THE RETURN TO SELENE: THE ARTEMIS PROGRAM – PAST, PRESENT AND FUTURE

More than fifty years after Apollo, humanity has begun its journey back to the Moon. Through the Artemis Program, NASA and its international partners are laying the foundations for a sustained human presence on the lunar surface while preparing for future missions to Mars. This article explores the past, present, and future of one of the most ambitious space exploration programmes ever undertaken.
(Translation of the paper “De Apollo a Artemis: a história, a tecnologia e os próximos passos do programa que levará a humanidade de volta à Lua”, originally published in The Conversation Brasil.)

Authors: Rodrigo Siqueira-Batista; Ricardo Alves Ferreira; & Thais Russomano

Author names link to their LinkedIn profiles.

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Human activity on the Moon, Selene for the ancient Greeks, constitutes one of the most significant chapters in scientific history. Between 1968 and 1972, the Apollo program, conducted by NASA (National Aeronautics and Space Administration), took twelve astronauts to the lunar surface, beginning with the Apollo 8 mission, the first crewed mission to orbit the Moon, and culminating with Apollo 17. These missions not only demonstrated humanity's technological capabilities but also provided crucial scientific data on lunar geology, the formation of the Earth-Moon system, and the history of the Solar System itself.
However, after 1972, human exploration of the Moon came to an end, marking the beginning of a hiatus that has now lasted more than five decades.
This prolonged interval reflected geopolitical changes, shifting economic priorities, and technological challenges. Nevertheless, fascination with Selene remained alive, both as a scientific destination and as a strategic platform for future interplanetary missions. In the twenty-first century, with advances in technology and increasing international cooperation, NASA launched the Artemis program. With Artemis I and Artemis II now successfully completed, its objective is not only to return to the Moon, but also to establish a sustainable human presence there.

The Artemis I Mission: The Past
Conceived as the cornerstone of the Artemis Program, the Artemis I mission represented the first major integrated test of the systems designed to take humans back to the Moon. Launched on 16 November 2022 (Figure 1) aboard the Space Launch System (SLS) rocket, the mission carried no astronauts. Instead, Orion flew with the instrumented mannequins Commander Moonikin Campos, Helga, and Zohar, equipped with sensors capable of recording the radiation and acceleration conditions to which future astronauts would be exposed in the space environment.
During a journey of approximately 25.5 days, Orion travelled more than 2.25 million kilometres, entered a distant retrograde orbit around the Moon (Figure 2), and reached a maximum distance of 432,210 kilometres from Earth, the greatest ever achieved by a spacecraft designed for human transport, before returning and splashing down safely in the Pacific Ocean on 11 December 2022.

Figure 1. The SLS rocket and Orion spacecraft lift off from Launch Complex 39B at Kennedy Space Center on 16 November 2022. Source: NASA.

Throughout the mission, Orion's heat shield, life-support systems, the propulsion system of the European Service Module (ESM) developed by the European Space Agency (ESA), and its long-range communication systems were thoroughly tested and validated. The critical re-entry phase, during which the capsule reached speeds close to 40,000 km/h and temperatures of up to 2,760°C on the surface of its heat shield, was successfully completed, confirming the robustness of the AVCOAT ablative coating, one of the most critical elements for ensuring the safety of future crews.
Although post-mission analyses identified slightly higher-than-expected erosion in some regions of the heat shield, these findings proved invaluable for improving the system before the first crewed flight.

Figure 2. Orion in distant retrograde orbit around the Moon during Artemis I. Source: NASA.

From a scientific perspective, Artemis I provided a valuable dataset on the radiation environment in deep space, essential for protecting future crews. The dosimeters installed on the mannequins showed that astronauts will be exposed to significantly higher radiation doses than those experienced during missions in low Earth orbit, reinforcing the need for mitigation strategies already incorporated into the planning of subsequent Artemis missions.
More than a technological demonstration, Artemis I established the benchmark against which the entire Artemis Program would be evaluated, proving that a human return to the Moon was not only desirable but also technically feasible, thereby laying the foundations for the first crewed mission that would follow.

The Artemis II Mission: The Present
Building on the foundations established by Artemis I, the Artemis II mission was the second major step in the Artemis Program and the first with a crew on board. Conducted in April 2026 over approximately ten days, its central purpose was to validate, under real flight conditions, systems previously tested only in simulated or uncrewed environments: life support, navigation, communication, propulsion, and human performance in deep space. More than a journey around the Moon, Artemis II was a decisive and successful test of the viability of this new paradigm of human activity in space, delivering a rich set of physiological and operational data fundamental to the planning of subsequent missions.
The mission used the powerful Space Launch System (SLS) rocket to place the Orion spacecraft on a translunar trajectory (Figure 3). Named Integrity by the crew themselves, a name embodying the values of trust, respect, and humility that united the four astronauts and the thousands of professionals from many nations involved in the project, the spacecraft was powered by the European Service Module (ESM), developed by the European Space Agency (ESA) with significant participation from Airbus Defence and Space.

Figure 3. Orion spacecraft during the Artemis II mission. Source: NASA.

This European module, equipped with 33 engines and four large solar arrays, functioned as the "heart" of the spacecraft, providing propulsion, electrical power, and life support throughout the journey, a concrete example of the international cooperation that distinguishes the Artemis Program. At the controls of Integrity was a crew composed of Reid Wiseman (Commander), Victor Glover (Pilot), Christina Koch, and Jeremy Hansen (Mission Specialists), a historic team that, for the first time, included a woman, an African American astronaut, and a Canadian representative on a mission beyond low Earth orbit (Figure 4).

Figure 4. The Artemis II crew: Reid Wiseman, Victor Glover, Christina Koch, and Jeremy Hansen. Source: NASA.

The trajectory followed the free-return trajectory, in which the Moon's orbital dynamics guarantee a safe return to Earth even in the event of a propulsion failure, the same strategy that safeguarded the most critical Apollo missions. After launching from the Kennedy Space Center on 1 April 2026, Orion completed its translunar injection on the second day and continued towards the Moon. On 6 April, it reached a record distance of 248,655 miles from Earth, surpassing the historic mark set by Apollo 13. On the same day, the crew also observed a spectacular solar eclipse (Figure 5). During the fly-by of the far side of the Moon, the astronauts experienced approximately three hours of communications blackout, a period used for autonomous observations, unprecedented photographic records of the Orientale Basin and Pierazzo Crater, and observations of unexpected shades of green and brown, suggesting mineralogical variations within the lunar crust.

Figure 5. "Solar Eclipse of the Heart" (6 April 2026). The Moon, illuminated by the Sun during a solar eclipse, photographed by one of Orion's solar array cameras. Earthlight illuminates the Moon's left-hand edge, while Saturn and Mars are also visible. Source: NASA.

In parallel, the crew conducted pioneering human health experiments, including ARCHeR, the immune biomarker protocol, Standard Measures, and AVATAR (organ chips derived from the crew members themselves). These investigations collected valuable data on sleep, stress, immunity, the microbiome, and the effects of cosmic radiation on living human tissues, information that will be crucial for planning future missions to Mars.
The mission culminated in splashdown in the Pacific Ocean on 10 April 2026, approximately 200 kilometres off the coast of San Diego. Atmospheric re-entry, performed at speeds exceeding 11 km/s and temperatures approaching 3,000°C, confirmed the robustness of Integrity's heat shield. Specialist teams from the United States Navy, operating from the recovery ship USS John P. Murtha, safely recovered the four astronauts, who emerged emotional and in excellent health. Hours later, after being transferred to the Johnson Space Center in Houston, they began the protocols for readaptation to Earth's gravity and the technical and scientific debriefing, bringing to a highly successful conclusion the first human flight beyond low Earth orbit in more than five decades.

The Artemis III and IV Missions: The Future
​Artemis II proved that humans can safely travel beyond Earth's atmosphere, while Artemis III (Figure 6) will have an equally crucial, yet distinct, mission. Scheduled for mid-2027 in low Earth orbit, it will be the first operational docking test between the Orion spacecraft and commercial lunar landing systems: SpaceX's Starship and Blue Origin's Blue Moon.
This demonstration mission is of extraordinary operational complexity. The Space Launch System (SLS) will launch Orion with four astronauts, using a structural spacer in place of the upper propulsion stage, while the commercial lunar vehicles will reach orbit through separate launches. The astronauts will spend longer aboard Orion than during Artemis II, validate Orion's docking system for the first time, and may also enter one of the lunar landing vehicles. In the words of Jeremy Parsons, Acting Deputy Associate Administrator for NASA's Moon to Mars Program, "Artemis III is one of the most complex missions ever undertaken by NASA," because the success of the subsequent lunar landing depends upon it.

Figure 6. The Orion service module for Artemis III undergoing acoustic testing at NASA's Kennedy Space Center Operations and Checkout Facility on 7 May 2026. Source: NASA.

With the docking systems validated by Artemis III, the path opens for the most anticipated stage of the programme: Artemis IV, scheduled for early 2028, which will mark the first human landing on the lunar surface since Apollo 17 in 1972. Four astronauts will travel to lunar orbit aboard Orion. There, two of them will transfer to the commercial Human Landing System (HLS) and descend to the vicinity of the lunar south pole, a region never explored in situ, where uncrewed probes have identified evidence of water in permanently shadowed craters.
​The lunar south pole is of particular scientific interest because permanently shadowed craters are believed to contain water ice, a resource that could support future human exploration by providing drinking water, oxygen, and rocket propellant.
Over the course of approximately one week, the crew will conduct spacewalks using Axiom Space's advanced AxEMU spacesuits, collect unprecedented geological samples, and deploy scientific instruments on the surface, including DUSTER (DUst and plaSma environmenT survEyoR), which will characterise the dust and plasma environment around one of the nine candidate landing regions identified by NASA near the lunar south pole. The mission will also mark the historic moment when the first woman and the first non-white astronaut set foot on the Moon.
More than a return, Artemis IV will lay the foundations for a sustainable human presence on the Moon and represent the first concrete step on a journey that will eventually take humans to Mars.

Synthesis
The Artemis Program, encompassing Artemis I, II, III, IV and the missions that will follow, inaugurates a new era of human activity in space, demonstrating the viability of crewed missions beyond Earth's orbit after more than fifty years. Its achievements will be crucial to the success of the next stages of the Artemis Program, particularly Artemis III, which aims to enable humanity's return to the lunar surface. In addition, the programme establishes the technological and operational foundations required to build a sustainable presence on the Moon and, ultimately, to support future missions to Mars.
The public and inspirational impact of the missions, especially Artemis II, has also been remarkable. Millions of people around the world followed the first crewed flight beyond low Earth orbit in more than fifty years through television, the internet, and social media, rekindling a collective fascination with space and inspiring a new generation of students interested in science, engineering, and exploration.
The Artemis Program represents a remarkable synthesis of tradition and innovation in humanity's exploration of the cosmos. As the heir to the Apollo legacy, it goes beyond merely repeating history by embracing new technologies, unprecedented international cooperation, and ambitious scientific objectives. More than journeys to the Moon, these missions represent a full-scale rehearsal for the expansion of human presence beyond Earth.
May the deities whose names these missions bear, Apollo, Artemis, and Selene, herald not only new chapters in humanity's exploration of space, but also a renewed appreciation of the importance of caring for Earth (Figure 7), our shared home, whose shades of blue continue to cradle every known form of life.

Figure 7. Earth's sunset, photographed from Orion during the Artemis II lunar fly-by on 6 April 2026. The illuminated Earth rises beyond the lunar horizon, reminding us of the fragility and uniqueness of our home planet. Source: NASA.

Why Artemis Matters
Beyond its remarkable engineering achievements, Artemis is also transforming our understanding of human health in deep space. Each mission generates invaluable knowledge on radiation exposure, physiological adaptation, behavioural performance, and operational medicine, helping prepare astronauts not only for sustained exploration of the Moon but ultimately for human missions to Mars.
For the aerospace medicine community, Artemis represents one of the most important research opportunities since the Apollo era. The programme is advancing our understanding of how humans can live and work safely beyond Earth while driving innovations with potential benefits for healthcare on our own planet. As the Artemis missions continue, they will not only shape the future of space exploration but also deepen our understanding of the remarkable adaptability of the human body and mind.