China is emerging as a major contender in exploring the Solar System with plans to explore it from Venus to Neptune within the next two decades targeting habitability and extraterrestrial life. It is an ambitious plan requiring proven technology and developing new to carry out the most difficult missions. If it succeeds, there could many firsts.

The bold strategy begins at Mars with China’s Deep Space Exploration Laboratory (DSEL) with a planned sample return mission; Tianwen-3 is already approved, developed, and being built with a launch planned during late 2028. The main objective is to investigate potential traces of past or present life on Mars. The goal is to return no less than 500 grams (at least one pound) of Martian samples to Earth around 2031. The mission will involve two launches, an orbiter and a lander, which will take at least 7 to 8 months to reach Mars. It will operate on Mars for about a year and then return to Earth. The entire mission will last over three years. Three sampling methods will be used to ensure sample diversity and scientific value: surface scooping, deep drilling, and drone-assisted collection. There will be no rover as the drone will collect samples up to several hundred feet from the landing site. The drill will penetrate around six feet into Mars for one of the sample collections. NASA’s Perseverance rover collected shallow samples that rely on a follow-up mission to return them to Earth but is over budget and facing serious delays. Tianwen-3 aims to accomplish both sampling and return in a single mission. Strict measures will be required to avoid contamination of the samples by the spacecraft and contamination of Earth’s biosphere by the Martian samples. The samples will be carefully sealed on Mars and transported and analyzed on Earth. A high-security Mars sample laboratory will be constructed that will feature ultra-clean and biosafety areas where returned samples will undergo strict sterilization, unsealing, processing, and biological risk assessment. China plans to establish a Mars research station around 2038 focusing on conducting long-term Martian environmental and biological research on site. There is no indication the facility will host a crew.

The next mission approved and under development is Tianwen-4, a Jupiter-Callisto orbiter mission scheduled to launch September 2029. The mission was original planned with two probes, one to study Jupiter and Callisto, and the other to separate at Jupiter and head to Uranus for a flyby. Plans keep changing for this mission as the Uranus option was dropped in favor of a more intensive exploration of Callisto. The spacecraft is scheduled to arrive at Jupiter in December 2035 and go into orbit with a period of 30 days. It will then go into orbit around Callisto in February 2038 orbiting once every 17.7 hours and coming as close as 180 miles. It could deploy a penetrator to impact the surface or a soft lander. In addition to the dedicated exploration of Callisto, the goals of Tianwen-4 are to study Jupiter’s magnetic field and plasma, the composition of the atmosphere, and the environment around Io, Europa, Ganymede, and Callisto.

A mission to collect particles from the atmosphere of Venus and return them to Earth is being planned. It has yet to be approved, hence it cannot be given a Tianwen designation, but could launch in 2033. The mission will carry a sample collection device to collect cloud particles, droplets, and if lucky, particles ejected into the clouds from volcanoes far below. The probe might be a plane or drone according to the latest design concept and will also look for phosphine and any indication of life. The temperature and pressure are more like Earth within the clouds around 40-50 miles above the surface but becomes broiling hot just below the cloud deck with crushing pressure. The probe will not land but will still have to be designed to withstand some heat, pressure and especially sulfuric acid. The mission aims to answer key questions about the potential of life on Venus, if it was habitable in the past, the evolution of the atmosphere, and the mystery of the ultraviolet absorber that creates the dark patches in the clouds when Venus is viewed in ultraviolet. The interest is partially due to a controversial study in 2020 of traces of phosphine discovered in the atmosphere, a possible indication of a biological process.

China is successfully developing deep space technology that will help support and advance its deep space exploration program as it plans for its first ice giant mission to orbit Neptune and study Triton, possibly launching around 2039. After arriving at Neptune, the spacecraft would deploy an atmospheric entry probe into Neptune’s atmosphere. It would then observe the rings, moons, magnetosphere, and assess the potential habitability of Triton’s subsurface ocean. Neptune was chosen over Uranus as it holds a greater scientific significance due to its potential implications for understanding extraterrestrial life. Triton is the lure and its active nitrogen geysers could possibly be sampled during very close flybys as it possesses a very thin but very deep atmosphere (around 500 miles). If approved and successful, the mission will likely be the first orbiter mission to Neptune or Uranus, both Ice Giants due to their abundance of water ices and other ices. NASA’s Uranus orbiter mission remains in limbo due to budget problems and a shortage of Plutonium 238 which is needed to power the spacecraft. It could launch later in the 2030’s in a true race to see which country will reach an ice giant first. Neptune gets all the love while Uranus seems to be ignored; a return to Neptune was even considered in the early 1990’s with an orbiter/probe. It would have launched in July 2002 and arrived at Neptune in May 2021 after a 19-year journey, but sadly, it was never funded. Imagine the wealth of images, data, and new knowledge we would already have.

Enceladus is now in the crosshairs of worlds that China plans to explore. This tiny moon of Saturn, only 311 miles in diameter, has active geysers erupting from an underground ocean of liquid water that may contain the chemical ingredients needed for life and is an enticing target because the ice shell is rather thin and accessible, especially near the south pole where the geysers are located. China would use a three-part spacecraft: an orbiter to globally map Enceladus, a lander to make onsite measurements, and a drilling robot that could drill up to three miles below the icy shell to directly sample the ocean and look for life. This may seem ambitious, but China has proven engineering capabilities and a deep space network. Challenges at Enceladus include drilling for miles in the -290ºF environment, but engineers are already proposing a hybrid laser and thermal drilling system to avoid melting the ice too quickly and damaging the spacecraft while at the same time harnessing the heat to melt the ice. It would avoid problems with mechanical wear and debris. This mission would strengthen China’s future planetary exploration processes, advance the understanding of the habitability of icy worlds, planetary formation, the potential for life in the Solar System, and the origin of life itself while enhancing China’s technological capabilities in deep space and its leadership in planetary exploration. Tianwen means “heavenly questions.” China is reaching into the heavens to ask these questions and to seek answers that will come with patience and dedication.