“Drilling two meters deep for sampling will be a world first,” said Hou Zengqian, China’s chief scientist on the Tianwen-3 mission, in a recent interview with China Science Daily. That one sentence expresses the swagger and technical hubris of China’s Mars sample return mission, now set to upset decades of American and European dominance of planetary exploration.
Tianwen-3, which will launch twice in 2028 on Long March 5 rockets, has a pragmatic, engineering-oriented architecture. It will send a lander and ascent vehicle to Mars in one launch, and an orbiter and Earth-return capsule in another. This dual-mission profile, as announced by chief designer Sun Zezhou, builds on China’s recent achievements in lunar sample returns and the landing of the Zhurong rover in 2021, which proved the application of massive supersonic parachutes, accurate guidance, and controlled retropropulsion within the thin Martian atmosphere proved technologies.
The lander will aim for a low-elevation location in the planet’s northern midlatitudes areas such as Utopia Planitia or Chryse Planitia where the thicker atmosphere helps with deceleration during entry, descent, and landing (EDL). There are engineering requirements that require altitudes at least three kilometers lower than Mars’ average, slopes less than 8°, and little rock abundance for safe landing. These selections, although restricting access to geologically richer sites such as Jezero Crater, maximize the chances for mission success.
Sampling tactics are where Tianwen-3 is set to make history. The lander will use three techniques: surface scraping, two-meter deep drilling, and, in a salute to NASA’s Ingenuity, a helicopter drone that can obtain samples 100 meters away from the primary location with minimal contamination risk. The multi-pronged strategy guarantees a variety of materials surface regolith, subsurface rocks, and remotely obtained specimens are sent back for examination. The two-meter drilling depth is particularly significant, as it targets material shielded from harsh surface radiation, potentially preserving fragile organic molecules or isotopic biosignatures.
Astrobiology sits at the heart of Tianwen-3’s scientific objectives. The mission’s framework, detailed in a Nature Astronomy paper by Zengqian Hou and colleagues, is structured around four pillars: where to collect, what to collect, how to collect, and how to analyze. Target sites are chosen not only for engineering safety but also for their ability to protect evidence of previous habitability ancient lakes, deltas, or hydrated mineral deposits with biosignature potential. Returned samples will be examined for molecular, isotopic, and fossil biosignatures, by means of sophisticated methodologies such as mass spectrometry, Raman spectroscopy, and high-resolution imaging. Detection of biogenic isotope fractionation e.g., changes in carbon, sulfur, or nickel isotopes may provide strong proof of ancient life, since these trends are hard to reproduce by abiotic means.
After the ascent vehicle brings its precious load into Mars orbit, an unmanned rendezvous with the orbiter will be a replay of China’s Chang’e-5 lunar sample return but complicated by Mars’ atmosphere and prolonged communication lag. The return capsule, based on China’s new-generation crew spacecraft, is designed for high-velocity, high-temperature reentry into Earth, with planetary protection guidelines strictly enforced. A special Mars sample laboratory in Hefei will separate and examine the material, with “comprehensive biochemical and pathological testing under strict isolation from the Earth’s environment,” according to the University of Hong Kong to avoid biosafety risks.
Conversely, NASA and ESA’s Mars Sample Return (MSR) mission, while more scientifically robust on paper building off Perseverance’s carefully selected samples from Jezero Crater and sophisticated EDL technologies such as Terrain-Relative Navigation and supersonic parachutes has been plagued by delays, cost overruns, and architectural complexity. An independent review estimated MSR at $8–11 billion, with a probable sample return date being pushed into the 2040s owing to organizational and technical challenges. NASA’s recent shift towards industry-sponsored options, such as those proposed by SpaceX and Lockheed Martin, highlights the need to catch up again and not let leadership slip away.
Although some critics, such as planetary geologist Steve Ruff of Arizona State University, point out that Tianwen-3’s engineering limitations reduce its access to comparably compelling samples as those collected by Perseverance, the mission’s incremental, realistic planning could be more robust against political and technological adversity than NASA’s more ambitious schedule.
The prize is gigantic. As Mahesh Anand of the Open University noted, “This is exactly what we have been recommending over the years: to look for any signs of biogenic activity or even just to understand that there was a habitable environment.” The country that returns samples from Mars first will not only explore the history of Mars but also set the world agenda for planetary science and the search for extraterrestrial life.
