What instruments would you place on a robot space probe?
The Viking space probes (Viking 1 and Viking 2) were two NASA missions to explore Mars in the 1970s. Both missions deployed a pair of robot probes: one lander and one orbiter. These probes were very advanced at the time and are still technological marvels today: they are fine examples of human ingenuity. The diagram above shows a Viking lander (landing probe) and a labeled version is given below.
Length: 3m; Height: 2m
Mass (fully fitted): 576 kg
The body platform of each lander is hexagonal and constructed from aluminium and titanium alloys. Three alternate sides are shorter, such that in plan view the body resembles a triangle with blunted corners with a landing leg on each short side. The body is covered in spun fiberglass and Dacron cloth to protect equipment and conserve heat. the lander and external assemblies are painted light grey (with a rubber-based silicone)to protect it against abrasion and reflect solar heat.
Deployment of the Landing Probes
Viking 1 landed on Mars in the Chryse Planitia (Plane of Gold, 22.697 oN) in July 1976.
Viking 2 landed on Mars in the colder Utopia Planitia (Plane of Paradise, 48.269 oN) in September 1976.
The lander (landing probe) and aeroshell separate from the orbiter (orbiting probe), placed in orbit around Mars, and descend. The aeroshell acts as a heat shield and carried out some measurements on the upper atmosphere (composition and ionization). It also possessed 12 hydrazine mono-propellent thrusters to maneuver the lander and direct it to the chosen landing site. The lander and aeroshell were encased in two bioshield valves, which enclosed them like an egg. These ensured that the lander remained sterile during launch and were jettisoned on leaving Earth orbit. Prior to launch, the entire assembly inside the bioshield was sterilised by heating to high temperatures to prevent accidental contamination of Mars by microorganisms from Earth.
the lander was initially connected to the orbiter by an umbiliocal cord during the cruise phase to Mars, which allowed power and data transmission. An additional base cover over the top of the lander (between the lander and the bioshield cap) protected the lander during initial entry. The parachute system and the mortar to fire the chute were situated on top of the lander beneath the base cover.
The descent capsule (consisting of lander, aeroshell and base cover) separated from the orbiter and first traversed the interplanetary medium permeated by the solar wind. The following details the descent of Viking 1. The capsule entered the upper atmosphere of Mars at 250 km altitude at about 1600 km/h, with the aeroshell heat shield directed forwards. Friction between the atmosphere and aeroshell slowed descent and caused temperatures to reach something like 1500 C. The heat shield had a sacrificial outer surface layer which burnt away, as intended, carrying away much of the heat with it. The aeroshell provided some aerodynamic lift at about 30 km. At 6.4 km and 1600 km/h the parachute was deployed and seven seconds later the aeroshell was ejected and the lander's three legs extended. After about a minute the chute had slowed the lander to 60 m/s. At 1200 m the lander's three terminal descent engines ignited and the chute and base cover were jettisoned.
Orbiting Probe Specifications
The orbiter (2 325 kg, 3.3 m in height) was equipped with a visual imaging subsystem (VIS), an infrared thermal mapper (IRTM) and the Mars atmospheric water detector (MAWD). The VIS consisted of a pair of identical cameras and telescopes and was used in imaging and selecting suitable landing sites for the landing probes and to map the planet's surface globally. The IRTM mapped temperatures on the planet's surface, which provided data on surface composition and roughness and internal heat sources, e.g. due to underlying magma pockets. The MAWD was an infrared spectrometer used to map the distribution of water vapour over the planet's surface, providing data on weather and seasons. The orbiter was powered by four solar panels (total surface area 15 m2 and a total span of 9.7 m) and equipped with nitrogen gas thrusters. A Sun sensor maintained lock on the Sun for navigation and orientation (the Sun provided a reference for pitch and yaw). The star Canopus, monitored by the Canopus sensor, was also used as a fixed reference point for roll). The brain of the orbiter consisted of two onboard computers with 4096 (computer) words of plated-wire memory. A moveable 1.5 m dish antenna provided remote high-gain S-band communication with Earth (that is by means of a directed radio beam) while an additional low-gain antenna (operating in all directions) provided communications when nearer to Earth. (S-band is a specified range of microwave frequencies).
Landing Probe Specifications
Did you think to include all these things on your robot probe?