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CubeSats are tiny and economical satellites that have opened up space for private companies and students. Trends understand how they work, what they are used for and what risks they carry
Where did CubeSat come from and how much does it cost to launch them
Professor Bob Twiggs of Stanford University once placed a box of Beanie Baby plush toys in front of his students and said, “Your job is to make a satellite that fits in here.” Back in 1999, no one could have thought that the project would not only go beyond academic work, but would give rise to an entire industry of nanosatellites called CubeSat. According to Nanosats, by August 2022, almost 2000 of these “cubes” had been launched into orbit around our planet.
A nanosatellite is one of the variants of small artificial satellites of the Earth. Since the launch cost primarily depends on weight, they are classified according to it. The limit for small ones is 1 ton, and the whole category looks like this:
- mini satellites – from 100 to 500 kg,
- microsatellites – from 10 to 100 kg,
- nanosatellites – from 1 to 10 kg,
- pico satellites – from 100 g to 1 kg,
- femtosatellites – less than 100 g.
The success of CubeSat was ensured by unification and standardization. Their dimensions and weight are strictly limited: 10x10x11,35 cm with a limit of 1,33 kg. These are the limits for one “cube”, which is denoted as 1U or one unit, that is, one unit. They can be combined into groups of 2, 3, 6, 12 and 24 pieces: then you get an array of 2U, 3U, and so on. And in 2009, the PocketQube format appeared. This is a reduced size of 1/8 (5x5x5 cm and 250 g) of the classic CubeSat, but there are still few of them in orbit – only a few dozen.
Creating a CubeSat from scratch is time-consuming and expensive, but in most cases it is not required. Typically, nanosatellites are assembled from off-the-shelf “spare parts” that are purchased individually or as a kit for assembly. Their cost varies from several thousand to several tens of thousands of dollars, and the price of components of a finished 1U CubeSat usually does not exceed $100. It remains to add another $000 per kilogram of launch weight, and you can start your own space program.
Of course, for personal projects it is a little expensive, but the amounts are absolutely lifting for universities, research laboratories and commercial companies. In some countries, CubeSats have become the first national satellites. For example, in 2018, Bhutan sent its own “cube” on a SpaceX Falcon 9 rocket into space. The objective of the project was to demonstrate the capabilities of the platform, collect data from ground sensors and satellite imagery. The creation of the satellite, the launch and training of specialists cost the government only $280.
For comparison, just launching a mini-satellite, whose weight does not exceed 200 kg, costs around $1 million, and its development and creation, unlike CubeSat, which takes 6-9 months, can take years. As a result, by the time they are sent into space, large vehicles with obsolete equipment are often launched.
What is inside the CubeSat and what is it for?
For creating housing CubeSat use four kinds of aluminum alloy. This is necessary so that both the satellites and the launch vehicle that puts them into orbit have the same coefficient of thermal expansion. That is, so that they equally increase in volume as they are heated at constant pressure. At the same time, a special coating is also added, which excludes the situation of cold welding, when, under vacuum conditions, electrons from one piece of metal with a clean surface pass into another, forming a common crystal lattice.
Inside the “cube” are necessarily several microcomputers, which perform calculations and control the work of the entire other electronics. The tasks of the satellite can be very different, but there are four types of the most common missions.
- Test something in the conditions closest to reality before being used in more complex and expensive space projects. For example, running equipment for shooting or learning new materials.
- Scientific research. One option is to collect information about the planet’s magnetic field and its fluctuations for the early detection of earthquakes. Experiments can even be biological. This year, NASA plans to send a CubeSat with yeast strains to the moon to study the effects of radiation on living organisms as part of the BioSentinel project.
- Educational projects. For CubeSat students, this is a unique opportunity to follow the entire cycle of creating an unmanned spacecraft and take part in its development while still at an educational institution. The application here is also mainly scientific: photography, the study of the atmosphere, climate, movement of animal populations, etc.
- Commercial projects. The information that the CubeSat put into orbit allows you to receive can be sold. For example, photographs of fields from space will be of interest to farmers, and images of cities will be of interest to those responsible for their development. It is photography (and also recording short videos) that SkySat satellites from Planet Labs, made in the CubeSat form factor, are engaged in. There are 21 such vehicles orbiting the Earth right now.
Of course, in order to transmit data to Earth and receive commands, the “cube” needs antenna. The main limitation is usually the available power: it should not exceed 2 watts. Communication operates in the VHF, UHF, F, S, C and X bands, and the antenna is usually deployed after entering orbit. It can range from a simple wire solution to a complex inflatable parabolic system.
Power supply system in CubeSat most often combined. On the one hand, these are batteries, the dimensions and weight of which are especially difficult to minimize. On the other hand, the means of recharging them, which are most often solar panels. In most cases, they are rigidly fixed on the faces of the “cube”, but they can also be unfolding, which complicates and increases the cost of the design.
And finally, CubeSat must somehow change position in spaceso that, for example, the lens of a camera mounted on it is directed to the desired point. Devices like jet wheels help with this. And for directional movements propulsion systems are responsible: they can be based on the release of an inert gas and chemical reactions. Electric solutions are also available, but they require larger batteries and larger solar panels. There is also an option that does not require energy at all – folding solar sails. However, they must be large, and they still need to be decomposed after entering orbit – fault tolerance is reduced.
Pitfalls of CubeSat: space junk and data protection
There are two ways to send the CubeSat into space. First, as a secondary payload. Often referred to as a rideshare, the launch vehicle operator sells nanosatellite owners small space for satellites of a few kilograms, which can also be shared with others. Just such an approach can significantly reduce the cost of launch. After reaching the desired height, the satellites “shoot back” from a special P-POD device or more advanced analogues. In the process of entering orbit, its durable case protects them from damage. The second way to launch the “cubes” is to bring them in the form of regular cargo to the ISS, and then send them into space using a launch device like NRCSD.
According to Nanosats, a sharp increase in the number of nanosatellite launches per year occurred in 2012: it began to number in the tens. Since 2017, the count has already reached hundreds, and the final value for 2021 is 326 launches into orbit. True, not only full-sized CubeSats from 1U and more are taken into account here, but also compact versions of 0,25U. Forecast of site analysts for 2023–2026: 300–400 launches per year.
There are quite a lot of nanosatellites, so they are often referred to as “space debris”, emphasizing that student projects are not worth the risk of losing serious devices and increasing the likelihood of Kessler’s syndrome. This is a theoretical situation when there are so many useful objects and debris in the orbit of the planet that at some point there are critically many collisions. Everything begins to shatter into small and large fragments exponentially, which makes near space unusable.
According to the European Space Agency, there are now more than 130 million objects up to a centimeter in size, more than 1 million objects ranging in size from 1 to 10 cm and 36,5 thousand objects larger than 10 cm in Earth orbit. fragments fly at an impressive speed: about 28 km / h.
However, specifically with CubeSat, everything is not so scary: they are very far away from the geostationary orbit of 36 km, where the satellite cannot be physically disposed of. Only a few “cubes” rise above 000-700 km, and in most cases they operate at an altitude of 800 to 400 km, and this is one of the least “populated” orbits. Here, CubeSats operate from 600 to 1 years, gradually descending to the lower layers of the atmosphere, where they burn out during deceleration.
The real problems arise when the “cubes”, especially in large constellations, are sent to orbits above 700 kilometers. This question really worries experts. So far, the main proposal is the introduction of engines that take the device at the end of its service life to the lower layers of the atmosphere for destruction. By the way, a solution suitable just for such cases was recently presented by engineers from the Moscow Aviation Institute. The test in space is scheduled for 2023.
Another significant issue of CubeSat is related to security. It’s too early to worry that anyone from space might be collecting someone’s private data on Earth. But with protection against hacking, the satellites themselves are far from being as good as we would like. The introduction of cybersecurity practices, which have long become the gold standard of the industry on Earth, in amateur and semi-professional space projects is just beginning. Although there is no official confirmation of satellite hacking, the theoretical possibility of such a scenario has long been proven by experiments. For example, in April of this year, with the permission of the US Air Force, a group of enthusiasts hacked into a decommissioned broadcast satellite launched in 2005.
CubeSat in the world and in our country
The vast majority of nanosatellites ever sent into space belong to the United States: in Nanosats statistics for August 2022, this is 1869 devices with a share of 53,9%. Another 25,6% are European countries with 888 devices. China (2,9% and 100 satellites), Japan (2,8%, 96), Canada (2,1%, 72) and our country (2%, 71) follow. At the same time, our country plays a significant role in the process of launching “cubes”: they are often sent into orbit as a secondary load of Russian Soyuz-2 launch vehicles. It was on one of its modifications that 16 domestic CubeSats were launched in August this year, together with the Iranian Khayyam satellite.
The most notable developer of nanosatellites based on the CubeSat standard in our country is Sputniks, founded in 2011. She already has 20 “cubes” sent into space, half of which took off just on the Soyuz-2 mentioned above in August. The company’s product range includes both CubeSat constructors based on its own Orbicraft-Pro platform, as well as individual components.
To launch educational nanosatellites in our country, the Universat program is operating, in which several large universities of the country with strong technical faculties participate. By the fall of 2020, 7 CubeSat satellites were launched into orbit using it, which were developed at Moscow State University, AmSU, NSU and Moscow State Technical University. Bauman. In 2021 and 2022, HSE also received two of its own “cubes”. It is likely that over time, the first Russian private space company SR Space, whose founder plans to introduce his own payload-capable rocket in 2024, will also become a new driver of the industry.
It is quite difficult to launch even a small spacecraft, not only because of the peculiarities of development and budgeting. The fact is that there is no such thing as a “private satellite” in the world – they always belong to some country. And Article II of the “Convention on International Liability for Damage Caused by Space Objects” says that “the launching state bears absolute responsibility for paying compensation for damage caused by its space object.” The most famous precedent is the fall of parts of the Soviet 4300-kilogram military satellite Kosmos-954 into the territory of three provinces of Canada in 1978. Fortunately, the nuclear reactor installed on it burned down in the atmosphere and there were no casualties. After long negotiations, the leadership of the USSR agreed to pay half of the invoice for 6 million Canadian dollars.
our country also participates in this agreement, therefore, to launch even a 1U “cube”, it is necessary to obtain government permission. Such complex formalities are usually taken over by the launch operator, which in the Russian Federation is Glavkosmos. After the start of work, the orbital characteristics of your apparatus must be transferred to Roscosmos for inclusion in the catalog. To work with communications, permission from the relevant structures will also be required, depending on the chosen method and frequency of broadcasting.