CuriosityThe Robotic Rover on Mars

Aviel AtiasOmri Ben EliezerYaniv Sabo

29/04/13

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Exploring Mars Goals of Mars Exploring

•Signs of Life?•Water

•Inspecting chemical elements

•Inhabitation of Mars?•Weather and radiation

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Exploring Mars History of Mars Exploration

•Since 1960•50 attempts, 21 of them succeeded

•Two older rovers are still on their mission

Types of Spacecrafts•Orbiter

•Lander•Rover

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•A car-sized robotic rover exploring Gale Crater( )מכתשon Mars right now as part of NASA’s Mars science laboratory mission.

Curiosity

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The Curiosity Project

•2.5 billion dollars

Cost

•A total of 56,000 years of work

How many people worked on it?

•8 years of planning, building and testing

Time

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Structure of Curiosity

•One brain to control them all•Radioisotope thermoelectric power generator

•Converts heat from the natural decay of Plutonium into electricity

•Is a reliable source of energy for 20+ years •Special mobility system, motors and gears•Designed to work on the rocky surface of

Mars

Electrical Drive System

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Structure of Curiosity

•Communicates with earth via orbiters of Mars•Can also communicate directly with earth

Communication System

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•A special computer that can handle extreme situations:

•varying temperatures (-127⁰ to 40⁰ C)•High Radiation

Curiosity’s Brain

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•Radiation Hardened Memory•256 KB of EEPROM

•256 MB of DRAM•2 GB of Flash Memory

•RAD750 Board•200 MHz CPU

•400 MIPS (million instructions per second)•VxWorks Operating System

•27 years old•Specialized for space-missions

•Costs $200,000 and up

Specifications

Curiosity’s Brain

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Curiosity’s Brain

•Radiation Hardened Memory•256 MB of DRAM

•2GB DRAM•2 GB of Flash Memory

•64 GB•RAD750 Board•200 MHz CPU

•Quad-Core, 1.9 GHz•400 MIPS (million instructions per second)

•10K MIPS•Costs $200,000 and up•Costs a few hundred $

In Comparison With a Modern Smartphone…

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Curiosity’s Brain

•In February 2013, a problem in the flash memory caused the computer to continuously reboot in a loop

•How do we handle system failures in a robot so far away?

•It may make the whole mission fail•In first place, the systems must be very stable

•Each system has a few backup systems

A Bug!

Robotic Arm

• The rover has a 2.1 m long arm with holding five devices that can spin through a 350-degree

• The arm makes use of three joints to extend it forward and to stow it again while driving

• It has a mass of 30 kg and its diameter is about 60 cm• Two of the five devices are contact instruments known as the X-ray

spectrometer (APXS), and the Mars Hand Lens Imager (MAHLI camera)• The remaining three are associated with sample acquisition and sample

preparation functions: a percussion drill, a brush, and mechanisms for scooping, sieving and portioning samples of powdered rock and soil

• The diameter of the hole in a rock after drilling is 1.6 cm and up to 5 cm deep

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Robotic Arm – cont.• 5 degrees of freedom.• Capable of surviving temperature range of [-

1280C, +500C]. Operating in [-1100C, +500C].

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MAHLI camera

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Navigation Cameras (Navcams)• The rover has two pairs of

black and white navigation cameras mounted on the mast to support ground navigation

• The cameras have a 45 degree angle of view and use visible light to capture stereoscopic 3-D imagery.

• These cameras support use of the ICER image compression format.

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Hazard Avoidance Cameras• The rover has four pairs of black and white navigation cameras

called Hazcams—two pairs in the front and two pairs in the back• They are used for autonomous hazard avoidance during rover

drives and for safe positioning of the robotic arm on rocks and soils

• The cameras use visible light to capture stereoscopic three-dimensional (3-D) imagery

• The cameras have a 120 degree field of view and map the terrain at up to 3 m in front of the rover

• This imagery safeguards against the rover crashing into unexpected obstacles, and works in tandem with software that allows the rover to make its own safety choices

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Hazard Avoidance Cameras - cont.

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How to land a robot on mars?

• The atmosphere is too thin for parachutes and aerobraking alone to be effective.

• Some previous missions have used airbags to cushion the shock of landing,but Curiosity rover is too heavy for this.

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The EDL (entry-descent-landing) system

• During the entire landing phase, the vehicle acts autonomously.

• This system is more than 20 times accurate, compared to older landing systems.

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EDL phase 1: Guided entry• The rover was folded up

within an heat shield that protected it during the atmospheric entry.

• The heat shield diameter is 4.5 m, which is the largest heat shield ever flown in space.

• The heat shield experienced peak temperatures of up to 2,090 °C.

• It reduced the velocity of the spacecraft from approximately 5.8 km/s down to approximately 470 m/s, where parachute is possible.

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EDL phase 2: Parachute descent• When the entry phase was complete and the capsule was at

about 10 km altitude, the supersonic parachute deployed.• The parachute has 80

suspension lines, is over50 m long, and is about16 m in diameter.

• The parachute is capableof being deployed at Mach2.2, and can generate up to289 kN of drag force in the atmosphere.

• After the parachute was deployed, the heat shield separated and fell away.

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Parachute descent (contd.)

• The Mars Reconnaissance Orbiter team were able to acquire this image:

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EDL phase 3: Powered descent

• At about 1.8 km altitude, stilltravelling at about 100 m/s,the rover and descent stagedropped out of the aeroshell.

• The descent stage is a platform above the rover with eight hydrazine rockets on arms extending around this platform to slow the descent.

• Each rocket produces 400 N to 3,100 N of thrust.

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EDL phase 4: Sky crane landing• The sky crane system lowered the rover on three nylon

tethers and an electrical cable carrying information and power between.

• At 7.5 m below the descent stage the sky crane system slowed to a halt and the rover touched down. After the rover touched down, it waited 2 seconds to confirm that it was on solid ground by detecting the weight on the wheels and fired several pyros activating cable cutters.

• The descent stage flew away to a crash landing 650 m.

• The sky crane powered descent landing system had never been used in missions before.

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Sky crane landing (contd.)

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Thriller

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