ElevationProduction: HIRAKAWA Norimichi
On its nearly circular orbit at an altitude of 407km, the art satellite “INVADER” is going to travel at the breathtaking speed of 7.6627km per second, or 27,593km/h, and will thus need only 92 minutes and 42 seconds to make one orbit around the earth. This altitude, at which also the International Space Station (ISS) orbits, lies within a layer of the atmosphere known as the "thermosphere", where gravity is only about 1/100,000th that of the earth's surface, and temperature rises with increasing altitude, up to approximately 1,000 °C. However at this altitude the atmosphere's density is so low that atmospheric pressure is only one billionth that of the earth's surface. Therefore the human body does not sense the high temperature as heat, which makes it possible for astronauts to walk in space.
At Terminal 1 “Elevation,” variously sized objects ranging from daily life articles up to those at the INVADER's altitude of 407km, are displayed on a seamlessly scrollable table. By way of the tiny 10cm CubeSat, visitors can observe how the sense of scale/distance changes according to direction, demonstrated here on the examples of humans, whales, Space Shuttle, ISS, Concorde, Pyramids, Eiffel Tower, Burj Dubai, Large Hadron Collider (LHC), and in addition, Mt. Fuji, Mt. Everest, aircraft, and the altitude of the ISS/CubeSat. The linear distance between Tokyo and Osaka is about 400km. While this distance surely isn't a big deal down here on earth, traveling 400km in vertical direction takes us to a totally different world.
EnvironmentProduction: ONISHI Yoshito
Data contributed by PRISM Project Team, Intelligent Space Systems Laboratory, The University of Tokyo
With states of “high vacuum” that causes the outgassing (release of a gas that was dissolved, trapped, frozen or absorbed) or cold welding (process in which joining takes place without fusion/heating) of materials; microgravity in which floatage triggers short circuits or impedes mobility; high radiation inflicting damage or failure of electronic devices; and in addition, “cosmic dust” and “space debris” flying around, space is an environment with extreme conditions that are hard to imagine on the ground. Looking at the issue of heat alone, between the 6,000 °C hot sun itself and outer space with a temperature close to absolute zero, there are huge temperatures differences, ranging from over 100 °C at places irradiated by the sun, and several dozen degrees below zero at points the rays of the sun don't reach. As we are talking about a vacuum plus microgravity situation, there is no air-cooling, and no convection currents that could mitigate the thermal differences. In order to ensure the normal function of a computer in such kind of environment, and protect the vulnerable rechargeable batteries from high and low temperatures, accurate analysis and simulation, and appropriate design are imperative.
At Terminal 2 “Environment,” the temperature and position of the satellite in orbit, as well as geomagnetic forces and other environmental aspects surrounding the satellite, are being visualized intuitively in chronological order. As it is impossible to follow a satellite in its orbit, even the developers themselves will never be able touch the satellite again once it has been launched. To make the satellite "feel" its environment in as real a manner as possible is one of this project's central themes. The displays at this terminal are based on actual sensor data transmitted from The University of Tokyo's nano-satellite PRISM that is currently in operation.
LocationProduction: ICHIKAWA Sota
Technical Support: doubleNegatives Architecture
Data contributed by PRISM Project Team,Intelligent Space Systems Laboratory The University of Tokyo
INVADER travels the sky in an inclined orbit with an angle of 65 degrees, at a latitude between –65 and +65 degrees. As it is in a polar sun-synchronous orbit and therefore passes a certain position at a different time each day, it will go through periods of permanent solar irradiation, as well as periods during which it will be half irradiated and half hidden from the sunlight, which makes heat and power design extremely tricky tasks.
At Terminal 3 “Location,” the position of the PRISM satellite in relation to the earth's surface and ground station, as well as the satellite's transmissible, visible range are depicted in a Mercator projection based on the satellite's direction of movement and position in relation to the earth on a given day. Here it is possible to observe gradual shifts in the relationship between the satellite's orbit and the earth surface due to the rotation of the earth. Communication between the ground station on The University of Tokyo's Hongo Campus and the satellite will be possible four times each day. While looking at the map based on the satellite, visitors can further experience both visually and acoustically via radio waves how the satellite that cannot be seen with the naked eye moves closer within visible range, and slowly disappears again after the correspondence.
Tama Art University is presently setting up a new ground station for the “ARTSAT: Art and Satellite Project.” Nonetheless, a singular ground station can communicate with a satellite for a total of not much more than 25 minutes per day, which means that the total volume of data exchanged at a speed of 1,200bps between INVADER and the ground station can amount to only 11 kilobytes per day.