By Wu Weiren
The solar system is home not only to the eight major planets but also to an immense number of
smaller celestial bodies – asteroids and comets – varying in size, shape, and orbital characteristics.
Among them, asteroids are defined as solar-orbiting objects smaller than planets and dwarf
planets, typically inactive in releasing gas or dust. These bodies, numbering in the billions, are
often referred to as "living fossils" of the solar system's formation and evolution. Asteroids with a
perihelion distance of less than 1.3 astronomical units (AU) are categorized as near-Earth asteroids
(NEAs).
NEAs represent one of the most significant potential threats to Earth. The United Nations has
ranked asteroid impacts among the top 20 existential threats to humanity. The prevailing scientific
consensus holds that an asteroid approximately 10 kilometers in diameter was responsible for the
mass extinction event 66 million years ago, which eradicated roughly 75 percent of Earth's
species, including the dinosaurs. More recent examples include the 1908 Tunguska event, which
flattened over 2,000 square kilometers of Siberian forest, and the 2013 Chelyabinsk incident, in
which a meteor explosion injured approximately 1,500 people and damaged some 3,000 buildings.
While the likelihood of such catastrophic events remains low, their potential consequences are
profound. As of March 2025, 38,171 near-Earth objects had been identified, comprising 38,048
near-Earth asteroids and 123 near-Earth comets. However, due to the technical challenges of
detection, only about 1 percent of near-Earth asteroids are currently catalogued. Early in 2025,
asteroid 2024 YR4 briefly showed a 3.1 percent probability of Earth impact, triggering global
concern.
How should we respond to these "uninvited guests"?
At the third International Deep Space Exploration Conference, held recently in Hefei of Anhui
province, Chinese scientists presented their vision for asteroid exploration, planetary defense, and
resource utilization, while extending an open invitation for international cooperation.
The China National Space Administration has in recent years launched a series of feasibility
studies and preliminary programs focused on NEA detection and defense, including a formal
proposal to build a national a near-Earth object defense system. Chinese scientists have outlined a
comprehensive two-pronged strategy: first, the development of an integrated early warning system
that leverages both ground-based and space-based monitoring assets; and second, the
establishment of mitigation capabilities centered on kinetic impactors, supplemented by additional
technologies and supported by a mission response library to ensure that each credible threat can be
addressed with a pre-planned, executable solution.
China aims to conduct its first asteroid deflection demonstration mission around 2027. This kinetic
impact test has three primary objectives: to alter the trajectory of the target asteroid; to observe the
impact in detail, including velocity and energy transfer; and to monitor post-impact changes to
assess the operation's success.
The mission involves targeting a small asteroid approximately 10 million kilometers from Earth,
aiming to change its velocity by 3 to 5 centimeters per second, sufficient to alter its trajectory. The
selected target poses no risk of Earth impact for at least the next century.
From the standpoint of planetary defense and the long-term survival of humanity, developing
asteroid mitigation capabilities is a global imperative. As a responsible major player in space,
China is committed to contributing its expertise and resources to the establishment of an
international asteroid detection and defense system.
Beyond defense, asteroid exploration and resource utilization also hold immense promise.
Asteroids contain significant reserves of iron, nickel, platinum-group metals, and water ice. They
are broadly classified into metallic, carbonaceous, and silicate types. The exploitation of asteroid
resources – long pursued by leading spacefaring nations – holds transformative economic potential.
According to authoritative estimates, over 700 of the roughly 1,000 asteroids studied in detail are
each valued at more than $100 trillion. Over the next 30 years, the projected economic value of
main-belt asteroid resources may exceed $700 quintillion.
This field is not only a strategic pillar of deep-space exploration but also a foundational
component of the emerging extraterrestrial resource economy. With ongoing advances in nuclear
space propulsion, quantum technologies, and embodied intelligence, the development of asteroid
resource is expected to become increasingly intelligent, cost-effective, and commercially viable.
In the future, a large-scale industrial chain centered on asteroid exploitation is likely to emerge,
becoming an integral part of the deep-space economy.
(Wu Weiren is the chief designer of China's lunar exploration program, and the director and chief
scientist of the Deep Space Exploration Laboratory.)
