The International Space Station (ISS) is a permanently crewed, multinational space laboratory in low-Earth orbit. Continuously staffed since 2 November 2000, it is the longest-running space station program of all time, and consistently cited among the world's most ambitious engineering projects. Boasting a pressurized volume of 932 cubic meters, the ISS has an interior space equivalent to 24 shipping containers and with regular supply missions can indefinitely host up to 7 crewmembers.
The station is typically staffed by dual 3-person crews assigned to overlapping six-month missions, with each unique complement of 6 people composing a numbered Expedition (each 3-person crew will serve on two Expeditions during their stay). NASA and Roscosmos have also experimented with one-year crews, and may do so again in the future.
In the Integration Building at the Baikonur Cosmodrome in Kazakhstan, ISS crew members Christina Koch of NASA (left), Alexey Ovchinin of Roscosmos (center) and Nick Hague of NASA (right) pose for pictures in front of the Soyuz MS-12 spacecraft March 10 during final pre-launch inspections.
The station is currently between crew rotations and has just 3 astronauts aboard, after the return of Soyuz MS-11 on 25 June 2019. Soyuz MS-13, carrying NASA's Andrew Morgan, ESA's Luca Parmitano, and Roscosmos' Alexander Skvortsov, is scheduled for launch on 20 July 2019.
The station's altitude averages just over 400 kilometers. Earth's atmosphere continually drags it down. Mission controllers reboost its altitude regularly using either engines on the Zvezda service module or on visiting spacecraft. The station’s high, 51.64-degree orbital inclination carries it over 90 percent of the world's population, and its large size and reflective solar panels make it easy to spot from even brightly lit cities. You can sign up to receive text or email alerts from NASA when the station is visible from your location.
The ISS also offers a means of cooperation for five of the world’s major space agencies: NASA, Roscosmos, ESA, JAXA, and CSA. Station astronauts regularly videoconference with students around the world.
Dimensions: 109 meters across the central truss, 73 meters across the pressurized modules
Power: The station’s primary power source is 8 Solar Array Wings (SAWs), each consisting of 2 retractable blankets of dual-sided solar cells. The wings actuate to follow the sun on 2 axes as the station orbits the Earth, capturing both direct and reflected sunlight. The maximum beginning-of-life output of each wing is 31 kW, creating a theoretical max of 248 kW from the entire system. Power from the SAWs is shunted to lithium-ion batteries. There are also smaller solar arrays on the Russian Zarya and Zvezda modules; Zarya supplies an average of 3 kW, while Zvezda supplies a maximum of 13.8 kW.
Time zone: The space station’s official time zone is UTC, a compromise between NASA’s mission control in Houston (CST, UTC-6) and Russia’s mission control near Moscow (MSK, UTC +3).