Breakthrough Starshot launched the world's smallest satellite into Earth orbit

How small can the machine be made in Earth orbit? In 1957, the Soviet Union launched the first artificial satellite weighing 83.6 kilograms and the size of a basketball. On June 23, 2017, the European space company Breakthrough Starshot tested Sprite satellites, which are 3.5 centimeters in diameter, weighing 4 grams and cost only $ 25. The creators of the satellite were able to place solar batteries, a microprocessor, sensors and communications equipment on a surface comparable to a postage stamp.

Sprite does not have the same capabilities as a full-size satellite or a kubsat - they only have basic sensors such as magnetometers and gyros. However, Zac Manchester, creator of the concept of tiny satellites, hopes to upgrade them and add more advanced sensors. For example, chemical detectors, with which you can explore a foreign environment. According to Manchester, because of the cheapness of satellites, they can be sent to dangerous places, where astronauts do not usually send, so that Sprite can collect some of the readings.

The creator of the tiny satellites also added that in the future it will be possible to combine several of these into a network of hundreds and thousands of satellites - they will work as a single swarm. On each of them it is possible to place sensors that collect and transmit information to Earth.
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Breakthrough Starshot sent six satellites into space on an Indian rocket, or rather, installed one more on the outer casing of two more satellites - the Latvian Venta and the Italian Max Valier. The remaining four Max Valier will carry in the cargo container for some time. According to the team’s plans, after entering space, the Sprite should separate from the surface of large satellites. To date, the satellites have reached Earth orbit (about 600 kilometers).

Ground stations in California and New York received signals from Sprite, which is a very significant achievement. A tiny solar panel on the satellite generates only 100 milliwatts of electricity in direct sunlight. This is not enough to support the antenna of the simplest wireless router, but under ideal conditions, it is enough to transmit data from near-earth orbit at a speed close to that of a fax machine. These 100 milliwatts are enough to control Sprite's embedded microprocessors, which surpass the full-size satellites of the 90s in terms of computing power.

The team cannot yet say whether signals from several satellites are being received at different times, or only from one. Controllers are trying to connect with Max Valier, who may not have been able to deploy his own radio antenna.

Breakthrough Starshot is the brainchild of Stephen Hawking and Russian billionaire Yuri Milner. The goal of the project is to bring humanity closer to the nearest Alpha Centauri star system, which is 4.37 light years away. Hawking and Milner offered to do this with the help of many tiny satellites, and in the framework of the first mission they were successfully launched into Earth orbit.

For the first time, Sprite went into orbit in 2011 aboard the Space Shuttle Endeavor, which performed its penultimate mission. Then the shuttle delivered three Manchester satellites to the International Space Station (ISS), where they were installed outside, and worked for three years as part of a material science experiment. Since the satellites were placed on the surface facing away from Earth, Spite signals did not reach the planet. However, after returning from space, the satellites did not fail and continued to work.

The next demonstration of the microsatellite operation occurred in 2014, when a KickSat satellite the size of a box for shoes assembled using crowdfunding sent a hundred Sprite to orbit. But these satellites could not be tested to the full due to KickSat’s short lifespan due to fears that they could create (or become) uncontrollable particles of space debris that could pose a serious threat to astronauts who were in the Soyuz rocket on the way to the ISS at this very time.

The air forces of different countries use powerful radars to catalog and track most types of space debris in order to warn cosmonauts and satellites in advance. But Sprites are so small that they are hard to find in this way.

US federal services officially prohibit Sprite swarms and other satellites of similar dimensions to climb more than 400 kilometers above the Earth. Below this threshold, the bodies decay relatively quickly and burn in the atmosphere for several weeks or months. Zach Manchester says this is an informal comfort zone for the foreseeable future. However, he and his colleagues are working on methods that allow Sprite to be more easily captured by radars.

Before Sprite gets to the stars, Manchester is confident that satellites are more likely to first be used as a three-dimensional antenna in deep space to monitor changes in space weather that could threaten earth networks and orbital spacecraft.