#telescope_technology

[phonemantra-blog]

New observations from the JWST space telescope have revealed several details about the surface of Ganymede, Jupiter's largest moon. Ganymede is almost a planet, except that it does not revolve around the Sun, but around Jupiter. If it revolved around the Sun instead of Jupiter, it would have the status of a planet. It has a complex structure - a molten core that creates a magnetic field, a surface layer similar to that on Earth, and an ice sheet with a hidden underwater ocean. The satellite even has an atmosphere, although its density is low. Ganymede is even larger than Mercury and approaches Mars in size. The Galileo and Juno missions, as well as telescopes on Earth, studied the chemical composition of Ganymede's surface. However, with such extensive knowledge, unknown details remain, especially regarding its surface. In a new study, a team of researchers from the United States, Europe, and Japan examined the surface of Ganymede using the JWST space telescope's NIRSpec and MIRI instruments. The main author of the study was French planetary scientist D. Bochelet-Morvan from LESIA, an observatory in Paris. [caption id="attachment_76971" align="aligncenter" width="600"] JWST space telescope[/caption] The surface of Ganymede consists of two types of relief: light icy areas with troughs and dark areas. Light areas occupy about two-thirds of the surface, and dark areas occupy the rest. Both types of landforms are ancient, but the darker areas are older and have many craters. In this case, the light relief penetrates through the dark one. The JWST space telescope studied in detail Ganymede CO2 is present on Ganymede, but it is associated with other molecules, which especially attracts the attention of scientists. Mapping the distribution of carbon dioxide will help figure out how it is bound to which molecules. There is also water ice on Ganymede, but it is amorphous. JWST carried out a mapping of ice distribution and properties. Based on the temperature range, no clear surface ice was found on Ganymede. JWST observations indicate that some CO2 is bound to water ice, but only about 1% by mass. The rest of the CO2 is found in various minerals and salts. The greatest amount of water ice is observed in the areas of Ganymede's poles, where ions from Jupiter bombard the surface of the satellite. It may also be due to a combination of micrometeorites that become embedded in the ice and ions that reactivate water vapor in non-ice-covered areas and form cleaner water ice, which JWST easily detects. In addition, scientists note differences between the poles of Ganymede and other regions of its surface. Part of these differences are due to Jupiter's strong influence on its moon. The connection between Jupiter and Ganymede can be compared to the connection between the Sun and the Earth. Just as the solar wind affects the Earth's magnetosphere, the plasma emanating from Jupiter affects Ganymede. In addition, Ganymede's magnetic field interacts with Jupiter's magnetic field, which contributes to the formation of auroras on Jupiter. The connections between Jupiter and Ganymede are complex, with some effects extending to Ganymede's surface chemistry due to the irradiation of the moon's poles by Jupiter's plasma. New research has greatly expanded our understanding of these aspects, but scientists have not yet been able to fully interpret the observations. As the authors of the study note, the results obtained will significantly help in optimizing future observations using the MAJIS spectrometer of the JUICE (JUpiter ICy Moons Explorer) mission, which will continue research on Ganymede. The mission was launched in the spring and will reach Jupiter in the summer of 2031. 

[phonemantra-blog]

The telescope will make breakthroughs in astronomy and raise China's scientific research to the international level The Xuntian telescope has become the most important scientific project since the launch of our country's space station. China is preparing a major project that will not only expand the nation's astronomy research program but also increase the use of the country's space station. The space telescope is called Xuntian, also known as the Chinese Survey Space Telescope, or Chinese Space Station Telescope (CSST). The name “Xuntian” can be translated as “study of the firmament”, or “exploration of the heavens”. [caption id="attachment_64042" align="aligncenter" width="780"] Xuntian space telescope[/caption] new Xuntian space telescope will surpass Hubble in astronomical research. Scheduled for launch next year, the 2-meter CSST space telescope, about the size of a school bus, will share an orbit with China's Tiangong space station, where Chinese astronauts can periodically retool the telescope itself. Its service life is expected to be 10 years, but the telescope's operating time can be extended. Xuntian is designed with the ambition to surpass the Hubble Space Telescope. Lin Siqian, deputy director of the China Space Exploration Agency, said that the telescope is expected to make breakthroughs in cosmology, the study of dark matter and dark energy in our and nearby galaxies, star formation processes, and the study of exoplanets. These are very ambitious goals. Lin said the telescope's 2.5 billion-pixel camera will take high-resolution images to depths of up to 17,500 square degrees. The resolution will be about the same as Hubble, but its field of view will be more than 300 times wider. A telescope's field of view is the area that the telescope can see at one time. In an interview last year, Li Ran, a project scientist for CSST's scientific data systems, used the analogy of taking pictures of a herd of sheep to explain CSST's capabilities: "Hubble can see one sheep, but CSST can see thousands, all with the same resolution." The launch of Xuntian into Earth orbit is expected in 2024 using a Long March 5B rocket.

[phonemantra-blog]

Hydrogen Epoch of Reionization Array (HERA) is a new radio telescope in South Africa that will be able to observe giant clouds of hydrogen and track possible traces of dark matter decay Hydrogen is the most abundant element in the Universe. It makes up more than 90% of all atoms, exceeding helium atoms ten times and all other elements combined by a hundred times. Hydrogen is present everywhere - from the water in the oceans to the most distant regions of the Cosmic Dawn. Astronomers are interested in neutral hydrogen, which can emit weak radio emissions. Line 21 cm is the result of the transition of a hydrogen electron from one energy state to another. This occurs when the spins of the electron and proton bound by a hydrogen molecule are oriented in the same way. If the spins are aligned, the energy of hydrogen will be slightly higher. However, when the spins are in opposite directions, the electron can change its spin by emitting a photon. The emission of a photon can occur spontaneously. Therefore, wherever hydrogen clouds are concentrated, they emit radio energy with a wavelength of 21 cm. This property of neutral hydrogen helps astronomers study its movement in the Universe and its cosmological redshift. In one of the first experiments using this method to study the movement of hydrogen in the Milky Way and nearby galaxies, astronomer Vera Rubin was able to detect the presence of dark matter. Now a new study shows that the 21 cm line may provide the first evidence for the existence of dark matter particles. [caption id="attachment_53555" align="aligncenter" width="780"] telescope[/caption] New telescope could detect decaying dark matter in the early universe The study will take place on the Hydrogen Epoch of Reionization Array (HERA) radio telescope, located in South Africa and optimized for observing hydrogen in the early stages of the Universe. Once launched, HERA will map the large-scale structure of hydrogen during the time of cosmic darkness and the emergence of the first stars and galaxies. At this time, the Universe was filled with dark matter and clouds of hydrogen. If dark matter is truly neutral and only interacts gravitationally with matter and light, the 21 cm line becomes the only light emitted in the early stages of the Universe. However, the most common model of dark matter involves the existence of particles known as weakly interacting massive particles (WIMPs). Neutral dark matter particles are significantly heavier than ordinary matter particles such as protons and electrons. In certain cases, dark matter particles can decay into ordinary matter, creating positrons, electrons, protons, and antiprotons. In this case, energetic decay particles will also interact in the radio range with a wavelength of 21 cm. Based on observations of the cosmic background and other studies, it is known that the half-life of WIMP particles is very long. So far, we have not found any evidence of dark matter decay, which could mean that these particles either do not exist or have a half-life of more than a trillion years. New research shows that even with a thousandfold increase in half-life, HERA will be able to detect its presence in the early Universe. This will require only 1000 hours of observation. Even if HERA does not find any evidence of dark matter decay, the data obtained from HERA may rule out some WIMP models and narrow the choice of models from the group.