China Space Day丨See these Chinese "stars" shining in space

52 years ago, China's first artificial satellite, Dongfanghong-1, was successfully launched, marking the beginning of the Chinese people's exploration of the mysteries of the universe, the peaceful use of space, and the benefit of mankind. To commemorate this feat, my country has set "China Space Day" on April 24 every year. China Space Day has been closely associated with satellites since its birth.

Seven years ago, the first satellite in the Chinese Academy of Sciences' first space science satellite series, the dark matter particle detection satellite "Wukong", was launched into space, marking the entry of my country's space science into a comprehensive exploration stage. Subsequently, many scientific satellites such as "Hui Yan", "Xihe" and "Zhang Heng 1" were launched into space one after another.

On the seventh "China Space Day", let us not forget our original aspirations and take a look at the scientific "stars" shining in the sky now.

Space Earth Science Satellite

Observe people and nature from a different perspective

They are "scouts" of human activities, using their "eagle eyes" to observe how humans and nature interact; they are also "whistlers" for future sustainable development, monitoring uncivilized human behavior. They are space earth science satellites, and seeing the earth from a different angle is their specialty.

"Zhang Heng No. 1"

On February 2, 2018, the electromagnetic monitoring test satellite "Zhang Heng No. 1" was launched into space. Space electromagnetic disturbances have a clear correlation with earthquakes, so building a space electromagnetic monitoring system is of great significance for exploring new methods of earthquake prediction. "Zhang Heng No. 1" is equipped with high-precision magnetometers and induction magnetometer payloads. By acquiring global electromagnetic fields, ionospheric plasma, and high-energy particle observation data, it conducts real-time monitoring of ionospheric dynamics and tracking of earthquake precursors in China and surrounding areas. "Zhang Heng No. 1" is the first in China to achieve high-precision in-situ detection of ionospheric electrons and ions, and the first to achieve north-south conjugate observations of Pc1 geomagnetic pulsations (referring to low-frequency fluctuations with a frequency of 0.2-5 Hz) in the ionosphere, and has obtained China's first batch of global geomagnetic field observation data with completely independent intellectual property rights.

Xinhua News Agency (Photo by Wang Jiangbo)

Carbon Satellite

On December 22, 2016, the Global Carbon Dioxide Monitoring Scientific Experimental Satellite (Carbon Satellite) was launched into space. It carries high-spectral and high-spatial resolution carbon dioxide detectors, multi-spectral cloud and aerosol detectors and other detection equipment, which can truly and objectively reflect the real-time changes in the global atmospheric carbon dioxide content, providing a basis for the quantitative calculation and monitoring of carbon sources and sinks. Relying on Carbon Satellite, Chinese scientists obtained the first global carbon dioxide distribution map and the first global carbon flux data set of China Carbon Satellite; the Institute of Atmospheric Physics of the Chinese Academy of Sciences obtained the sunlight-induced chlorophyll fluorescence data products of terrestrial ecosystems.

(Photo source: Xinhuanet)

"Sustainable Development Science Satellite 1"

On November 5, 2021, the Sustainable Development Science Satellite 1 (SDGSAT-1) was launched into space. It is the world's first scientific satellite dedicated to serving the United Nations 2030 Agenda for Sustainable Development, and its data products are shared globally. It carries three payloads: thermal infrared, low-light and multi-spectral imagers, which will achieve a detailed depiction of "traces of human activities": thermal infrared imagers can accurately detect land surface and water surface temperatures, fine hydrothermal dynamic changes in farmland, urban thermal energy distribution, etc.; low-light imagers have the ability to reflect the level of social and economic development and human settlement patterns by detecting the intensity and distribution of night lights; multi-spectral imagers can monitor and analyze water quality, offshore ecological environment, coastal aquaculture and aquatic plant distribution, as well as glaciers, snow, vegetation coverage, etc. At the end of 2021, the first batch of 11 images of the satellite were officially released, including low-light, multi-spectral and thermal infrared imagers of many regions and cities such as the Yangtze River Delta, Shandong Peninsula, Namtso Lake in Tibet, Aksu in Xinjiang, Beijing, Shanghai and Paris, France.

Multi-spectral remote sensing satellite image of Namtso Lake in Tibet.

(Xinhua News Agency)

Space astronomy satellite

Expanding our understanding of the universe

Looking for evidence of the existence of dark matter, observing black hole explosions, studying the sun's "one magnetic field and two storms"... In recent years, my country has successively developed and launched several space astronomical satellites, continuously expanding the new boundaries of understanding the universe and embarking on a new journey of space science exploration.

Wukong

On December 17, 2015, the "Wukong" dark matter particle detection satellite was successfully launched. This satellite is the space detector of high-energy gamma rays and electron cosmic rays with the widest observation energy range and the best energy resolution so far. "Wukong" shoulders the mission of finding evidence of the existence of dark matter. It can capture 60 high-energy particles per second on average and can measure cosmic ray particles such as electrons and gamma rays with magnitudes ranging from 1 billion electron volts to tens of trillion electron volts. At present, "Wukong" has successively achieved major scientific achievements such as accurately measuring the electron energy spectrum, drawing the high-energy proton cosmic ray energy spectrum, drawing the most accurate high-energy helium nucleus cosmic ray energy spectrum to date, and observing new energy spectrum structures. The first batch of gamma photon scientific data detected by it has also been made public to the world.

(Photo source: Xinhuanet)

Insight satellite

On June 15, 2017, the Insight-HXMT satellite was launched into space. It carries four payloads, including high-energy, medium-energy, and low-energy X-ray telescopes and a space environment monitor. After its launch, the Insight-HXMT satellite has made a series of major scientific achievements, including the observation of gravitational waves from the merger of two neutron stars, a panoramic view of the explosion process of a black hole binary, the high-energy radiation process of the largest flare in the 24th solar cycle, and the direct measurement of the strongest magnetic field in the universe, the high-precision in-orbit verification of pulsar navigation, the discovery of the relativistic jet closest to the black hole, the discovery of high-speed plasma escaping from the black hole, and the discovery and confirmation of the first X-ray burst that occurred simultaneously with a fast radio burst and came from a magnetar (a neutron star with an extremely strong magnetic field).

On February 19, 2021, at a press conference held at the Institute of High Energy Physics (IHEP) of the Chinese Academy of Sciences, Zhang Shuangnan, chief scientist of the Insight-HXMT satellite, introduced the results. Photo by Xinhua News Agency reporter Jin Liwang

Xihe

On October 14, 2021, my country's first solar exploration scientific and technological experimental satellite "Xihe" was successfully launched, marking my country's official entry into the era of space exploration of the sun. "Xihe" adopted the new overall design method of "dynamic and static isolation and non-contact" for the first time, and proposed the "active control of the payload cabin and passive control of the platform cabin" method for the first time. It will realize the full-disk Hα band spectral imaging observation for the first time, and can obtain the change records of physical quantities such as atmospheric temperature and speed during solar eruptions, which will help study the dynamic process and physical mechanism of solar eruptions.

(Photo source: Xinhua News Agency)

Basic Space Physics Satellite

Moving the laboratory into the vast space

Building a quantum communication network between the ground and the satellite, detecting gravitational waves in space, conducting microgravity scientific experiments... With the advancement of science, humans have begun to study the phenomena and laws of physics, chemistry, and even life occurring in the solar-terrestrial space, interplanetary space, and the entire universe. In this regard, space science experimental satellites have an irreplaceable position and role.

Mozi

On August 16, 2016, the world's first quantum science experimental satellite "Micius" was launched into space. It has made breakthroughs in a series of high-precision and cutting-edge technologies, including satellite-ground optical path alignment, polarization state maintenance and satellite-ground vector correction, quantum light source payload, etc., and successfully completed the three major scientific experimental tasks of quantum entanglement distribution, quantum key distribution, and quantum teleportation. On this basis, "Micius" has completed the docking with the "Beijing-Shanghai Trunk Line" and realized intercontinental quantum secure communication. At present, relying on "Micius", Chinese scientists have successfully achieved satellite-ground quantum key distribution across 4,600 kilometers, and have also built the world's first satellite-ground quantum communication network, covering 32 nodes in 4 provinces and 3 cities in my country, including 4 quantum metropolitan area networks in Beijing, Jinan, Hefei and Shanghai, and currently has access to more than 150 users. In addition, "Micius" also provides a new platform for testing basic physics problems such as the fusion of quantum mechanics and gravity.

At the Ali Observatory in Tibet, the "Mozi" quantum science experimental satellite passed by, and researchers were doing experiments (composite photo). Photo by Xinhua News Agency reporter Jin Liwang

"Tai Chi No. 1"

At the end of August 2019, the microgravity technology experimental satellite "Taiji-1" was successfully launched. The displacement measurement accuracy of the laser interferometer carried by "Taiji-1" reached the order of hundreds of picometers (about the diameter of an atom), the measurement accuracy of the gravitational reference sensor reached the order of one billionth of the earth's gravitational acceleration, and the thrust resolution of the microthruster reached the sub-micronewton level. At present, "Taiji-1" has successfully completed all the preset experimental tasks, achieved the highest precision space laser interferometry measurement in my country so far, completed the world's first micronewton-level radio frequency ion and Hall type electric micro-thrust technology full performance verification, and took the lead in achieving breakthroughs in two drag-free control technologies in my country.

This is the "Taiji-1" satellite (photo taken on August 17, 2019). Xinhua News Agency

Tianqin-1

On December 20, 2019, Tianqin-1 was successfully launched into space. The satellite will conduct in-orbit verification of high-precision space inertial sensors, laser interferometers and other equipment, as well as core technologies such as drag-free control technology and micro-Newton propulsion. The results of the first round of experiments showed that all technical indicators of Tianqin-1 exceeded the expected goals of the mission. Recently, the Tianqin-1 satellite has obtained global gravity field data, which can serve the fields of geodesy, geophysics, oil and gas resource exploration, and help to cope with global climate change and disaster prevention and mitigation.

"Huairou No. 1"

On December 10, 2020, the Gravitational Wave Burst High-Energy Electromagnetic Counterpart All-Sky Monitor Satellite ("Huairou-1") was successfully launched. The first two small satellites are distributed on both sides of the earth, using a conjugate orbit constellation layout. They will monitor all-day high-energy celestial burst phenomena such as gravitational wave gamma-ray bursts, fast radio burst high-energy radiation, special gamma-ray bursts and magnetar bursts, aiming to crack the formation and evolution of compact celestial bodies such as black holes and neutron stars, as well as the mystery of the merger of double compact stars. In addition, "Huairou-1" will also detect high-energy radiation phenomena in the Sun-Earth space such as solar flares, terrestrial gamma-ray flashes and terrestrial electron beams, providing scientific observation data for further research on their physical mechanisms. On January 20, 2021, the "Huairou-1" satellite team issued an observation notice for the celestial burst event GRB 210119A in the International Gamma-ray Burst Coordination Network for the first time, marking the beginning of the satellite's provision of timely observation results to the international astronomical community.

(Photo source: Xinhua News Agency)

Reporter: Zhang Ye

Source: Science and Technology Daily