Mars Exploration

rover equipment deck

TWO GENERATIONS OF ROVER

MER meets Sojourner in the lob at JPL. The larger rover borrowed the rocker-bogie suspension system developed for Sojourner - each wheel has independent suspension and keeps contact with the ground at all times, reducing the risk of sudden bumps and shocks. The MER has rolled over large rocks and rough terrain with few problems.

height weight number of instruments power source manufacturer launch dates stereoscopic navcams allow rover to build up 3-D model of its surroundings

Rover

NASA's second generation of Mars rovers built on the success of 1997's Mars Pathfinder mission. But the two Mars Exploration Rovers (MERs) were to be much larger and more robust vehicles, capable of direct communication with Earth or the various Martian orbiters without using a base-station relay. A unique suspension and drive system, powered by a large array of solar panels on the MER's upper surface, allowed it to negotiate almost any hazard on the Martian surface with ease. Cameras and other scientific instruments were mounted on a raised mast and on a small robot arm - the Instrument Deployment Device (IDD).

185kg (407lb)

7 including PanCam

Top-mounted solar arrays

JPL/Caltech

10 June 2003 (Spirit), 8 July 2003 (Opportunity)

Instrument

Deployment

Device

IDD instruments and tools - spectrometers, camera, and a Rock

Abrasion Tool (RAT)

SLOW BUT SURE

The MER is a high-performance vehicle: independent motors on each wheel allow it to negotiate most obstacles, and it can turn on the tightest of angles. However, it is not the fastest vehicle - its top speed on Mars is about 5cm (2in) per second, and it stops every few seconds to allow its computer to study the route ahead.

PanCam

(panoramic camera)

TWINS

The MER rovers were built side-by-side at the Jet Propulsion Laboratory. Developing a pair of probes is always a good policy as it is a cost-effective way of doubling the science yield from a project and also helps insure against failures.

length copture/filter magnets for finding iron in dust rocker-bogie mobility system

PanCam mast assembly

Pancam Mast Mer

HAPPY LANDINGS

low-gain antenna

Low Gain Antenna

PanCam calibration target high-gain antenna solar arrays for power generation aluminium wheels wheel cleat for traction and soil excavation low-gain antenna

PanCam calibration target

READY FOR LAUNCH

The launch tower at Cape Canaveral's Pad 17-A rolls back to reveal the Delta II rocket that would launch Spirit on its way to Mars. For the seven-month journey, the aeroshell was mounted on a disc-shaped cruise stage carrying communications equipment, guidance systems, and thrusters for course adjustments en route.

PACKING UP THE ROVERS

The completed MER package fitted neatly inside an aeroshell, a two-part aerodynamic capsule designed to protect the lander through re-entry and then break apart and fall away.

high-gain antenna solar arrays for power generation aluminium wheels wheel cleat for traction and soil excavation

HAPPY LANDINGS

ENCLOSURE

With its solar arrays folded inwards for protection, each MER was then enclosed in a simple lander, consisting of four triangular panels that folded and joined to form a tetrahedron. This was, in turn, enclosed in the aeroshell. The airbag system that would cushion the landing (see right) was attached to the outside of the lander, and the whole MER assembly attached by tether to the retrorocket and braking parachute unit.

Soft-landing a robot on the surface of an extremely difficult task, as the nur failed landers attests. With just one pi of the density of Earth's atmosphere, Martian air is too thin for a parachute completely slow down an incoming pi MER combined a descent parachute w two other innovations. A cluster of airbags inflated around the lander during its final stages of descent, while a retrorocket unit suspended in-between the parachute and the cushioned lander fired just above the surface to help slow the speed of impact. Once they had stopped bouncing, the airbags deflated, and powerful motors in the lander unit's "petals" pushed the vehicle into a horizontal position.

OPPORTUNITY ON MARS

An artist's impression places the Opportunity MER on the edge of a genuine photograph of Victoria Crater. The Mars Reconnaissance Orbiter spotted the rover here shortly after its arrival in 2006 (see p.283).

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Getting Started With Solar

Getting Started With Solar

Do we really want the one thing that gives us its resources unconditionally to suffer even more than it is suffering now? Nature, is a part of our being from the earliest human days. We respect Nature and it gives us its bounty, but in the recent past greedy money hungry corporations have made us all so destructive, so wasteful.

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