MARS IN FOCUS
by Eben van Zyl

In Canopus of September 1997 I sketched in broad outline a manned trip to Mars. Now Sky and Telescope far April 1999 features the caption "Mars in Focus", so things are hotting up. Sky and Telescope mentions same of the steps that have to be taken to "ready" Mars for Man's first landing, which, according to the dynamics of the orbits of Mars and the Earth, could be slated for July 2018 when the two planets came closest together at opposition, their separation E_a to M_p then being as little as 56 million km. (The date 2025 1 mentioned in the 1997 article is palpably incorrect and I hasten to apologise for this mistake). The favourable or advantageous oppositions recur every 15 years. The spaceship with the explorers on board must be launched when the planetary configuration is such that the Earth is at E_l and Mars at M_l with the Sun at S during January / February 2018.

The spaceship which will have been assembled in orbit around the Earth in the precincts of the International Space Station, now being constructed, will use the "window" in January/February 2018 so that it can easily drift into the Hohmann Transfer Ellipse from E1to Mp . This is the most economical orbit to "lift" the spaceship through the 56 million kilometres between the Earth at Ea to Mars at Mp , i.e. the Earth at aphelion and Mars at perihelion. The trip will take about 200 days.

Oppositions at other points in the two orbits can be as much 102 million kilometres apart. The eccentricity of the Earth's orbit is 0,017. Take the average distance of the Earth from the Sun as I AU. Earth's aphelion distance from the Sun is thus 1 + 0,017 x I, namely 1,017 AU. Mars's average distance is 1,524/lU and the eccentricity of its orbit is 0,093. Therefore Mars's perihelion distance from the Sun is equal to (1,524 - 0,093 x 1,524) AU, ie 1,524 - 0,1417 = 1,382 AU. At opposition with Mars at perihelion M_P and the Earth at aphelion E_a, the distance between the two planets is:

1,382 - 1,017 = 0,3753 AU

= 0,3753 x 149 600 000

= 56,14 million kilometres.

The two planets are furthest apart when opposition takes place with Mars at aphelion M_a and the Earth at perihelion E_p. This distance is

(1,524 + 0,093 x 1,524) - (1 - 0,017) AU,

namely 1,524 + 0,1417 - 0,983

= 1,6657 - 0,983

= 0,6827 Au

= 0,6827 x 149 600 000

= 102 million kilometres.

Once the spaceship has reached escape velocity of 11,2 km per second relative to the Earth, its motors can be shut off and the ship will drift along the transfer ellipse E₁ to M_p. When it reaches Mars at M_p, the Earth will be at E_a,

The spaceship will then go into orbit around Mars and from there it will launch a landing vehicle to take the (wo)men down to the surface of the planet. The first priority is that the landing site will have been correctly chosen. This must be a spot where there is a plentiful supply of water in the form of permafrost, in the Martian soil - the nearer to the equator of Mars, the better. On the equator the midday temperature reaches 27°C, rising from 5°C at l0 AM and falling to 0°C at 3.PM. The Mars Global Surveyor craft has found spots where water must have been abundant in bygone ages. If it is still there in the frozen state in the soil, the hydrogen atoms in the ice molecules will reveal their presence by the way they reflect radar waves from the orbiting monitoring craft. The task of selecting the site where there will be enough water has been allocated to a committee headed by Director Charles Leach of the Jet Propulsion Laboratories' Space and Earth Science programs. He will have to see to it that enough Mars Ascent Vehicles (MAV'S) ferry enough samples into orbit around Mars. The French "Centre National d'Etudes Spatiales " (CNES) is to build craft which will rendezvous with the MAV'S and return the soil samples to Earth for analysis. Methods may be developed for analysing the samples in situ without the necessity of bringing them to Earth.

When the (wo)men land on Mars, they will find, already deployed all the things that are necessary for building their living quarters as well as the items required for the exploration of Mars.

Sunshine is very plentiful on Mars. Solar panels and other items will be sent from Earth during the next 18 years so that the explorers can easily connect the modules together to build their living quarters and also to build a solar power station. That is to say, if such a solar power station has not already been robotically constructed by the time the first landing takes place - a sort of "home from home". The power from the power station will be used to heat the living quarters and will drive the drills to be used in retrieving ice-containing soil.

All the necessary apparatus and reagents for analysing soil and rocks, physically, chemically and geologically will have been sent beforehand and will be ready at hand for use by the explorers.

It is also possible that apparatus for the extraction of hydrogen from the underground ice will have been launched from Earth to the landingsite. This hydrogen and oxygencould be used as fuel for the return journey to Earth which will take place in good time to reach the Earth when the next opposition occurs in 2020. The return journey will take about 180 days so that the explorers will have to leave Mars orbit by the middle of April 2020, after having spent all of 1 year 9 months exploring Mars. (l'm so sorry that I have to live in these primitive times - think of the excitement which lies ahead!).

The more equipment that can be sent in advance to the landing site, the more (wo)men that can be accommodated in the space ship. Some of the food required during the journey can be cultivated hydroponically and this can also be done on the surface of Mars. So, whom should we select to make the journey?

First to stake a claim is the hydroponics expert. He/she will also have to be dietician and chef!

Second and third selections will have to be the two pilots. They must also be experts in radio and electronics.

Fourth, must be the geologist cum physicist, cum chemist cum metallurgist.

Fifth the mining, electrical and mechanical engineer.

Sixth: the medical man, doctor cum dentist cum psychiatrist!

Seventh: and what about an astronomer, who on the surface of Mars will be only one-quarter of Earth's distance from the Minor Planets?

All of the seven (wo)men should be experts in more than one field so as to be able to serve as backups. Most important, they should have to be persons who would make the presence of a psychiatrist unnecessary.

When the spaceship gets back to Earth, it will be left in orbit to be readied for the next expedition and the explorers and the samples which they would bring back will be ferried down to Earth by shuttle craft.

By 2033 when the next favourable opposition after 2018 takes place, technology will have developed to such an extent that Man's first planetary exploration will be considered as very primitive