant technological firsts for the Company, including:
- First deep space mission.
- First use of Lunar Photon, a high energy variant of the Rocket Lab-designed and built Photon spacecraft. Rocket Lab previously launched and continues to operate two low Earth orbit variants of the Photon spacecraft.
- First collaborative mission between Rocket Lab and Advanced Solutions Inc, a Colorado-based flight-software company acquired by Rocket Lab in late 2021.
- First time using the FR-lite satellite radio which Rocket Lab has an exclusive license agreement with Johns Hopkins University Applied Physics Laboratory to manufacture.
- First mission where Electron’s second stage deorbited the same day as launch.
- First mission planning and executing lunar trajectories.
- At 300 kg (661 lbs) of payload mass, the mission was Electron’s heaviest lift to date.
CAPSTONE was the first in a series of interplanetary missions for Rocket Lab’s Photon spacecraft, including the ESCAPADE mission to Mars in 2024 and Rocket Lab’s upcoming private mission to Venus.
Advanced Space of Colorado, a leading commercial space solutions company, owns the CAPSTONE satellite and operates the mission. CAPSTONE was designed and built by Terran Orbital. CAPSTONE development is supported by NASA’s Space Technology Mission Directorate via the Small Spacecraft Technology Program at NASA’s Ames Research Center in California’s Silicon Valley. Advanced Exploration Systems within NASA’s Human Exploration and Operations Mission Directorate supports the launch and mission operations. NASA’s Launch Services Program at Kennedy Space Center in Florida is responsible for launch management.
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+ About Rocket Lab
Founded in 2006, Rocket Lab is an end-to-end space company with an established track record of mission success. We deliver reliable launch services, satellite manufacture, spacecraft components, and on-orbit management solutions that make it faster, easier and more affordable to access space. Headquartered in Long Beach, California, Rocket Lab designs and manufactures the Electron small orbital launch vehicle and the Photon satellite platform and is developing the Neutron 8-ton payload class launch vehicle. Since its first orbital launch in January 2018, Rocket Lab’s Electron launch vehicle has become the second most frequently launched U.S. rocket annually and has delivered 147 satellites to orbit for private and public sector organizations, enabling operations in national security, scientific research, space debris mitigation, Earth observation, climate monitoring, and communications. Rocket Lab’s Photon spacecraft platform has been selected to support NASA missions to the Moon and Mars, as well as the first private commercial mission to Venus. Rocket Lab has three launch pads at two launch sites, including two launch pads at a private orbital launch site located in New Zealand and a second launch site in Virginia, USA which is expected to become operational in 2022. To learn more, visit www.rocketlabusa.com.
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