Ch5 - Mars Rover
People have always gazed upon the cosmos hoping that one day they will be able to walk on planets other than Earth. They were right. In the mid '70s, a soviet cosmic plan, the Luna Programme, was launched and first rovers were sent to the Moon. Their mission was to take pictures and carry out tests on its rocky surface. The objective behind this was to test the conditions, so that mankind could prepare to send the first man to the Moon.
The first Moon landing of the Apollo 11 with Neil Armstrong and crew aboard happened on 20th July 1969 as part of the Apollo program. After that enormous step, other spaceships and probes were sent to the Moon, in order to examine its surface.
Now, the mankind faces a bigger challenge – exploration of Mars. Just like when it came to exploring the Moon, people first send probes and rovers to examine this planet and prepare for sending the first man to Mars.
The first rover to land on Mars was a soviet PrOP-M, which arrived there in December 1971. Unfortunately, it failed to gather any data, because just a few seconds after the landing it lost contact with Earth. The first successful mission was landing of the rover Sojourner on July 4th, 1997. It was a small rover – weighing merely 10,5 kg – and just like the previous one, it was powered with solar panels. It managed to send over 500 photos and analyse the chemical makeup of Martian rocks.
The latest accomplishment in Mars exploration is sending two twin rovers, Spirit and Opportunity in 2004, as a part of Mars Exploration Rover program. They were much heavier than any of the previous rovers and they weighed 185 kg each. Both rovers stayed on Mars longer than the program predicted, but Opportunity operated until the 7th August 2012. The rovers have finally established that at some point in the past, there was water on Mars.
On the 26th November 2011, NASA sent the Curiosity rover to Mars, as part of the Mars Science Laboratory program. The rover is equipped with the most recent technologies and has a lot of interesting solutions. Its mobile base was thoroughly measured and allows the rover to move on uneven terrain. The rover has as many as 15 cameras: 7 on its mast and 8 under its trunk. They create a precise, spatial picture of Mars’ surface. Curiosity is also equipped with an environmental monitoring station that analyzes changes in the planet atmosphere.
The robot has a robotic arm. The arm is equipped with a hammer drill to collect samples from inside of the rocks, a wired brush to dust the rocks, a device for analysing the chemical makeup of the rocks, and a device for collecting and preparing test samples.
The mission to deliver Curiosity on Mars was very complicated. It begun on the 26th November 2011 with a cruise phase that lasted 210 days. During this time, many system controls and correction manoeuvres were performed to ensure that the rover followed the right track. In this phase, special equipment was used to warm up the temperature-sensitive systems.
The last phase involved entering the atmosphere and landing. It was the shortest phase, as it lasted no more than 10 seconds, yet it was vital for the mission. Ten minutes before entering the atmosphere, the rover disconnected from the flight module and entered the atmosphere about 130 km above the surface of Mars. Then, the engines activated and enabled the rover to safely enter the atmosphere.
The next phase involved deploying a parachute. This happened on the altitude of 11 km, when the ship was falling with the speed of 400m/s. Then, the lower part of the capsule (the lander) detached from the atmospheric module with the parachute. The landing engines activated and reduced the falling speed. During the descent, the Sky Crane system was initiated. When the rover touched the Martian surface, the capsule with the crane detached and flew a safe distance away. After the landing, the board computer switched to the surface mode and the rover sent its first pictures of Mars to Earth via the Mars Odyssey satellite.
Build
To build this construction, you will need LEGO Education WeDo
Explore
This is the comlpete mars rover model.
The construction includes electronic elements, such as distance sensor, hub, or motor, and interesting gear transmissions.
The transmission propelling the fornt wheels was inspired by the differential gear train, used in cars and other wheeled vehicles.
1. The hub allows to connect the model with the computer, powers the motor and receives information from the sensor.
2. The motion sensor is used in the control program.
3. The vehicle moves thanks to the motor, which propels gears inside the transmission and transfers the drive to the wheels.
The mars rover model has two different wheel types.
1. The four tires installed on the rear axles are smaller than the ones in the front.
Note that the entire model rests on the two rearmost tires. The middle axle is slightly higher, which makes it easier for the vehicle to turn.
2. The front wheels are propelled by the motor.
The rover had a module for research purposes: the probe.
1. You can turn the arm with probe by using the lever.
The entire arm rotates because of the bevel gear inside.
Rovers that explore planets other than Earth are powered by solar energy.
This model has two solar panels that you can set at an appropriate angle.
1. It's possible because of the ball joints.
2. On top of the panels, you can see gear racks, which imitate photovoltaic materials used in real-life solar batteries.
This model can move forward in a straight line, or, if there's an obstacle on its way, it can turn.
1. This axle is propelled by the motor.
2. That axle can transfer drive to the next transmission that propels the wheels, but it can also make the front axle turn. This transmission was inspired by the differential gear train.
This is how the mechanism inside looks like when working.
1. This cogwheel will always rotate.
2. If this axle gets blocked, for example if there's an obstacle in front of the vehicle, the first gear will make the entire axle turn, which will allow the rover to continue exploring.
Program
The program for the rover will allow it to move forwards, backwards and to stop the vehicle in front of a sample.
