Man’s fascination with Mars goes back millennia. Mars is also one the few heavenly bodies on which we see surface features; these have inspired the imagination of everyone from scientists, to artists, to writers.
The records of Martian observation date back to the 2nd millennium BC when Egyptian astronomers observed the planet and recorded its position. It was portrayed on the ceiling of the tomb of Seti I (1290–1279 BC). Aided by his telescope, Galileo observed the phases of Mars in 1610. Huyghens produced the first sketches of surface detail in 1659, and in 1660 suggested a rotation period of 24 hours. In 1783, Sir William Herschel detected seasonal variation in the sizes of the polar caps and determined the position of the axis of rotation. In 1877, GV Schiaparelli made the first comprehensive triangulation of the surface and he recorded a number of line-like markings, which he called “canali”. The term was originally mistranslated into English as “canals” (instead of “channels”). As the term suggested intelligent life, this sparked ideas about life on Mars. By 1897 scientists found that the channels were optical illusions.
The Soviets launched several spacecraft to explore Mars from 1960 to 1973, orbiter spacecraft started sending back images and data about Martian gravity and magnetic fields. NASA’s Jet Propulsion Laboratory launched Mariner 3 and Mariner 4 in 1964. Only Mariner 4 launched successfully, it completed a 7½ month journey to Mars passing on 14 July 1965. It provided the first close-up photographs of another planet. In 1975, NASA sent Viking 1 and 2. Each space probe was composed of an orbiter, designed to photograph the surface of Mars from orbit, and a lander, designed to study the surface of the planet. NASA’s Mars Global Surveyor launched in November 1996. It housed scientific instruments which collected data until 2006. The Mars Pathfinder spacecraft landed in 1997, it consisted of a lander and a wheeled robotic rover called Sojourner.
NASA’s Curiosity rover landed on the surface on 6 August 2012 – it’s still there. Its goals are to investigate the Martian climate and geology, see whether Mars ever supported life, and to perform habitability studies in preparation for human exploration. It carries 80kg of scientific instruments and is powered by a radioisotope thermoelectric generator (RTG), it’s similar in size to a small car. The RTG obtains its power from radioactive decay of plutonium-236. Curiosity has: environmental monitoring; alpha-particle x-ray spectrometer device; x-ray power diffraction and fluorescent instrument; and Dynamic Albedo of Neutrons for measuring hydrogen, ice and water. Many of the instruments were developed and funded by agencies from different countries.
Although Mars is perhaps the most discussed planet, the whole of space is of course an area of fascination. From 1981-2011 six Space Shuttle Orbiter’s carried astronauts and payloads into low Earth orbit and performed in-space operations, they were all reusable.
They were powered by 3 Rocketdyne Block 2-A RS-25 liquid-fuelled rocket engines of 393,800 lbf each, with a maximum speed of 17,321 mph. The orbiter carried most of the Space Shuttle System’s liquid-fuelled rocket propulsion system, but both the liquid hydrogen fuel and the liquid oxygen oxidizer for its three main rocket engines were fed from an external cryogenic propellant tank. Additionally, two reusable solid rocket boosters provided additional thrust for the first few minutes of launch. The orbiters carried hypergolic propellants for their RCS thrusters and Orbital Manoeuvring System engines. Three Space Shuttle Main Engines were mounted on the orbiter’s aft fuselage. They could be swivelled during the rocket-powered ascent of the orbiter, so to change the direction of their thrust. The aft fuselage also housed three auxiliary power units, these chemically converted hydrazine fuel from a liquid state to a gas state, powering a hydraulic pump which supplied pressure for all of the hydraulic systems for example, landing gear elements.
The exploration of Mars has come at a considerable financial cost with roughly two-thirds of all spacecraft destined for Mars failing before completing their missions, some before they began. This is due to the complexity and large number of variables involved, and has led researchers to speak of The Great Galactic Ghoul which subsists on a diet of Mars probes!
Despite this, new nations have begun exploration. India’s Mars Orbiter Mission is one of the least expensive interplanetary missions ever undertaken (US$73 million). The United Arab Emirates “Hope Probe” is scheduled for launch in 2020, it is an uncrewed exploratory probe that will study Mars’ atmosphere in detail.
There are still many financial, engineering, physiological and psychological challenges before manned missions become a reality. But the discoveries and technologies of astronomers, scientists and engineers will hopefully help human beings to walk on the red planet.