Mission to Mars

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) Why does Mars have bigger volcanoes than the Earth?

Credit: Lunar and Planetary Institute

The Tharsis region of Mars with a map of the western United States for scale. Olympus Mons is the volcano at upper left.

Martian volcanoes are not currently active as far as we can tell but some of them must have been quite recently (at geological scale), which means about 1 million years ago or less. Are they extinct or only dormant? No one can tell with volcanoes…and we are still looking for a spectral signature that could show us a region of heat on Mars. We'll see. As you said, these volcanoes are quite big compared to the Earth's volcanoes. Although you probably have heard a lot about Olympus Mons and all the Tharsis montes, which are really big, there are all sorts of volcanoes on Mars. Many of them are about the size of those found on our planet. Now, what the Martian volcanoes are not: they are not created by subduction which requires moving plates. Lots of volcanism on Earth happens on, or at, the margins of continental plates. Plates are moving and because of that it is hard for terrestrial volcanoes to build large structures. Look at the Hawaiian Islands. There is a very active hot spot right below. The magma is coming up at the surface and has been coming up for some time. However, since the plate on which the islands are formed is moving away from the hot spot, what happens is that (1) the volcano gets disconnected from its source of magma, is not active anymore, thus does not grow anymore, and (2) as the plate slides, the magma will find a way up to the surface through the Earth's crust and another volcano will be formed. Because the hot spot is at the same place and because the movement of plates is somewhat homogeneous, in time a chain of aligned volcanic islands is created. These volcanoes are big, all right, but not as big as on Mars because they do not have time to grow as they are rapidly disconnected from their source of magma. On Mars, there is no plate tectonic. Martian volcanoes are due to hot spot volcanism. Once the magma has found its way out by one point, it will tend to always get out by the same point. Therefore, volcanic structures will tend to be higher than on Earth (see the cartoon I made for you below). Finally, for your information…on Earth, do you know how fast the continental plate that supports America is moving away from the African plate? Well the answer is at the tip of your fingers. It is moving as fast as your finger nails are growing!

2) How old is Mars?

Mars is the same age as our Earth. All the planets were formed at the same time about 4.5 billion years ago (4.5,000,000,000 years) out of the solar system nebula material. When the Sun was in its infancy, it was surrounded by a large, orbiting cloud of gas and material. The material in the gas was mostly composed of grains of dust and ice. Little by little, these grains of dust and ice started to collide with each other, forming small clusters, then larger clusters. They became very large, to the point that they formed what we call "proto-planets" and then the planets as we know them. The planets in our solar system were all formed at the same time. They do not necessarily look alike and their composition is often different. This is due to their location in the solar system --more or less far from the Sun. They may contain more ice or less ice, more gas or less gas. It is also because of their mass. The larger a planet, the better its ability to retain an atmosphere; the farther it is from the Sun, the colder it will be. But it is still the same family and they also have in common their age. Now, speaking of age…do you know what age you would be on Mars? Mars is farther away from the Sun so it takes the Red Planet longer than the Earth to complete a revolution around the Sun. So, a Martian year is longer.

3) Is there a sufficient water supply on Mars?

Credit: NASA/JPL/Malin Space Science Systems

Gullies on Mars discovered by the Mars Global Surveyor.

Well, this is a very interesting question. This is exactly what is driving NASA to explore Mars so intensely. Water is so important…for many things. First, it is important for life. We know that where there is life, there is water. Now, where there is water, there is not necessarily life. But it is a good start as life needs water for about everything: survival, chemical processes, etc. Is there water on Mars? Yes! We know that for sure because we have observed that the north pole of Mars is composed of water ice. If the northern polar cap was to melt, I believe it would be equivalent to 70% of the Earth's Arctic ocean. This is a lot of water. The problem…It's ice right now! To make liquid water available, we would have to spend lots of energy to melt the ice. So, is there liquid water on Mars today? Researchers have found much evidence of traces of ancient activity of liquid water, like valley networks, outflows, dry lakes, "sploch" craters which have large lobate ejecta which shows that comets and asteroids impacted a subsurface rich in ice or water. There is also tantalizing evidence of a much more recent activity with the gullies that Mars Global Surveyor discovered. But so far, we have not seen a pond of liquid water at the surface today. The main reason is because the atmosphere of Mars is so thin that if you put a bucket of water at the surface, it will evaporate immediately. So, if there is liquid water on Mars, where could it be? Underground is probably the right answer…How deep? If we want to find large reservoirs, we will probably have to drill and build deep wells and pump the water maybe down to 500 m or more. For smaller reservoirs, it is possible that old "trapped" water reservoirs could be much higher than that, only few tens of meters from the surface. This is where Mars Odyssey (MO) is playing such an important role. It has onboard an instrument that is capable of identifying Hydrogen. You know that water is composed of two atoms of hydrogen and one atom of oxygen (H20), right? Very recently, MO has found a very large abundance of hydrogen in the very shallow subsurface of Mars. Is this ice? Is this water? Is this the signature of aqueous minerals (formed in a water environment)? What we know so far is that this is good news in the search for water.

4) How will water be distributed when we are living on Mars?

I suppose that you are wondering how we would use the water on Mars? If humans one day settle on Mars, it means that we will have found enough water to make a colony possible. It also means that we will have the technology to extract the water from the subsurface or from surface ice. How we will use it. There are some fundamental uses that nobody can avoid: (1) survival:
a human being in average drinks 2-liters of water per day (about half gallon); (2) agriculture (in greenhouses): it is likely that astronauts on Mars will grow plants to eat to have enough independence from Earth so that they can survive if cargos are delayed. This requires lots of water too;
(3) rocket fuel: water is important for astronauts to generate their own power. If they can make their own rocket fuel, it means that the cost of a mission to Mars would be half of what it costs now for fuel. If they do not need to take the water from Earth to drink and to cultivate plants, that will save a lot of mass that needs to be launched as well as a lot of money (the bigger the rocket you need, the more expensive it is). It is likely that the first colony will have a controlled consumption of water. This fluid that is so common on Earth will be like gold on Mars…unless we discover very large reservoirs.

5) I'm confused. If we land on Mars, what would we look for to find life on Mars? What is so exciting about bacteria?

The size or the type of life is not what is important. Finding the smallest, simplest but unambigous trace of life on Mars would be the greatest discovery made by humankind in its entire history. It would mean that life did not appear only on Earth. It would mean that out of 9 planets in our Solar System, at least already two planets developed living organisms. I am not sure that we could yet conclude that life is a common occurrence in the Universe, but it would definitely increase the odds that this is just the case. What an amazing discovery. What an amazing perspective. But this discovery would be just the beginning. Fascinating questions would follow: If life on Mars is similar to forms of life on Earth, what would that mean? Could two different planets have developed independently similar forms of life (separate genesis)? It could be that trying to solve the same questions of survival, life came up with the same strategies; Could it be that we are distant cousins?

We know that lots of material (rocks) were traveling from one planet to the other at the time of their formation. Large asteroids were impacting both, ejecting rocks that travelled through space and landed either on Mars or Earth. This is called "exchange of material between planets". So, could it be that life appeared on one of them and took a "lift" to the other where it developed too. Some bacteria are good candidates for this type of survival. The next fascinating question would be then: Did life on Mars in fact originate on Earth? Or are we, Earthlings, in fact Martians? It is also possible that the types of life will be different, clearly showing two different starts. It is also possible that life never appeared on Mars. We will have to search and we will search for what we know are the absolute pre-requisite for life as we know it: water, energy, and nutrients. We will search for places that show these ingredients in the past. This is what the Mars Rovers will be doing.

We also at some point in the future will be searching for places where the new missions are currently showing intriguing signs that water or ice could still be there and not too far from the surface. If life developed on Mars, it was faced with even greater challenges for survival than us on Earth: more dramatic climate changes, harsh environment, and the loss of the atmosphere through time. Simpler organisms could have been better at reacting to such changes because they are usually less fragile than more elaborated forms of life. However, who knows? A great attribute of life is that it is adaptable and resourceful. This is why the quest is so fascinating.

6) Why is Mars so cold?

Pathfinder panorama of Mars with Sun on the horizon.

There are several reasons. The first one is because the planet is farther away from the sun than Earth is. You can see the diameter of the sun in the Pathfinder landing site panoramas. Although the landscape looks very much like Earth, the notable difference is the size of the sun's disk in the sky. That tells you that Mars is farther away. For the same surface area, Mars receives 2.5 times less energy than Earth. Another reason is because Mars has a very thin atmosphere and not much cloud cover. During summer in the equatorial regions, Mars has very nice temperatures during the day that can go up to more than 25° Celsius (77° Fahrenheit). However, as soon as the afternoon ends, all this heat goes away very quickly because the air is thin and there are no clouds to temperate the fall of the temperatures like on Earth. Then, you go in few hours from plus 25° Celsius to minus 50° Celsius (minus 58° Fahrenheit)! As far as winter is concerned, it is really cold. It can go down to minus 120° Celsius (minus 184° Fahrenheit) near the South Pole. This is so cold that even carbon dioxide freezes there.

7) What are some facts about Olympus Mons? How large is the area it covers?

Olympus Mons is the largest volcano of the solar system. It reaches 26,000 meters high. To get that high, you would need to stack 3 Mount Everest on top of each of other! It is, alone, 500 km wide. I believe that if we were to have such a volcano in the United States, it would cover two-thirds of Texas! From there, you also realize that it is not a very steep volcano. To get to the top, you would have a very long, but not so hard hike up. Tell me about the view! To the North, ancient lava flows extending as far as you can see and very, very far away, the Northern Plains of Mars with the contact of the Plateau and the Plain. To the east, ancient lava flows and the gigantic Valles Marineris, extending like a 5000-km long scar in the martian crust. To the South, the martian highlands and the traces of ancient rivers and lakes, many evidence of the past activity of Mars. To the west, the ancient lava flows would fade out, and the scarp would open the view on Mangala Valles, a gigantic outflow which runs into the plain. Definitely worth the hike!

8) Why is Earth's core still hot? What is the core of Mars like?

Two questions in one here. All right! Let's start with the Earth. Of course, the core is the central part of planets, the deepest. You can imagine the pressure down there. But there is more than that. What keeps the core hot is related to the radioactivity of the rocks. Radioactivity is the breaking up of particles or nuclei into smaller one. This is happening at very high speed, the particles hit each other and in the process they are heated. To give you a better idea, imagine on a larger scale how this could translate. If you imagine an asteroid hitting the earth at high speed, you can picture that this will release lots of heat. Same thing here, except that the scale is much, much smaller. This is the source of heat in the Earth that keeps the core hot. Of course, Earth is cooling down with time as the radioactivity of rocks decreases but, do not worry: the sun will disappear before Earth's resources are exhausted. Below are two sites on the web that you can go to if you want to learn more about the Earth's core. There are many sites, all very interesting. So, dive in!

Learn about the Earth's interior

Learn about the Earth's core

Now Mars. The truth is that we do not know much about Mars' core although we believe that, like Earth, the Red Planet may have a largely iron core. The difficulty resides in the fact that we do not have yet any seismological evidence, the dimensions, composition, and physical state of the core. We need to put stations on Mars to study it. However, some people are noneless trying to understand it better even before we install those stations on Mars. They are finding clues in the Martian meteorites where the presence of iron sulfide could suggest that iron and sulfur are components of the core of Mars. A group of people have put together a cool experience to try to understand what is happening on Mars from their lab. You will see what scientists do when they cannot always access the field directly.

The recent missions also provide some clues. For instance, the fact that the Mars Global Surveyor discovered magnetic stripes in the ancient terrain of Mars seems to indicate that the iron-rich core probably formed during the hot accretion of Mars 4.5 billion years ago and subsequently cooled at a faster rate than Earth's core. They believe from the study of the data that, today, Mars has probably a liquid outer core and a solid inner core like Earth.

Currently, the Europeans are preparing a mission named NETLANDER that will be launched in 2007 and will land a network of 4 geophysical and meteorological landers that should give us critical information about the internal structure of Mars.

9) How long is a year on Mars?

Mars must travel a greater distance than the Earth in order to complete one orbit around the Sun. Therefore, a Martian year is much longer than an Earth year.

The Mars year is equivalent to 687 Earth days. The martian day is called a "sol" and is about 24 hours and 40 minutes, which means that the Mars year is about 668 sols. You would have to wait longer to celebrate your birthday on Mars.