The heaviest spacecraft deliveredto Mars, is the rover Curiosity. The weight of an autonomous scientific laboratory is about one ton. Sending more ambitious missions to the Red Planet, and in the future, people, will require the use of heavier spacecraft weighing from 5 to 20 tons. For this it is necessary to develop new methods of landing. The goal of a recent study by a team of scientists from the University of Illinois, whose press release was published by EurekAlert !, was precisely this.
Usually, when the machine enters the atmosphere of Mars onhypersonic speed about 30 Mach, he must quickly slow down, opening a parachute and using rocket engines or airbags to complete the landing.
"Unfortunately, parachute systems are fewdesigned for more massive vehicles. Our idea is to abandon the parachute and use larger rocket engines for descent, ”says Associate Professor of the Department of Aerospace Technologies, University of Illinois, Zack Putnam.
According to Putnam, when the landerit slows down to the speed of 3 moves; the electric motors must turn on, which will create reverse thrust and slow down the apparatus for a safe landing. The problem is that such a maneuver burns a lot of fuel. Fuel, as a rule, constituting the bulk of the mass of the device, increase the cost of the entire launch. Every kilogram of fuel is a minus kilogram of payload: scientific instruments, equipment, people, and so on.
"When the spacecraft reacheshypersonic speed, before launching rocket engines there is a small amount of lifting force that can be used to control the device, - says Pantam. “If we move the center of gravity so that it moves to one of the sides, the device will fly from a different angle.”
Pantam explains that flows around the apparatus infront and rear parts are different from each other, which creates an imbalance, the difference in pressure. Since the lifting force is directed in one direction, it can be used to guide the apparatus during descent through the atmosphere.
"During entry into the atmosphere, descent and landingWe have some ability to control the device. We can change its direction. At hypersonic speeds, this control can be carried out at the expense of the lift force that occurs with the start of brake engines that burn a certain amount of fuel. The engine start control allows for a very accurate fit. If you need to put a very large machine, then you should forget about accuracy, otherwise you will have to burn all the fuel. But you can find a balance between these two ways. ”
"Suppose we want to slow downdescent up to 3 Machs. How exactly should we aerodynamically control it in hypersonic mode in order to minimize fuel usage while maximizing the mass of the possible payload? To maximize the volume of mass that we can lower to the surface, it is important to take into account the height at which it will be necessary to start the engines of the descent vehicle, as well as the angle between the velocity vector and the horizon line, ”adds Pantham.
Calculations showed how bestuse the lift vector and control the descent to the planet depending on the characteristics of the rocket and the altitude to maximize the descent.
"It turned out that in terms of fuel consumptionthe most optimal will be to enter the atmosphere so that the vector of lift is directed downwards, as if the rocket is diving. And then at the right moment, depending on speed and time, it should turn up and fly at a low altitude. The more time the unit spends in a denser atmosphere, the stronger and longer the aerodynamic resistance will affect it and the less fuel will be needed for planting, ”says Pantham.
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