An economical way to deliver multi-ton cargo to Mars
The heaviest spacecraft delivered to Mars, a rover "Kyuriositi". Weight autonomous science lab 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 5 to 20 tons. This requires the development of new planting techniques. The purpose of a recent study team of scientists from the University of Illinois, is a press release issued EurekAlert !, was just in it.
Normally, when the unit enters the Martian atmosphere at hypersonic speed of Mach 30, it must be slowed down quickly, opening a parachute and involving rocket engines or air cushions to complete the landing.
"Unfortunately, little parachute systems are designed for the more massive vehicles. Our idea is to give up the parachute and use of larger rocket engines for descent ", - says assistant professor 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 involved electric motors that create reverse thrust and slow down the device for a safe landing. The problem is that such a maneuver burns a lot of fuel. Fuel, as a rule, constitute the bulk of the mass of the device, increase the cost of the entire run. Each kilogram of fuel - is a minus kilogram payload: scientific instruments, equipment, people, and so on.
"When the spacecraft reaches hypersonic speed before launching rocket engines arises a small amount of lift that can be used to control the apparatus, - says Pantem. - If we shift the center of gravity so that it is shifted to one side, the unit will fly from a different angle. "
Pantem explains that flows around the unit in front 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 its descent through the atmosphere.
"During reentry, descent and landing, we have a possibility of some device management. We can change its direction. At hypersonic velocities it can be controlled due to the lifting force, which arises from running brake motors, a certain amount of fuel burning. engine starting control allows for a very precise fit. If you want to put a very large unit, then the accuracy is necessary to forget, otherwise it is necessary to burn all the fuel. But you can find a balance between these two methods. "
"Let's assume that we want to reduce the shutter speed up to Mach 3. As it is we have to manage it in an aerodynamically hypersonic mode to minimize fuel use and thus maximize the possible weight of payload? To maximize the amount of mass that we will be able to pull on the surface, it is important to take into account the height at which it will be necessary to run the engines lander, and the angle between the velocity vector and the horizon "- adds Pantem.
The calculations show how to best use the lift vector and control the descent to the planet, depending on the characteristics of the missile and the altitude to maximize the lowered mass.
"It turned out that in terms of fuel consumption the most optimal would be to log into the atmosphere so that the vector of lift was sent down like a rocket dives. And then at the right time, which depends on the speed and the time it needs to turn up and fly at a low altitude. The more time the unit will spend in a more dense atmosphere, the harder and longer it will act upon it the aerodynamic drag and the less fuel is required for landing ", - says Pantem.
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