Growing a flight technique to land heavier automobiles on Mar…
The heaviest automobile to efficiently land on Mars is the Curiosity Rover at 1 metric ton, about 2,200 kilos. Sending extra bold robotic missions to the floor of Mars, and finally people, would require landed payload lots within the 5- to 20-ton vary. To try this, we have to work out the right way to land extra mass. That was the objective of a current examine.
Usually, when a automobile enters the Mars environment at hypersonic speeds of about Mach 30, it slows down rapidly, deploys a parachute to decelerate extra then makes use of rocket engines or air luggage to complete the touchdown.
“Unfortunately, parachute systems do not scale well with increasing vehicle mass. The new idea is to eliminate the parachute and use larger rocket engines for descent,” mentioned Zach Putnam, assistant professor within the Division of Aerospace Engineering on the College of Illinois at Urbana-Champaign.
In response to Putnam, when the lander has slowed to about Mach 3, the retropropulsion engines are ignited, fired in the other way to gradual the automobile down for a protected touchdown. The difficulty is, that burns quite a lot of propellant. Propellant provides to automobile mass, which might rapidly drive up automobile value and exceed the present launch functionality right here on Earth. And each kilogram of propellant is a kilogram that may’t be payload: people, science devices, cargo, and so forth.
“When a vehicle is flying hypersonically, before the rocket engines are fired, some lift is generated and we can use that lift for steering,” Putnam mentioned. “If we move the center of gravity so that it’s not uniformly packaged, but heavier on one side, it will fly at a different angle.”
Putnam defined that the circulate across the automobile is totally different on the highest and the underside which creates an imbalance, a strain differential. As a result of the raise is in a single path, it may be used to steer the automobile because it decelerates by the environment.
“We have a certain amount of control authority during entry, descent, and landing — that is, the ability to steer.” Putnam mentioned. “Hypersonically, the automobile can use raise to steer. As soon as the descent engines are ignited, the engines have a certain quantity of propellant. You’ll be able to hearth engines in such a manner that you simply land very precisely, you may neglect about accuracy and use all of it to land the most important spacecraft potential, or you’ll find a stability in between.
“The query is, if we all know we’ll mild the descent engines at, say, Mach 3, how ought to we steer the automobile aerodynamically within the hypersonic regime in order that we use the minimal quantity of propellant and maximize the mass of the payload that we will land?
“To maximize the amount of mass we can landing on the surface, the altitude at which you ignite your descent engines is important, but also the angle your velocity vector makes with the horizon — how steep you’re coming in,” Putnam mentioned.
The examine clarified the right way to make the perfect use of the raise vector, utilizing optimum management strategies to establish management methods that can be utilized hypersonically throughout totally different interplanetary supply situations, automobile properties, and landed altitudes to maximise landed mass.
“Turns out, it is propellant-optimal to enter the atmosphere with the lift vector pointed down so the vehicle is diving. Then at just the right moment based on time or velocity, switch to lift up, so the vehicle pulls out and flies along at low altitude,” Putnam mentioned. “This enables the vehicle to spend more time flying low where the atmospheric density is higher. This increases the drag, reducing the amount of energy that must be removed by the descent engines.”