Successful Launch of the H3 Rocket
The Japan Aerospace Exploration Agency (JAXA) has successfully launched the H3 rocket number 10, deploying the Martian moon exploration probe known as “MMX” into space. The rocket executed its flight as planned, with the MMX detaching approximately one hour, eleven minutes, and thirteen seconds after liftoff.
MMX is a spacecraft that forms part of JAXA’s ambitious project to explore Mars’ moons. Its primary objective is to land on Phobos, one of the Martian moons, collect over 10 grams of soil, and return it to Earth by 2031. Achieving this would be a groundbreaking milestone for humanity, as no samples have ever been brought back from Mars.
This initiative is a collaborative effort involving international partners, including NASA, the French National Centre for Space Studies (CNES), the German Aerospace Centre (DLR), and the European Space Agency (ESA), with an anticipated duration of around five years. Previous reports have outlined various details regarding the exploration’s objectives, the spacecraft’s design, and the sample collection mechanism.
The Significance of the Mission
The aspiration to retrieve samples from Mars has been a longstanding ambition for the United States. The Mars Sample Return programme, developed by NASA and ESA, aimed to bring back samples collected by the Perseverance rover. However, in 2024, NASA revealed that the overall budget had soared to an estimated $11 billion, pushing the timeline for sample return to 2040.
Moreover, a budget approved in January 2026 indicated a lack of Congressional support, with only $110 million allocated for future missions. The ESA has also announced it will not pursue the plan further, leaving over 30 samples still on Martian soil.
In this context, the upcoming Chinese mission, Tianwen-3, scheduled for launch around 2028, is gaining increasing prominence. The China National Space Administration has outlined plans to return Martian samples to Earth by approximately 2031, intending to collect over 500 grams of material through two separate launches. In September 2026, it was announced that this mission had entered its prototyping phase.
With MMX expected to return to Earth in 2031, it places Japan and China in a competitive race to be the first to bring Martian samples back to our planet. However, their missions have differing goals: Tianwen-3 aims to collect Martian soil, while MMX focuses on gathering sand from Phobos.
Upcoming Milestones and Challenges
The first significant milestone for MMX is its anticipated arrival at Martian orbit, approximately one year post-launch in 2027. Once in orbit around Mars, MMX will release the lander module, which carried fuel and propulsion systems to reach Martian orbit. Subsequently, it will enter a pseudo-orbit, flying close to Phobos to survey its surface and identify a suitable landing site. Out of its planned three years in Martian orbit, around two and a half years will be dedicated to orbiting and observing Phobos.
Before the landing on Phobos, the rover IDEFIX, developed collaboratively by CNES and DLR, will play a crucial role. For about 100 days, IDEFIX will study the surface’s properties and topography, utilising the gathered data to prepare the main rover for landing. According to DLR, the rover is expected to be deployed by late 2028 or early 2029. If successful, IDEFIX would become the first wheeled rover to traverse a Martian moon.
The most significant challenge lies in the landing of the MMX unit. Two landing attempts have been planned. The first will utilise a combination of two methods: a sampler method, which involves using a cylindrical device to collect samples, and a pneumatic method, which uses nitrogen gas injection to dislodge sand from the surface. The second attempt will rely solely on the sampler method.
The Technical Aspects of the MMX Mission
The estimated duration from landing to liftoff is approximately two and a half hours, with around 90 minutes allocated specifically for sample collection. Within this limited timeframe, the probe must execute both descent and ascent autonomously. Additionally, the system is designed to acquire a sample of 10 grams or more in a single collection attempt, although the sampling will occur in two separate phases to ensure a diverse range of samples.
This landing and sample collection process is scheduled for after 2029. Following this, a flyby of Deimos, another Martian moon, will occur before the exploration module separates. In 2030, the return module is expected to exit the Martian sphere of influence and travel towards Earth for approximately one year. Ultimately, it is anticipated that the capsule containing the samples will re-enter the Earth’s atmosphere and be recovered in 2031.
The H3 Rocket’s Journey
The H3 rocket number 10, which launched the MMX probe, is equipped with two first-stage engines and four solid rocket boosters (SRBs). Utilising its “24” configuration for maximum thrust, it propelled the 4,480 kg spacecraft out of Earth’s orbit.
The past year has been one of significant uncertainty for the H3 rocket. On December 22, 2025, the eighth H3 rocket was launched, carrying the quasi-geostationary satellite “Michibiki No. 5.” However, a premature failure during the second stage motor ignition led to the satellite not reaching its intended orbit. This failure cast a long shadow over Japan’s entire space programme.
An investigation by JAXA concluded that delamination occurring during the manufacturing of the satellite mounting adapter likely exacerbated the situation, resulting in damage during the fairing separation. It is believed that some components exceeded the specified temperature during the pre-bonding heating process, compromising the adhesive’s strength. Following the implementation of corrective measures, JAXA resumed launches with the sixth satellite on June 12, 2026, successfully launching the ninth satellite on August 11.
The launch of MMX marks the third successful launch of the H3 since its resumption. While the primary function of the rocket is to place the probe in its designated orbit, sending a spacecraft into deep space approximately ten months after the previous failure represents a significant achievement in restoring confidence in the H3 programme. Thus, the five-year journey of MMX has finally commenced.