The heaviest spacecraft, delivered to Mars, is the Rover “Curiosity“. Weight Autonomous science 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 planting. The purpose of the recent study team of scientists from the University of Illinois, press release published by EurekAlert!, was precisely this.
Usually, when the craft enters the Martian atmosphere at hypersonic speed for about 30 strokes, it needs fast to slow, opening the parachute and using rocket engines or air cushion to complete the landing.
“Unfortunately, the parachute system is designed for little more massive vehicles. Our idea is to abandon the parachute and use larger rocket engines for the descent,” says the associate Professor of the Department of aerospace technology, University of Illinois Zach Putnam.
According to Putnam, when the descent module slows down to a speed of Mach 3, should be included electric motors, which will create reverse thrust and slow the machine to a safe landing. The problem is that such a maneuver burns a lot of fuel. Fuel typically represents the largest part of the mass of the apparatus, increase the cost of the entire run. Each kilogram of the fuel is minus kilogram payload: scientific instruments, equipment, people and so on.
“When the spacecraft reaches hypersonic speed, before the launch of rocket engines, there is a small amount of lifting force that can be used to control the device, says Panten. – If we move the center of gravity so that it is shifted to one side, the machine will fly at a different angle”.
Bantam explains that flows around the apparatus in the front and the back are different from each other, creating 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 atmospheric entry, descent and landing we have some ability to control the camera. We can change its direction. At hypersonic velocities that can be managed due to the lift force that occurs with the launch of brake motors that burn a certain amount of fuel. Management of starting the engine allows for a very accurate fit. If you need to plant a very large device, about the accuracy forget, otherwise we’ll have to burn all the fuel. But you can find a balance between these two ways”.
“Suppose we want to reduce the speed of descent of up to 3 Mach. How exactly are we supposed aerodynamic control of hypersonic mode to minimize fuel use and maximize the possible mass of the payload? To maximize the size of the mass, which we can down to the surface, it is important to consider the height at which you will need to run the engines of the lander, and the angle between the velocity vector and the horizon,” adds Pantam.
The calculations showed how best to use the vector lifting force and to control the descent to a planet depending on the characteristics of the rocket and altitude, to maximize deflatable mass.
“It turned out that from the point of view of fuel consumption, the most optimal would be to log in to the atmosphere so that the vector of the lift force was directed downwards, as if the missile dives. And then at the right moment, depending on speed and time, it needs to turn up and fly at low altitude. The more time the device will hold in a more dense atmosphere, the stronger and longer it will act on it aerodynamic resistance and the less you will need fuel for planting,” says Panten.
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