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Read Some Answers!

Questions mark the beginning of every space science journey. So if you've ever wondered why, where, what, who or how — click the "Ask A Question" button below to find out from the Athena Mission scientists. Read on to discover what other kids have found out!


1) Instead of Mars, why can't we dig up the Moon to find life?

Only those planets and moons that offer or have offered friendly environmental conditions to support living things are promising targets for the search for life. As far as we know, this involves liquid water. Because water in liquid form - as opposed to frozen water - can only exist at a certain pressure as you find on a planet with an atmosphere, our moon cannot support liquid water since there is no air around it to provide this pressure. Also we know from past missions to the Moon that it never ever had any substantial atmosphere for long enough amount of time to allow water to exist as a liquid. Therefore scientists are certain that the Moon never harboured any life.

2) What type of things do humans need to live on Mars?

Humans basically will need what they need on Earth to live: this certainly includes liquid water which is required by all living things as we know them; we will need oxygen at the right pressure so we can breathe; we need food; and, finally, 'comfortable' temperatures. For a few hours, this can be provided in space suits for people working on the surface of Mars, as is routinely happening in space close to the Earth when astronauts work outside the Space Shuttle or the Space Station. But, to live in a convenient environment on Mars for a longer time, 'high tech' buildings (so-called 'habitats') are needed which can hold the air for people to breathe. Oxygen for this air could be generated on Mars from rock and soil that is found there. Water could be excavated as ice from below the surface that is then brought into the habitat to be melted. Energy for heating could be produced by solar cells, using light from the sun. Food, however, may have to be brought from Earth at first, but later on farming could be started inside the habitat. However, a lot of nutrients we eat are from livestock and thus, ultimately, human settlers on Mars may have to raise their own cattle inside their habitats!

3) How long does it take to get from Earth to Mars?

The flight time to get to Mars from Earth depends on the alignment of the two planets as they both move around the Sun at different distances and different speeds. To be fuel-and cost-economical (meaning being able to launch with a rather small rocket), flights to Mars can begin only about every 26 months. Currently, unmanned space probes sent to Mars are accelerated to their initial speed by the launch vehicle (rocket with several stages) and then continue to Mars without power in a flight that lasts between 6 and 11 months, depending on the year of launch. For later missions, also by humans, it may be desirable to cut this flight time by continuing to accelerate with rocket engines during the flight. This will require new types of engines that have sufficient thrust force while also using little fuel. Before these are ready, more development work is needed. Once available, these 'in-space propulsion systems' could allow a flight to Mars within maybe 2 to 3 months.

4) Does Mars have both dust and sand? Why?

Dust and sand both consist of particles that are created when larger rocks are broken to pieces by different processes of erosion. Sand particles are larger than dust particles (by as much as a factor of 100) and also are typically quite rounded. Very often, sand particles are created when water is involved in grinding rocks into small pieces. They can also be formed by the abrasive action of wind on rocks. Dust particles are usually rather flat and irregular in shape and are often formed by chemical 'weathering' of rocks, are ejected out of volcanoes, or are created by impacts of meteorites into a rock surface, as frequently happens on planets or moons which are not protected by an atmosphere. Mars has both dust and sand, just like Earth. We can tell because we can observe phenomena on the surface of Mars that are typical for dust and for sand, respectively: we can see dust suspended in the atmosphere of Mars and estimate the particle size by studying how sunlight is scattered by them. On the other hand, we see dunes on the surface that must be accumulations of sand-sized particles which - like on Earth - are transported by winds in 'hopping' motions along the surface. This similarity with Earth reflects the fact that both planets have an atmosphere which will transport sand and dust in their respective modes of movement. Moreover, the existence of sand may point towards the action of liquid water in Mars' past.

5) What will happen if an asteroid hits Mars?

Impacts of asteroids and meteorites onto planets and moons in our solar system is a common process. Although most of such impacts happened early in the history of the s olar system, impacts can still occur today but quite rarely and by rather small objects (this is because most of the larger remnants of planetary formation have been 'consumed' as impactors by now). An impact of an asteroid onto Mars would be rather unlikely since the actual asteroids orbit in rather well-confined orbits and normally will not lead to collisions with the planets. But if an object of, say, a few kilometers in diameter were to impact with Mars - or the Earth - the consequences would be severe, because of the large velocities involved which result from the different orbits of the target and the impactor. A crater of at least tens of km diameter would be created in a matter of a few seconds, and large shock waves would spread out in the planet's atmosphere. Such an impact on Mars - and mainly its aftermath - would probably be observable by telescopes on the Earth. A similar event took place about 8 years ago when several pieces of a comet - all a few kilometers in size - impacted with the planet Jupiter and disrupted its atmosphere for weeks.