Satellites have played an integral part in space exploration and will continue to do so in the foreseeable future. Here’s a short history of how the technology has shaped the industry and where it’s headed.
What is a satellite?
You may think of a satellite as the complex hunk of metal floating around the earth that beam down your 500 television channels. However, “satellite” is actually an extremely broad term, encompassing any object in space that orbits a larger object. There are two categories of satellites:
- Natural satellites. Our moon and those that orbit other planets are natural satellites. The planets themselves technically fall into this category as well since they orbit the sun.
- Artificial satellites. These are the manmade objects you’re thinking of. They have many uses, such as for telecommunications and for observational or exploratory purposes.
This article discusses the artificial variety. There are four main components to any usable artificial satellite, not including the rockets it takes to get into orbit.
- Power system. Depending on the purpose of the satellite, this could be nuclear, solar or battery-based. Nuclear and solar power systems are used when the satellite needs to function for long periods of time (think years or decades).
- An antenna system transmits radio waves and communications to Earth. This enables the ground administrators to receive data the satellite has gathered and control its movements or functions.
- Altitude control. In orbit, a satellite needs a way to make small movements and reorient itself. This is done through the use of magnetic, gyroscopic or gas propulsion systems.
- Components such as sensors, cameras, particle detectors, gauges, telescopes and other electrical equipment make up the payload, which is used to capture the measurements and information a satellite is built to obtain.
A brief history of satellites in space exploration
Here is a short, non-comprehensive history of satellites used to explore the cosmos. Please note that many famous space missions will not be included, such as the Voyager probes. The Voyager craft were sent into space on fly-by missions and never orbited another celestial body, and therefore are not technically satellites.
- Sputnik 1: Oct. 4, 1957, USSR.The Soviet Union launched the first artificial satellite into Earth’s orbit and started a space race that culminated with the U.S. moon landing in 1969. This 183-pound spherical satellite transmitted for 22 days and fell back into the atmosphere in early 1958.
- Explorer 1: Jan. 31, 1958, USA. Less than six months after the successful Sputnik launch, the United States launched its own Earth orbiter, the Explorer 1. It was much lighter, at only 30 pounds, but was responsible for the discovery of the Van Allen Belts.
- Lunar Orbiter Program: Oct. 1966-Jan. 1968, USA. This multi-orbiter program circled the moon and took thousands of high-resolution photos. They mapped the surface of the moon so that a suitable landing spot could be found for the upcoming Apollo missions.
- Viking 1 Orbiter: June 19, 1976, USA. Viking 1 is notable for carrying and successfully deploying the first Mars lander, but that’s not all that’s interesting about the mission. The accompanying orbiter made nearly 1,500 trips around the red planet and sent over 57,000 images to Earth.
- Venera 15 Orbiter: June 2, 1983, USSR. While the United States focused on Mars, the Soviet Union sent multiple Venera missions to Venus. The Venera 15 orbiter made 260 journeys around the hot yellow planet and took detailed synthetic aperture radar (SAR) images. This radar imager was the first to cut through the dense atmosphere of Venus and map out its topology.
- Galileo: Oct. 18, 1989, USA. After a six-year journey to the outer solar system, Galileo entered Jupiter’s orbit in late 1995. It studied Jupiter and many of its mysterious moons. It was the first to discover Io’s volcanism and supported the theory that there may be a vast ocean underneath Europa’s icy outer layer.
- Hubble Space Telescope: April 24, 1990, USA. Chances are if you’ve seen a majestic picture of a faraway nebula, the image was taken by the Hubble Space Telescope. It still orbits the Earth and is in use today.
- Cassini: Oct. 15, 1997, USA. Cassini ventured even farther into the solar system and spent years in orbit around Saturn. It studied the planet’s rings, atmospheric conditions and much more. It also imaged Saturn’s moons, including the Earth-like Titan with its oceans of methane.
- Messenger: Aug. 3, 2004, USA.This craft was the first to orbit Mercury, the closest planet to the sun. It provided many interesting insights, such as the fact that there are ice-filled craters along the planet’s north pole. Previously Mercury was thought to be completely scorched.
- Dawn: Sept. 27, 2007, USA. Dawn is notable for being the first spacecraft to orbit a dwarf planet (Ceres) in the outer solar system. It also utilized a new type of propulsion called ion propulsion, which allowed it to enter and leave the orbits of two different space bodies.
The future of satellites for space exploration
While Explorer 1 was lightweight, most of the subsequent orbiters and spacecraft weighed thousands of pounds (or multiple tons). This makes it extremely expensive to launch them into space.
One solution that seems to be gaining traction is the proliferation of small clusters of lightweight satellites called CubeSats. Whereas previously the electronic equipment needed to perform real science experiments on spacecraft needed to be fairly large and heavy, the miniaturization of technology allows these 4-inch cubes to wield powerful calculating abilities. After all, a modern cell phone has around 100,000 times more processing power than the guidance computers for the Apollo missions!
The shrinking of satellites, combined with the recent advances in rocket science thanks to private companies such as SpaceX, means that sending satellites into orbit or into outer space will become much cheaper. It’s an exciting time for space exploration!
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