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  • Category: Tech

Tianwen-2 is China's first asteroid sample-return and comet exploration mission, launched on May 29, 2025, from the Xichang Satellite Launch Center aboard a Long March 3B rocket . As the second mission in China's Planetary Exploration Program, it aims to achieve a world-first "one mission, two targets" approach: sampling the near-Earth asteroid 469219 Kamoʻoalewa and then exploring the main-belt comet 311P/PanSTARRS .

Mission Targets

The primary target, 2016 HO3 (named Kamoʻoalewa, meaning "oscillating celestial fragment" in Hawaiian), is an Earth quasi-satellite with an estimated diameter of 30–100 meters . It is the closest and most stable quasi-satellite of Earth, orbiting the Sun in near-synchrony with our planet at a distance of about 0.1–0.3 AU .

The secondary target, 311P/PanSTARRS, is a main-belt comet located in the asteroid belt between Mars and Jupiter, exhibiting both asteroid-like orbital characteristics and comet-like activity .

Spacecraft and Payloads

The spacecraft consists of an orbiter and a re-entry capsule, with a total mass of approximately 2,000 kg . It is equipped with circular flexible solar panels and both chemical and ion electric propulsion systems . The probe carries 11 scientific instruments , including:

  • Visible and infrared imaging spectrometers
  • Multispectral and color cameras
  • Thermal emission spectrometer
  • Mass spectrometer
  • Magnetometer
  • Asteroid Interior Structure Detection Radar (AISDR) for probing internal structure
  • Charged and neutral particle analyzers
  • The Italian-built DIANA dust analyzer for detecting volatiles and organic compounds

Mission Timeline

The mission follows a 10-year flight plan :

  • May 2025: Launch and escape from Earth orbit at 11.2 km/s
  • June 2026: Orbit insertion around Kamoʻoalewa
  • July 2026 – April 2027: Close-proximity observations and sample collection using both touch-and-go and anchor-and-attach methods
  • November 2027: Return capsule lands on Earth with samples
  • January 2035: Rendezvous with main-belt comet 311P

The sample capsule is expected to deliver at least 100 grams of regolith for laboratory analysis, contributing to studies on the formation and evolution of asteroids and the early Solar System .