Space News & Blog Articles

It looks like South Korea just joined the most exclusive club on the planet! With the launch of its Korea Satellite Launch Vehicle II (KSLV-II aka. the “Nuri” rocket) on June 21st, the country became the latest nation to demonstrate its ability to build and launch its own rockets to space. This was the Nuri’s second launch attempt, which took place eight months after the first attempt failed to deliver a test satellite to orbit back. This time, the rocket managed to reach space and deliver a payload of satellites, making South Korea the eleventh nation to launch from its soil and the seventh to launch commercial satellites.

The Nuri rocket (Korean for “world”) is a three-stage liquid-fuel heavy launch vehicle that stands 47.2 meters (155 feet) tall and weighs roughly 200 metric tons (220 U.S. tons). This vehicle is the second rocket developed by South Korea and is the successor to the Naro-1 (KSLV-1). The first launch attempt took place on October 21st, 2021, which saw the Nuri rocket successfully reach an altitude of 700 km (430 mi) and the successful deployment of its 1,500 kg (3,300 lbs) payload (the test satellite). However, a technical issue with the 3rd stage prevented it from reaching deployment altitude and placing the satellite in orbit.

The second attempt (Tuesday, June 21st) saw the rocket launch from the Naro Space Center in Goheung, South Korea, at 07:00 GMT (03:00 PM EDT; 12:00 PM PDT). This time, the rocket reached space and successfully deployed its entire 1,500 kg (3,300) payload to orbit. This included a smaller test satellite (1300 kg; 2,900 lbs) and a 180 kg (400 lbs) payload consisting of a rocket launch verification satellite and four research CubeSats developed by local universities.

The previous nation to enter the space launch club was North Korea, which successfully launched an Earth observation satellite (Kwangmyongsong-3 Unit 2) atop an Unha-3 rocket in December of 2012. However, both the rocket and the payload were considerably less sophisticated than that of their South Korean counterparts. The three-stage Unha rocket, which is largely derived from the North Korean Taepodong-2 nuclear delivery system, weighs about 86,750 kg (191,250 lbs) and can deliver only 200 kg (lbs) to orbit.

The Nuri rocket, meanwhile, is capable of delivering 1,500 kg to 2,600 kg (3,300 to 5,700 lbs) to LEO (depending on the altitude), which works out to a mass-to-payload ratio (aka. payload fraction) of 77 to 1. While this lags significantly behind other heavy launch systems used today, it is significantly better than Unhi’s paltry payload fraction of 433.75 to 1! And whereas North Korea has launched only one Earth observation satellite (Kwangmyongsong-4) since 2012, this latest test launch represents a major step for South Korea, which is likely to commit to regular launch schedules soon.

SN 1054 was one of the most spectacular astronomical events of all time. The supernova explosion eventually formed what is today known as the M1 – the Crab Nebula. But in 1054 AD, the year it occurred, it was an ultrabright star in the sky and one of only eight recorded supernovae in the history of the Milky Way. However, it was only noted by half of the literate world. Primarily written about in the East, especially in China, SN 1054 was almost wholly absent from the Western record. Except, potentially, for a subtle hint at it in the most unlikely of places – some Byzantine coins.

At least, that is the new theory according to a multinational group of researchers in the European Journal of Science and Theology. They found that a special version of a coin minted by Byzantine Emperor Constantine IX showed two stars around the emperor’s head – potentially representing a nod to the existence of SN 1054, despite any written evidence for the supernova’s existence elsewhere in the Christian world.

Scholars in Japan, China, and the Islamic world had no problem noticing the new bright star in the sky. So why didn’t the Christians? There has been an ongoing debate in the history of astronomy community surrounding this question for decades, with no definitive answer. However, the general consensus is that Christian scholars feared that pointing out a change in what, at the time, were thought to be the perfect and inviolable heavens would cause too much of a ruckus within the church. Theological doctrine held sway in the Christian world at the time, and calling into question any part of that doctrine could lead to ex-communication or even death. It would have to be a brave scholar to risk such a fate for no tangible reward.

Which makes it even more interesting that a metalworker, or maybe one of the otherwise cowed scholars, might have had the nerve to do so. The researchers found a special edition of a coin, known in the technical jargon as the Constantine IX Monomachos Class IV coin, which has two stars compared to the single star noticeable on the other three classes of coins minted during the monarch’s reign. 

The Class IV is thought to be minted between the summer of 1054 and the spring of 1055 and has two noticeable stars on either side of the monarch’s head. One star is thought to represent Venus, the Morning Star, while the monarch’s head itself is believed to represent the sun. The other star, though, could potentially represent the “guest star” (as Chinese observers called it) of the SN 1054 supernova.

Located in the Northern Cape of South Africa, the MeerKAT telescope consists of 64 powerful radio antennas dedicated to probing the mysteries of the Universe. This facility is a precursor to the future Square Kilometer Array Observatory (SKAO), which will consist of MeerKAT and the Hydrogen Epoch of Reionization Array (HERA) in South Africa and the Australian SKA Pathfinder (ASKAP) and Murchison Radio-astronomy Observatory in Australia. A primary aim of the SKAO is to understand the matter content of the Universe and what mechanisms are driving its evolution and expansion.

The best way to do this is to observe the structure of the Universe on the largest of scales, where astronomers can observe the distribution of galaxies, the nature of gravity, and the role of dark matter and dark energy. To this end, an international team of astronomers has combined the power of MeetKAT’s 64 radio telescopes to detect faint signatures of neutral hydrogen gas across cosmological scales. The resulting accuracy and sensitivity provide a demonstration of what the SKAO will be able to achieve in the near future.

The international team’s findings are described in a recent paper that appeared online and was submitted for publication by the Monthly Notices of the Royal Astronomical Society. The team was led by Steven Cunnington of the Jodrell Bank Centre for Astrophysics and included members from the South African Radio Astronomy Observatory (SARAO), the Shanghai Astronomical Observatory, the Istituto Nazionale di Fisica Nucleare (INFN), the Instituto de Astrofísica e Ciências do Espaçol, the NAOC-UKZN Computational Astrophysics Center, and multiple research institutes and Universities.

A ‘radio color’ view of the sky above the Murchison Widefield Array radio telescope. Credit: Natasha Hurley-Walker (ICRAR/Curtin), GLEAM Team; ICRAR/Dr. John Goldsmith/Celestial Visions

Radio telescopes are immensely valuable when it comes to cosmology, which is the study of the origin, evolution, and future of the Universe. In particular, radio telescopes can detect radiation at wavelengths of 21 cm, a part of the radio spectrum generated by neutral hydrogen. As the most abundant element in the Universe today, analyzing it in three dimensions allows astronomers to map the total distribution of matter in the Universe. It also permeated the cosmos a few hundred thousand years after the Big Bang, when the first stars and galaxies were only beginning to form.

The Universe’s giant galaxies pose a thorny problem for astronomers. The galaxies have grown large somehow, and the only things that can make a galaxy giant are probably other galaxies. So mergers must have played an important role.

Astronomers have known about galaxy mergers for a long time, but the process is still mysterious. A new study based on ten years of work presents observations and direct measurements of the galaxy merger process that remove some of the mystery.

It seems axiomatic that galaxies grow large by merging with other galaxies. Where else could they acquire so much mass? Galaxies are the largest, most massive, distinct structures in the Universe. Galaxy clusters and groups are larger, but they’re collective structures made of distinct, individual galaxies that are associated but not interacting. For a giant galaxy like our Milky Way—or our even larger neighbour, the Andromeda Galaxy—to grow so massive, it had to acquire large amounts of mass. And the only available sources of large-scale mass are other galaxies.

Galaxy formation is an active area of study in cosmology, and the theoretical work on galaxy mergers is substantial. But observations and detailed conclusions have lagged behind.

The Hubble and other telescopes have captured many images that look like galaxies in the process of merging. But there’s more than meets the eye here, at least there was in the Hubble Space Telescope’s earlier days. The venerable space telescope lacked the technology to observe the most distant and ancient galaxies with clarity.