This launch had a rocketcam that sent views from the Soyuz all the way to orbit. Here is a screen capture of the upper stage falling away from the capsule:
A two meter wide meteoroid was tracked in space last Saturday and later that day he created a fireball over South Africa. This video shows the “Meteor 2018 LA (ZLAF9B2) [as] seen from farm between Ottosdal and Hartebeesfontein North West South Africa”:
A boulder-sized asteroid designated 2018 LA was discovered Saturday morning, June 2, and was determined to be on a collision course with Earth, with impact just hours away. Because it was very faint, the asteroid was estimated to be only about 6 feet (2 meters) across, which is small enough that it was expected to safely disintegrate in Earth’s atmosphere. Saturday’s asteroid was first discovered by the NASA-funded Catalina Sky Survey, located near Tucson and operated by the University of Arizona.
Although there was not enough tracking data to make precise predictions ahead of time, a swath of possible locations was calculated stretching from Southern Africa, across the Indian Ocean, and onto New Guinea. Reports of a bright fireball above Botswana, Africa, early Saturday evening match up with the predicted trajectory for the asteroid. The asteroid entered Earth’s atmosphere at the high speed of 10 miles per second (38,000 mph, or 17 kilometers per second) at about 16:44 UTC (9:44 a.m. PDT, 12:44 p.m. EDT,6:44 p.m. local Botswana time) and disintegrated several miles above the surface, creating a bright fireball that lit up the evening sky. The event was witnessed by a number of observers and was caught on webcam video [see above].
When it was first detected, the asteroid was nearly as far away as the Moon’s orbit, although that was not initially known. The asteroid appeared as a streak in the series of time-exposure images taken by the Catalina telescope. As is the case for all asteroid-hunting projects, the data were quickly sent to the Minor Planet Center in Cambridge, Massachusetts, which calculated a preliminary trajectory indicating the possibility of an Earth impact. The data were in turn sent to the Center for Near-Earth Object Studies (CNEOS) at NASA’s Jet Propulsion Laboratory in Pasadena, California, where the automated Scout system also found a high probability that the asteroid was on an impact trajectory. Automated alerts were sent out to the community of asteroid observers to obtain further observations, and to the Planetary Defense Coordination Office at NASA Headquarters in Washington. However, since the asteroid was determined to be so small and therefore harmless, no further impact alerts were issued by NASA.
“This was a much smaller object than we are tasked to detect and warn about,” said Lindley Johnson, Planetary Defense Officer at NASA Headquarters. “However, this real-world event allows us to exercise our capabilities and gives some confidence our impact prediction models are adequate to respond to the potential impact of a larger object.”
The ATLAS asteroid survey obtained two additional observations hours before impact, which were used by Scout to confirm the impact would occur, and narrowed down the predicted location to southern Africa. Infrasound data collected just after the impact clearly detected the event from one of the listening stations deployed as part of the International Monitoring System of the Comprehensive Nuclear-Test-Ban Treaty. The signal is consistent with an atmospheric impact over Botswana.
“The discovery of asteroid 2018 LA is only the third time that an asteroid has been discovered to be on an impact trajectory, said Paul Chodas, manager of the Center for Near-Earth Object Studies (CNEOS) at JPL. “It is also only the second time that the high probability of an impact was predicted well ahead of the event itself.”
The first event of this kind was the impact of asteroid 2008 TC3, which lit up the predawn sky above Northern Sudan on October 7, 2008. That was a slightly larger asteroid (about 13 feet, or 4 meters in size), and it was discovered a full 19 hours before impact, allowing for a large number of follow-up observations and a very precise trajectory to be calculated. The second predicted impact event was for asteroid 2014 AA, which was discovered only a few hours before impact on Jan. 1, 2014, in the Atlantic Ocean, leaving too little time for follow-up observations. The Catalina Sky Survey has been responsible for discovering all three of these small asteroids on impact trajectories, and all on the watch of the same observer, Richard Kowalski.
NASA’s Planetary Defense Coordination Office is responsible for finding, tracking and characterizing potentially hazardous asteroids and comets coming near Earth, issuing warnings about possible impacts, and assisting coordination of U.S. government response planning, should there be an actual impact threat. JPL hosts the Center for Near-Earth Object Studies for NASA’s Near-Earth Object Observations Program, an element of the Planetary Defense Coordination Office within the agency’s Science Mission Directorate.
1. Monday, June 4, 2018; 2-3:30 pm PDT (4-5:30 pm CDT, 5-6:30 pm EDT): No show today due to host taking a personal holiday.
2. Tuesday, June 5, 2018: 7-8:30 pm PDT; 9-10:30 pm CDT; 10-11:30 pm EDT: We welcome back welcome back Dr. Rob Kelso re returning to the Moon and more.
3. Wednesday, June 6, 2018: Hotel Mars. See Upcoming Show Menu and the website newsletter for details. Hotel Mars is pre-recorded by John Batchelor. It is archived on The Space Show site after John posts it on his website.
4. Friday, June 8, , 2018; 9:30 am -11 am PDT, (12:30 -2 pm EDT; 11:30 am -1 pm CDT): We welcome Dr. John Connolly CONNOLLY, head of NASA Humans To Mars Program.
5. Sunday, June 10, 2018: 12-1:30 pm PDT; 2-3:30 pm CDT; 3-4:30 pm EDT. OPEN LINES. All space and science calls welcome. The topics you want to talk about. First time callers welcome
This artist’s impression shows a dusty galaxy in the distant Universe that is forming stars at a rate much higher than in our Milky Way. New ALMA observations have allowed scientists to lift the veil of dust and see what was previously inaccessible — that such starburst galaxies have an excess of massive stars as compared to more peaceful galaxies. [ Larger images ]Astronomers using ALMA and the VLT have discovered that both starburst galaxies in the early Universe and a star-forming region in a nearby galaxy contain a much higher proportion of massive stars than is found in more peaceful galaxies. These findings challenge current ideas about how galaxies evolved, changing our understanding of cosmic star-formation history and the build up of chemical elements.
Probing the distant Universe a team of scientists, led by University of Edinburgh astronomer Zhi-Yu Zhang, used the Atacama Large Millimeter/submillimeter Array (ALMA) to investigate the proportion of massive stars in four distant gas-rich starburst galaxies[1]. These galaxies are seen when the Universe was much younger than it is now so the infant galaxies are unlikely to have undergone many previous episodes of star formation, which might otherwise have confused the results.
This gigantic star-forming region in the Milky Way’s neighbour galaxy the Large Magellanic Cloud is the birthplace of an astonishing number of massive stars, some of which might have masses of up to 300 solar masses. [Larger images]Zhang and his team developed a new technique — analogous to radiocarbon dating (also known as carbon-14 dating) — to measure the abundances of different types of carbon monoxide in four very distant, dust-shrouded starburst galaxies [2]. They observed the ratio of two types of carbon monoxide containing different isotopes [3].
“Carbon and oxygen isotopes have different origins”, explains Zhang. “18O is produced more in massive stars, and 13C is produced more in low- to intermediate-mass stars.”
Thanks to the new technique the team was able to peer through the dust in these galaxies and assess for the first time the masses of their stars.
The mass of a star is the most important factor determining how it will evolve. Massive stars shine brilliantly and have short lives and less massive ones, such as the Sun, shine more modestly for billions of years. Knowing the proportions of stars of different masses that are formed in galaxies therefore underpins astronomers’ understanding of the formation and evolution of galaxies throughout the history of the Universe. Consequently, it gives us crucial insights about the chemical elements available to form new stars and planets and, ultimately, the number of seed black holes that may coalesce to form the supermassive black holes that we see in the centres of many galaxies.
Co-author Donatella Romano from the INAF-Astrophysics and Space Science Observatory in Bologna explains what the team found:
“The ratio of 18O to 13C was about 10 times higher in these starburst galaxies in the early Universe than it is in galaxies such as the Milky Way, meaning that there is a much higher proportion of massive stars within these starburst galaxies.”
The ALMA finding is corroborated by another discovery in the local Universe. A team led by Fabian Schneider of the University of Oxford, UK, made spectroscopic measurements with ESO’s Very Large Telescope of 800 stars in the gigantic star-forming region 30 Doradus in the Large Magellanic Cloud in order to investigate the overall distribution of stellar ages and initial masses [4].
This image shows the four distant starburst galaxies observed by ALMA. The top images depict the 13CO emission from each galaxy, while the bottom ones show their C18O emission. The ratio of these two isotopologues allowed astronomers to determine that these starburst galaxies have an excess of massive stars. [ Larger images ]Schneider explained,
“We found around 30% more stars with masses more than 30 times that of the Sun than expected, and about 70% more than expected above 60 solar masses. Our results challenge the previously predicted 150 solar mass limit for the maximum birth mass of stars and even suggest that stars could have birth masses up to 300 solar masses!”
Rob Ivison, co-author of the new ALMA paper, concludes:
“Our findings lead us to question our understanding of cosmic history. Astronomers building models of the Universe must now go back to the drawing board, with yet more sophistication required.”
Notes [1] Starburst galaxies are galaxies that are undergoing an episode of very intense star formation. The rate at which they form new stars can be 100 times or more the rate in our own galaxy, the Milky Way. Massive stars in these galaxies produce ionising radiation, stellar outflows, and supernova explosions, which significantly influence the dynamical and chemical evolution of the medium around them. Studying the mass distribution of stars in these galaxies can tell us more about their own evolution, and also the evolution of the Universe more generally.
[2] The radiocarbon dating method is used for determining the age of an object containing organic material. By measuring the amount of 14C, which is a radioactive isotope whose abundance continuously decreases, one can calculate when the animal or plant died. The isotopes used in the ALMA study, 13C and 18O, are stable and their abundances continuously increase during the lifetime of a galaxy, being synthesised by thermal nuclear fusion reactions inside stars.
[3] These different forms of the molecule are called isotopologues and they differ in the number of neutrons they can have. The carbon monoxide molecules used in this study are an example of such molecular species, because a stable carbon isotope can have either 12 or 13 nucleons in its nucleus, and a stable oxygen isotope can have either 16, 17, or 18 nucleons.
[4] Schneider et al. made spectroscopic observations of individual stars in 30 Doradus, a star-forming region in the nearby Large Magellanic Cloud, using the Fibre Large Array Multi Element Spectrograph (FLAMES) on the Very Large Telescope (VLT). This study was one of the first to be carried out that has been detailed enough to show that the Universe is able to produce star-forming regions with different mass distributions from that in the Milky Way.
