The NASA developed tires with a memory effect for the new Mars rover
During his five-year stay on the Red Planet rover "Kyuriositi" has done tremendous research work and made a lot of interesting scientific discoveries. And in all that time an autonomous Mars Science Laboratory, of course, had a lot to ride on the surface of our planetary neighbor. Nevertheless, in 2013, during a routine check of the control command "Kyuriositi" was very surprised by the fact that all six of the rover's wheels have different damage, including such as in the image below.
Realizing that the future rover, which is going to send to Mars by the mid 2020s, can expect similar problems, a team of engineers from the Glenn Research Center (NASA) has decided to develop a new type of wheel.
Start, perhaps, is with the fact that the construction of new wheels based on an earlier prototype Spring Tire - airless tire developed by Goodyear in collaboration with NASA in the mid-2000s. What is interesting, the original version of airless tires first appeared even earlier - in the bearded 70th and then again as a result of cooperation Goodyear and NASA. However, new tires, instead of using a spring-wire structures used in the original model, a team from NASA decided to use a more robust and flexible design.
Moon, Mars and other planets in our solar system have a very unfriendly, harsh landscape. In the case of the moon creates a fundamental problem regolith that covers almost the entire surface of the satellite. This fine dust is a residual soil, which space weathered rocks and the product is capable of easily damage the mechanical parts of the vehicle. On Mars, the situation is hardly easier: there is a large part of the surface is covered with regolith not only, but also a small sharp stones that even iron can be cut with ease. In 2013, after only one year of activity on the surface of Mars, the wheel "Kyuriositi" began to show signs of serious wear and tear. This situation has forced worried scientists who began to doubt that the rover will be able to complete its planned mission. As a result of this and also led to the fact that Glenn Research Center decided to review the design of the tire, the development of which at that time was conducted almost a decade. Tires are designed with the prospect of a return to the lunar program.
Development of new space for the tire Glenn Research Center in general was one of the priorities of the last ten years. In this regard, NASA engineers and scientists returned several times to the developments that have remained ever since the era of space missions "Apollo". At that time, in the development of the American and Soviet space program several different tires have been developed, intended for use on the lunar surface. Center chose Glenn as a basis three options.
The first was used in the Soviet "Lunokhod". In its eight-based metal used tires, united with the axis through a plurality of spokes. On the outer side of the tire had a metal tread designed to provide a tighter grip with lunar soil.
In consideration also hit tire applied in special wheelbarrow Modularized Equipment Transporter (MET), which was used to transport astronauts lunar soil samples in one mission "Apollo". Tire development for her, too, was carried out jointly with the Goodyear company. She has been non-motorized wheelbarrow, and the astronauts had to put a lot of physical effort for its transportation. Nevertheless, its tires had a smooth rubberized surface, which simplifies its movement along the ground and rocks. The third design of tires for which it was decided to apply, used the so-called Moon car that was used by astronauts in the mission "Apollo 15," "Apollo 16" and "Apollo 17". It piloted the vehicle to use four large wheels with solid inner frame and protector in the form of a flexible wire grid structure. In the mid-2000s, when NASA beginning to prepare for a possible new lunar missions (with the prospect of future missions to Mars), the engineers decided to revise the design of the car tires Moon to include new technologies and use of new and more durable materials. As a result, the light appeared the very same tire Spring Tire. Tread airless tire consisted of a plurality of interconnected metal rings (as in mail), making it both durable and flexible. Such a design does not only allow to reduce weight, but showed a high capacity even in severe movement on the surface.
To test the behavior of the tire Spring Tire on the surface of Mars, engineers from the Glenn Research Center began conducting tests on a special testing ground, designed to simulate the surface conditions. Despite the fact that in general the tires proved themselves worthy during movement of modeled Martian soil, they have a serious problem - the sharp stones on which moved the test pattern began to deform the tire is not only, but also literally rip them.
As a result, engineers again went to work. The solution was to use superelastic tires, which have become an extension of "spring" tire Spring Tire. In new tires used special TiNi alloy, also known as Nitinol. This material is a leader among alloys with shape memory effect. It is able to recover fully after a 10 percent strain. In the same tires Spring Tire, the figure is only 0, 3-0, 5 percent.
In addition, tire advantage of nitinol is light weight (in the same experimental prototype it is only nine kilograms), can adjust the level of adhesion to any surface and high damping properties. Tires with a memory effect is also increased and the index of flexibility, which in general has a positive impact on their longevity.
"Firstly, these tires allow to conduct research on a variety of types of surfaces. Secondly, because they are lighter and generally able to adapt to a particular type of surface, they can not dig into the ground, the more rigid and heavy wheels, and are able to cope with heavier loads. In addition, since the tire shape memory capable of absorbing energy from the impact of the ground at different speeds, they can be used to drive a vehicle whose speed is expected to be substantially higher than the current rovers, "- stated on the website of Glenn Research Center.
The use of superelastic tires need not be limited to the space program. Already among the potential areas considered tires for passenger cars and off-road, military, agricultural and aviation equipment. Developers have already established an experimental tire on the Jeep Wrangler SUV and experienced her work in the real world.
As the first real use of such tires, it will stand out this possibility in the next few years, when NASA sends to the surface of the Red Planet's new rover. If all goes according to plan, it will take place sometime in 2020. The new rover will be designed to replace the "Kyuriositi" in his mission to search for signs of life on Mars. In addition, the front of the rover will be tasked to collect samples of Martian soil, which is scheduled to return to Earth as part of a manned mission, which is to be held somewhere in the 2030's.