Today our lifestyle would hardly be possible without the help of satellites. Many of the activities we do on Earth today depend heavily on these objects that lie many kilometers above our heads: from forest fires, deforestation, and controlling sea surface temperatures, to new As far as allowing connections in mobile technologies, such as 5G. inaccessible areas.
The new generation of low-cost, small satellites being launched into low orbits (between 500 and 1,000 kilometers above Earth) by companies such as Elon Musk’s SpaceX and UK-based OneWeb illustrate this growing trend.
Less is more
These satellites can be the size of a shoebox or even smaller, and yet some of them have been able to track the entire landmass of the planet in unprecedented detail. Over the next decade, it is expected that an average of more than 2,500 mini-satellites will be launched per year.
To get them into orbit as cheaply as possible, small satellites are often carried on larger rockets as part of shared missions. The development of smaller rockets would allow faster and more personalized access to space, which could open the market to a greater number of specialized providers.
“Smaller satellites can travel in larger shuttles, but this creates problems, such as the longer time it takes to put them in orbit, because you have to reserve a spot in advance and wait for the shuttle to go to the exact spot where you want to place the satellites”, explains Xavier Llero, commercial director and co-founder of Pangea Aerospace in Barcelona, Spain. “The companies that own these satellites need access to space individually. Needed.”
The EU-funded RRTB project, led by Pangea, is trying to find more cost-effective ways to launch small rockets that carry satellites weighing up to 500 kilograms into space. It is expected to have an engine ready for use before 2025.
The key is to find ways to reuse these microshuttles while minimizing their impact on re-entering Earth’s atmosphere and allowing them to land safely. In addition, using the shuttle more than once will also allow us to be more respectful of the environment.
“Thanks to this reuse, the investment is lower, fewer means of production are used and the launch frequency can be increased,” explains Llero. As indicated by the RRTB project, which will end this month after three years of operation, there is currently no proven way to achieve these objectives in Europe.
First section
At the heart of the RRTB project is the first section or the first part of the rocket, located at its base, which has been reused. This is the segment responsible for generating most of the momentum immediately after launch, after which it breaks up and falls back to Earth, often over the ocean. The other sections of the rocket, with lighter weights, continue to propel through space until their payload is established in orbit.
This first segment is often damaged not only during its high-speed descent through Earth’s atmosphere, but also by seawater. The difficulties and costs of recovering it and returning it to the launch site could cause more problems than it solves. “When it gets into the water, it becomes extremely difficult to reuse it,” Llero says.
According to him, the solution is to find a way by which the first segment of the rocket safely re-enters Earth’s atmosphere and lands at a docking station near the launch site or on a floating base. Also, the shuttle’s design must allow a sufficiently large payload for the operation to be economically viable.
To find ways to reduce the damage of microshuttles during re-entry and landing in the Earth’s atmosphere, the RRTB team has conducted wind tunnel tests on a miniaturized microrocket model.
The main purpose of these microlaunchers, according to Llairó, is to prevent the engine from turning on for re-entry into the atmosphere. By reducing the weight of the fuel required, this would allow the Shuttle to carry a higher initial payload.
A new nozzle
The team experienced difficulties in their research when the rocket featured a conventional bell-shaped nozzle surrounding the engine, but found more promising results using a conical shape. it nozzle type aerospike This contributes to the even distribution of heat, so that the impact to which the rocket is subjected is reduced.
“This allows it to enter the atmosphere more smoothly,” Llero says. “This applies not only to smaller shuttles, but also to larger ones. This was an unexpected finding, as we were not looking for something like this in the beginning.”
though the engine aerospike They consume less fuel than conventional engines, explains Llero, whose benefits have so far been eclipsed by the complexities and costs of their engineering, which must include the difficulties of cooling them. However, technologies such as 3D printing used by Pangea are making them more viable.
“the technology aerospike It will change the way we go to space and how we return to Earth”, says Llero. “It is an essential factor for the reusability of the rocket.” In the meantime, he says, the team is working on the engine to use It is planning to use bio-based methane as a propellant.
Efforts are being made to make various parts of the rocket more reusable, for example by using aluminum-based materials for the fuel tanks.
“The goal is for most of the rockets to land safely and as many components as possible can be reused so that the operation is viable from an economic point of view,” explains Llero.
Launch preparation
While RRTB focuses on the reusability of rockets, UK-based aerospace company Orbex is preparing to launch its own lightweight and eco-friendly micro-launcher.
As part of the flagship project funded by the European Union, Orbex last May unveiled the prototype of its 19-metre-tall rocket, which will become Europe’s first fully orbital shuttle for small satellites. The rocket is also designed with the aim of reusing parts that are recovered and that do not burn up in the atmosphere. While Orbex hasn’t revealed anything about it yet, a company spokesperson said the method is “completely novel.”
Orbex expects the prime rocket to be launched for the first time this year, pending certain prerequisites, such as being granted a launch license. “We have already sold several seats to commercial satellite providers, but we have not yet announced our first launch date,” said Chris Larmour, CEO of Orbex. Larmour was also the coordinator of the PRIME project, which runs for three years until June 2022.
A greener rocket
The rocket will use clean biopropane-based fuel, a by-product of biodiesel, a type of fuel derived from sources such as used vegetable oil and cooking oil.
It would be combined with liquid oxygen, a “cryogenic propellant”; That is, a gas is cooled to sub-zero temperatures and condensed to become a highly flammable liquid. With these measures, the rocket would reduce carbon emissions by up to 96% compared to a shuttle of similar size powered by fossil fuels. “Orbex’s prime rocket, powered by renewable biofuels, will be the most environmentally friendly rocket ever built,” says Larmour.
The fuel tanks are made of carbon fiber, which allows combining great resistance with low weight.
Orbex estimates that the Prime rocket weighs 30% less than conventional launchers, which contributes to greater efficiency and higher throughput, two important aspects for small satellites. Furthermore, the rocket has been designed in such a way that it does not leave any residue on Earth or in orbit. The company plans to launch 12 rockets a year from its Sutherland Space Center on the north coast of Scotland. The space center is also expected to be carbon neutral in both its construction and its operation.
Its relative proximity to Glasgow will help it take advantage of the area’s thriving space industry, with more satellites being built here than anywhere else in Europe. Orbex believes that this will provide the right context for players in the field to launch their satellites into space.
“The satellite industry and the need for shuttles to place satellites in specific orbits has grown in recent years and will continue to do so rapidly,” noted Larmore. “This creates a very high demand for sustainable and specialized launches for minisatellites.”
