Page 25 - Robots Androids and Animatrons : 12 Incredible Projects You Can Build

NASA estimates that by the year 2004, 50 percent of extra vehicle
activity (EVA) will be conducted using telerobotics. For a complete
explanation of telerobotics and telepresence, see Chap. 9.
Robotic space probes launched from Earth have provided spec-
tacular views of our neighboring planets in the solar system. And
in this era of tightening budgets, robotic explorers provide the
best value for the taxpayer dollar. Robotic explorer systems can be
built and implemented for a fraction of the cost of manned flights.
Let’s examine one case. The Mars Pathfinder represents a new
generation of small, low-cost spacecraft and explorers.
Mars Pathfinder (Sojourner)
The Mars Pathfinder consists of a lander and rover. It was launched
from Earth in December of 1996 on board a McDonnell Douglas
Delta II rocket and began its journey to Mars. It arrived on Mars on
July 4, 1997.
The Pathfinder did not go into orbit around Mars; instead it flew di-
rectly into Mars’s atmosphere at 17,000 miles per hour (mph)
[27,000 kilometers per hour (km/h) or 7.6 kilometers per second
(km/s)]. To prevent Pathfinder from burning up in the atmosphere,
a combination of a heat shield, parachute, rockets, and airbags was
4 used. Although the landing was cushioned with airbags, Pathfinder
decelerated at 40 gravities (Gs).

Pathfinder landed in an area known as Ares Vallis. This site is at the
mouth of an ancient outflow channel where potentially a large vari-
ety of rocks are within reach of the rover. The rocks would have
settled there, being washed down from the highlands, at a time
when there were floods on Mars. The Pathfinder craft opened up
after landing on Mars (see Fig. 1.1) and released the robotic rover.
The rover on Pathfinder is called Sojourner (see Fig. 1.2). Sojourner
is a new class of small robotic explorers, sometimes called micro-
rovers. It is small, with a weight of 22 pounds (lb) [10.5 kilograms
(kg)], height of 280 millimeters (mm) (10.9″), length of 630 mm
(24.5″), and width of 480 mm (18.7″). The rover has a unique six-
wheel (Rocker-Bogie) drive system developed by Jet Propulsion
Laboratories (JPL) in the late 1980s. The main power for Sojourner
is provided by a solar panel made up of over 200 solar cells. Power
output from the solar array is about 16 watts (W). Sojourner began
exploring the surface of Mars in July 1997. Previously this robot was
known as Rocky IV. The development of this microrover robot went
through several stages and prototypes including Rocky I through
Rocky IV.

Team LRN
Chapter one