China has greenlit four aspiring new space science missions – Kuafu 2, Hongmeng, Earth 2.0, and eXTP – representing a meaningful expansion of the Chinese Academy of sciences’ (CAS) autonomous space program. These projects, formally approved in recent months as part of the nation’s 15th Five-Year Plan, demonstrate a growing emphasis on cutting-edge astronomical and space physics research. The missions, distinct from those managed by the China National Space Governance (CNSA), adopt a flexible, university-driven model akin too NASA’s Discovery program, promising a new era of scientific exploration for the world’s third-largest country by area.
China has formally approved four new space science missions slated for launch over the next five years: Kuafu 2, Hongmeng, Earth 2.0, and eXTP. The projects represent a growing trend within the Chinese space program, with the Chinese Academy of Sciences (CAS) increasingly developing and launching its own independent missions.
CAS missions operate somewhat independently from projects overseen directly by the China National Space Administration (CNSA) or those prioritized by the China Aerospace Science and Technology Corporation (CASC), such as the Chang’e and Tianwen programs. Instead, these missions are proposed based on the needs of research teams across the country’s institutes and universities, mirroring a model similar to NASA’s Discovery program of low-cost missions. This decentralized approach allows for greater flexibility and responsiveness to emerging scientific questions.
While these missions weren’t entirely unexpected – development of eXTP, for example, dates back to before 2018 – their formal approval marks a significant step forward. The Hongmeng Project (鸿蒙计划, ‘harmony’ in Mandarin), also known as DSL (Discovering the Sky at the Longest Wavelength), will deploy a constellation of ten satellites in lunar orbit. Unusually, these satellites won’t study the Moon itself, but rather the “dark ages” of the universe – the period between the recombination era and the formation of the first stars, roughly 100 million years after the Big Bang.
The expansion of the universe has redshifted the 21-centimeter wavelength emitted by hydrogen atoms during this era, resulting in extremely long wavelengths with frequencies between 10 and 40 MHz. This radio frequency range is heavily impacted by human-generated interference, making the far side of the Moon an ideal location for observation. The project aims to unlock insights into the universe’s earliest stages, a key area of cosmological research.
The Chang’e 4 probe, the first spacecraft to land on the far side of the Moon, carried an experiment to detect this radiation, along with the Queqiao satellite. Several instruments and missions are planned to follow in the coming years. Hongmeng will consist of a 620 kg main satellite and nine subsatellites in a 300-kilometer lunar orbit at a 30-degree inclination, using interferometry to observe radiation from the far side.
Of the subsatellites, eight will weigh approximately 75 kg and observe the sky at frequencies of 0.1 to 30 MHz, while one will operate at frequencies of 30 to 120 MHz. The mission’s design leverages a distributed network of sensors to maximize data collection and sensitivity.
Kuafu 2 (夸父二号) or the Polar Orbiting Solar Observatory (太阳极轨天文台) – SPO – will be a solar observatory designed to directly study the Sun’s polar regions, complementing observations from the European Solar Orbiter mission. Scheduled for launch in 2029, Kuafu 2 will operate in a solar orbit between 0.9 and 1.15 Astronomical Units (AU) and achieve an inclination of over 80 degrees to view the polar regions. Like the European Ulysses probe, Kuafu 2 will perform a Jupiter flyby to achieve its highly inclined solar orbit, followed by multiple Earth flybys for orbital adjustments. Notably, Kuafu 2 will be China’s first spacecraft to visit Jupiter, with a planned flyby in 2032, two years before the Tianwen 4 probe.
The spacecraft will carry nine instruments, including the 0.5 to 10 keV X-ray telescope XIT, two coronagraphs (VLACOR and VISCO), the EUST ultraviolet telescope, the MHI camera for studying the Sun’s magnetic field (with a resolution of 0.5 to 1 arcsecond per pixel), a low-frequency radio spectrometer, a magnetometer, and two particle detectors (SWIA and SEPA). Kuafu 2 is expected to operate for at least one solar cycle – 11 years – providing a wealth of data for solar physics research.
The Earth Two (ET) observatory, also known as Earth 2.0 (地球2.0) or 系外地球 (xìwài dìqiú, ‘exoplanet’ in Mandarin), or more recently, ‘exoplanet explorer’ (系外地球巡天), is a mission previously covered on this blog. Similar to the European Space Agency’s PLATO mission, it will consist of six wide-field telescopes with a 28-centimeter aperture and a 550-square-degree field of view each (PLATO has 26 cameras) to discover planets using the transit method. It will also include a 35-centimeter telescope with a 4-degree field of view to detect extrasolar planets using gravitational microlensing by observing approximately 30 million stars in the galactic center region.
The six main telescopes will observe approximately two million FGKM-type stars during the four-year primary mission. Each telescope includes a camera cooled to -40°C with four GSENSE1081 type CMOS sensors with 8900 x 8210 pixels. Earth 2.0 is expected to discover more exoplanets than PLATO – up to twenty, compared to the two or three expected from the European observatory – due to its continuous observation of the same area of the sky, mirroring NASA’s Kepler mission. The mission is slated for launch in 2028 and will be positioned at the L2 Lagrange point of the Earth-Sun system.
Finally, the eXTP (Enhanced X-ray Timing and Polarimetry) observatory, scheduled for launch in 2027, includes significant European collaboration from Italy, Germany, Switzerland, Spain, France, Denmark, the Czech Republic, and the Netherlands. It features four main instruments with high temporal resolution to analyze high-energy radiation from compact objects like black holes and neutron stars, validating their properties and testing current models. These instruments operate in the 0.5 to 10 keV energy range and include the SFA (Spectroscopic Focusing Array) spectrometer, the PFA (Polarimetry Focusing Array) polarimeter, and the LAD (Large Area Detector) and WFM (Wide Field Monitor) detectors. The observatory will be placed in an elliptical orbit 110,000 kilometers from Earth.
These CAS missions are part of the 15th Five-Year Plan and were officially selected in 2024 from a pool of competing proposals, receiving final approval more recently. While China’s scientific space program still lags behind those of the European Space Agency (ESA) and NASA, it has made rapid progress in recent years. However, CAS missions have experienced delays, cancellations, and restructuring, indicating ongoing adjustments to their integration within the country’s broader space program.
