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65 years have passed since the first artificial satellite was sent into Earth orbit. Modern satellites are produced even in nano format, and in space they perform a variety of functions.
The first artificial satellite was launched into Earth orbit on October 4, 1957. It was developed by Soviet scientists led by Sergei Korolev. The satellite spent 92 days in orbit, making 1440 revolutions around the planet. This launch made it possible to study the upper layers of the ionosphere, as well as to obtain the most important information for further launches on the operating conditions of the equipment in space. Today, the number of operating artificial Earth satellites has approached 5 thousand. Trends tell how satellites have evolved over 65 years and what role they play today.
First satellites
“Sputnik-1” is the first satellite of the Earth in the history of mankind, it is also referred to as PS-1 (the simplest satellite No. 1). It was made in the form of an aluminum-magnesium alloy ball weighing 83,6 kg and 58 cm in diameter. The shell of the ball opened like two hemispheres, giving access to the interior of the satellite. It had no scientific equipment other than temperature and pressure sensors. It was also equipped with a radio transmitter with four antennas, which gave out short pulses at wavelengths of 20,005 and 40,002 MHz. Thanks to these radio transmissions, astronomers and radio engineers calculated the flight parameters of the satellite. Also inside the satellite was a power system weighing almost 50 kg. The device was designed in less than one year.
Just 32 days after the first launch, the USSR launched Sputnik 2 with a live passenger on board – the dog Laika. The device was a cone-shaped capsule 4 m high with a base diameter of 2 m. The capsule weighed about 500 kg. Engineering and biological data were transmitted from the satellite through the Tral telemetry system. The device communicated for a 15-minute period on each orbit. Two photometers were placed on board Sputnik-2 to measure solar radiation (ultraviolet and X-rays) and cosmic ray parameters. The readings of the device made it possible to detect the outer Van Allen radiation belt closer to the northern latitudes of the Earth.
First weather satellite
In 1960, NASA successfully launched the first successful meteorological satellite, Tiros-1. It transmitted infrared images of the Earth’s cloud cover and was capable of detecting and mapping hurricanes.
The body of the satellite was made in the form of an 18-sided prism, and the apparatus was powered by solar cells and a nickel-cadmium battery. Tiros-1 was equipped with two vidicons (TV cameras) – wide-angle and narrow-angle. Images from them were transmitted to a ground receiving station or stored on the onboard tape recorder when the satellite went beyond the range of the station. The device worked from April 1 to June 15, 1960, but is still in orbit.
First communications satellite
In 1962, NASA launched the first telecommunications satellite, Telstar-1. It enabled the first live transmission of television images between the United States and Europe. A 53-meter terrestrial antenna manufactured by AT&T Corporation was used to transmit the signal. The spherical satellite weighed 78 kg and was powered by 3600 solar cells. He worked with an active repeater that amplified the signal strength a hundred times.
Telstar-1 managed to operate for only seven months before it was disabled by high-altitude tests of US Starfish Prime nuclear warheads in space. Although the satellite is no longer operational, it remains in Earth orbit. The launch of the device allowed the formation of an international global satellite consortium (Intelsat), which manages a constellation of communication satellites that provide international broadcasting services.
Modern communications satellites include, for example, the Starlink constellation from SpaceX, which provides Internet access services in regions of the Earth with poor connectivity.
First satellite for geodata collection
In 1972, NASA launched Landsat-1, the first satellite to study the earth’s resources. It was built on a weather satellite platform. For monitoring, two instruments were installed on the device: the Return Beam Vidicon camera system, created by the American Radio Corporation, and a multispectral scanner from the Hughes Aircraft Company. The MSS instrument recorded data in four spectral bands—green, red, and two infrared bands. The device was equipped with a data acquisition subsystem (DCS) to collect information from remote ground stations and transmit them to central detection stations. The satellite had two broadband video recorders capable of storing up to 30 minutes of data from a scanner or camera. It weighed 953 kg and measured 1,5 x 3 m.
Landsat-1 worked until January 1978, which was five years more than the estimated service life. The satellite collected images of forests, urban areas and water sources on Earth. NASA launched the large-scale Landsat program to assess natural and anthropogenic changes on Earth, which has been operating for more than 40 years. The Landsat-9 satellite is currently in orbit. This latest version of the satellite uses optical and thermal sensors to capture images.
In 1974, NASA launched the first navigation satellite NTS-1 under the NavStar (NAVigation System with Time And Ranging) program. It was developed with the support of the US Department of Defense. The device weighed 293 kg and was powered by four deployable solar panels. It was equipped with quartz and rubidium signal generators. The satellite broadcast a microwave signal from space, and the receiver on Earth used it to calculate its position in space in three coordinates in real time. Later, the NavStar program was renamed GPS (Global Positioning System, Russian “Global Positioning System”).
In 1994, the first GPS constellation of 24 geostationary satellites was launched. Satellite data is used not only in the field of navigation and defense, but also in telecom, geodesy, cartography, and so on. By 2022, the US Air Force has developed a new generation of GPS satellite NTS-3, which can be reprogrammed directly in orbit for various needs, and thanks to a reinforced antenna array, its signal strength can be adjusted.
mini satellites
In 1999, Professor Jordi Puig-Suary of California Polytechnic State University and Bob Twiggs of Stanford University proposed the CubeSat reference design, a miniaturized satellite for space exploration. It consists of several cubic blocks measuring 10 cm × 10 cm × 10 cm and weighing no more than 1,33 kg each.
CubeSat was first used for NASA’s Ames science mission. In 2006, the Biological CubeSat group launched the GeneSat-1 satellite to carry out biological experiments in space. So, the cubesat carried biological samples to analyze the effect of weightlessness on the degradation of human muscles. The samples did not need to be returned to Earth, since the satellite, using sensors, collected information about their condition and transmitted it. In 2018, the mini-satellite was used for the first time in the Mars InSight interplanetary mission. Two MarCO CubeSats A and B served as communication relays for the lander as it reached the surface of Mars.
Cubesats are usually launched in batches either from launch vehicles or from cargo spacecraft and orbital stations. Most cubesats carry one or two scientific instruments with small retractable antennas and solar arrays. The launch of a cubesat can be requested, for example, by a university, while the mini-satellite can be made by the students themselves.
Additionally, the cubesat can be equipped with a selfie camera, solar sail, flash memory for remote data storage, signal receivers and other equipment. Thanks to 3D printing technologies, small satellites are becoming cheaper to manufacture, and they themselves can perform an ever wider range of tasks.
Nanosatellites
Scientist Zack Manchester of Stanford University in 2011 presented a model of a tiny femtosatellite KickSat. In fact, this is a cubesat that can hold a hundred sprites – computer boards with an antenna, each of which is capable of operating as a microsatellite. Manchester raised donations for such programmable boards on Kickstarter. It is assumed that such a device costing several hundred dollars is available to everyone. So far, KickSat has only been launched into space twice.
What will the satellites be like?
With “green” engines
Now satellites mainly use electric engines, but developers offer more environmentally friendly options – electromagnetic, nuclear, solar, water, laser and even iodine engines.
For example, Singapore-based startup Aliena makes the MUSIC Electric Propulsion System miniature eco-friendly propulsion systems for the mobility of small satellites in space. Plasma engines allow small satellite operators to reduce their fuel consumption.
Engineers of the French company ThrustMe are testing the engine on iodine. It is designed to replace xenon in the propulsion system, a rare gas in nature with a small thrust force. The company has already conducted a series of successful tests of the NPT30-I2 engine in low Earth orbit. As the developers noted, the design of the iodine-fueled engine is more compact and simple, since it does not need gas tanks, pressure control systems and other technologies.
High throughput
Demand for satellite mobile and broadband is growing, and service providers are developing solutions to increase the capacity of their satellites. Companies are implementing advanced repeaters to transfer data at speeds of several hundred gigabytes or even terabytes per second, as well as introducing improved antennas. This allows the satellites to operate in the Ku and Ka bands, which provide greater signal throughput. Starlink satellites are already capable of connecting users to the Internet both in hard-to-reach regions of land, and on water and even in the air.
And American startup Cesium Astro has developed the Vireo active phased array system for satellites with size, weight, payload and cost limitations. In an active phased array, each element has its own miniature transmitter and receiver. Using this solution in a satellite antenna gives control over the power consumption and performance of the satellite constellation.
With sails
Since 2015, NASA has been testing the technology of a fundamentally new source of satellite movement – a solar sail. As part of the Advanced Composite Solar Sail System program, the agency has developed a deployable sail design that can carry a satellite using solar energy. This will save rocket fuel, which is spent on launching satellites into orbit. The sail booms are made of carbon fiber composite materials. It could potentially launch space weather early warning satellites, near-Earth asteroid reconnaissance missions, or communications relays for manned exploration missions. The first launch of a cubesat with such a sail is scheduled for early 2023.
Made from durable materials
NASA intends to launch a satellite maintenance robot (OSAM-1) into Earth orbit in a few years to refuel the Landsat-7 remote sensing satellite. OSAM-1 will use a robotic arm to carefully cut through the insulation layer and unscrew one bolt to fuel the craft with hydrazine fuel, a more environmentally friendly form of rocket fuel. If the mission is successful, then in the future the robot will be able to maintain the operation of satellites in orbit without the need to involve astronauts for this purpose. At the same time, the device itself will be able to work longer than the originally planned period. OSAM-1 can be regularly sent into orbit and returned back to Earth.
From eco-materials
For more than half a century, satellites have mostly been made of aluminum, which, although durable, is not safe for the environment and is not the cheapest material. Now developers are experimenting with materials – for example, the Japanese logging company Sumitomo Forestry, together with the University of Kyoto, promises to launch a cubesat made of wood in 2024. The device will contain an electronic substrate, which will be covered with wood and solar panels on the outside. The authors of the idea note that the tree does not prevent the penetration of electromagnetic waves, and it will be possible to install an antenna on the satellite. At the same time, it will burn out when leaving orbit. The company will test different types of wood.