International Space Station (ISS): A Home in Space and Stepping Stone to the Moon

 High above our heads, quietly orbiting Earth, a group of people are living one of the most extraordinary lives imaginable. The International Space Station (ISS) isn’t just a scientific laboratory—it’s a second home to astronauts who spend weeks or even months floating in microgravity. But what is life really like up there? In this post, we take you inside the ISS to explore its unique living spaces, daily routines, and how astronauts manage to turn a cold metal station into a place that feels a little like home—millions of miles away from their loved ones.

The International Space Station (ISS) is humanity’s most ambitious space laboratory, orbiting Earth at about 400 km altitude and serving as a testbed for science, technology, and international cooperation. From its origins in Cold War–era plans to its continuous habitation since November 2000, the ISS brings together NASA, Roscosmos, ESA, JAXA, and CSA in a shared mission to advance knowledge and prepare for future exploration beyond low Earth orbit. Onboard, astronauts live much like on Earth—eating balanced, pre‑packaged meals, sleeping under carefully controlled lighting, and staying connected via satellite relays—all while conducting hundreds of experiments that deepen our understanding of biology, materials, and Earth systems. Looking ahead, lessons from the ISS guide designs for lunar orbit stations (Gateway) and surface bases on the Moon, laying the groundwork for sustainable presence on other worlds.

Why, When, and Who Made the ISS a Reality?

The ISS grew from two separate Cold War projects—NASA’s Space Station Freedom and the Soviet Mir‑2 station—merged in 1993 to form a single international program. 

The first module, Zarya (“sunrise” in Russian), was launched by Roscosmos on November 20, 1998, providing propulsion, power, and communications to the emerging station. Two weeks later, NASA’s Unity node arrived aboard Space Shuttle Endeavour, linking U.S. and Russian segments and enabling further expansion. Since November 2, 2000, Expedition 1 has maintained continuous human presence, making the ISS the longest‑running inhabited outpost in space. 

What Is the International Space Station (ISS)?

The ISS is a modular research laboratory divided into the Russian Orbital Segment (ROS) and the U.S. Orbital Segment (USOS), with contributions from ESA, JAXA, and CSA. 

Orbiting Earth every 93 minutes, it travels at roughly 28,000 km/h, allowing crews to witness 16 sunrises and sunsets each day. Its pressurized modules house laboratories, living quarters, and an airlock for spacewalks, while an integrated truss supports solar arrays that generate up to 120 kilowatts of power. Canada’s contributions—Canadarm2, Dextre, and the Mobile Base System—enhance robotic assembly and maintenance capabilities on the station.

Life on ISS: Food, Sleep, Communication

Food

Astronauts choose menus from over 200 items, with diets formulated to meet 100 % of daily vitamin and mineral requirements by NASA’s Space Food Systems Laboratory. Fresh fruits and vegetables, highly prized for taste and nutrition, arrive on resupply vehicles but remain limited by storage life and refrigeration constraints. 

Sleep

Microgravity and 16‑daylight‑hour cycles disturb circadian rhythms, so the ISS uses tunable LED lighting to mimic natural light patterns—bright white for work and reduced blue light before sleep. Crew members allot eight hours for rest within sleeping quarters that are essentially small “cabins” with privacy curtains and ventilation to remove exhaled carbon dioxide.

Communication

The ISS relies on NASA’s Tracking and Data Relay Satellite System (TDRSS) to transmit voice, video, and data between the station and mission control, ensuring real‑time operational links and personal calls home. Advanced optical communication tests, including laser links, aim to boost data rates by 10–100× to support high‑definition livestreams from future lunar and Mars missions.

ISS Research and Experiments

The ISS hosts over 4,000 scientific investigations spanning biology, physics, Earth science, and technology demonstrations.

 •  Human Physiology : Studies bone density loss, muscle atrophy, and immune system changes to inform countermeasures for long‑duration missions.

•  Materials Science: Observing fluid behavior and crystal growth in microgravity leads to improved manufacturing processes on Earth.

•  Earth Observation: Instruments monitor climate change, natural disasters, and urban expansion, providing data for environmental policy and disaster response. 

Concepts of Space Stations and Moon Bases

Lunar Gateway

As part of NASA’s Artemis programme, ESA is building the Gateway—a small station in lunar orbit that will serve as a staging point for crewed Moon landings and deep‑space research.

Lunar Surface Habitats

JAXA envisions a polar Moon base capable of supporting astronauts for six‑month stays, advancing technologies for closed‑loop life support and in‑situ resource utilization. Collective efforts aim to develop soil processing, energy generation, and habitat modules that draw on ISS lessons to ensure sustainable operations on the lunar surface and beyond.

These projects represent the next steps in human space exploration, building upon the knowledge and experience gained from the ISS.

The International Space Station stands as a testament to what humanity can achieve through collaboration and innovation. As we continue to explore space, the lessons learned from the ISS will guide the development of future habitats on the Moon, Mars, and beyond.