Mars Landing is very difficult. But Why? We explain in details.

The Red Planet Landing.

Ever since humans landed on the Moon, we have dreamt and worked on ways to reach the Red Planet, Mars. There have been many attempts for a Mars landing and many Mars landing missions such as The Vikings from NASA, the Mars 2 and Mars 3 from the Soviet Union, Japan’s Nozomi and the European Space Agency’s Beagle 2. But majority of these Mars Missions have failed. In fact, only two countries have successfully achieved Mars landing. Out of all these space agencies, NASA’s Mars landings have been the most successful. The recent InSight from NASA was another feather in its cap.

But why did these advanced countries like Japan and the European Union failed in landing a machine on the Martian surface? This is what we are going to explain. Why landing on Mars is a nightmare for scientists. We’ll also go through the entire process of how landing on the Red Planet is achieved. Then we shall look at the future plans of going to Mars and the possibility and feasibility of sending humans to Mars.

What is Mars Landing?

In very simple terms, the whole process is pretty much self-explanatory. It is when a craft is sent into the orbit of a planet or a satellite (moons) and then carefully landed on the surface. Easier said than done and in this case, it is a lot easier said than done. But if it is so difficult to achieve, why must we do it? Because we are curious. And we can, not completely, but we are slowly going up there. 

Sending a orbiting satellite is much easier and there are many at this time, revolving around Mars. But there’s only so much we can do from above the planet. For studying the planet closely, we have to land on its surface. Not just land, but companies like SpaceX and organization like NASA are planning to send the first humans to the Red Planet. So it is imperative that we learn to land a craft on the surface. 

How Mars landing is achieved?

Using retrorockets to slow down the lander
Using retrorockets to slow down the lander. Image : NASA

For bare-bone simplicity, the whole structure of how to land on Mars is this: reduce the speed of the craft, find a plain terrain and then gently lay the craft on the surface. But this comes with a million other complexities that scientists and engineers have to take care of. A mission module usually has three components, an orbiter, a lander and a rover.

An orbiter revolves around the planet and identifies suitable place for the lander to land. It also keeps an eye on the rover when it is deployed. 

A lander is a structure that protects the delicate rover from crashing and safely land the rover onto the surface. 

The rover is just a small remote controlled vehicle with very delicate sensors and machines that carry out the investigations and experiments.

Slowing down while landing.

When a spacecraft enters the atmosphere of another planet, it must start slowing down its speed to achieve landing. When the craft enters the planet’s atmosphere, the speed can be as high as 12,500 mph or about 20,000 kmh. To achieve a soft landing, the speed must be reduces to 5 mph or 8 kmh. That is a difference of 2,460 times! All of these must be done very quickly in a crucial timeframe.

To achieve this slowdown, there are multiple technologies that we have used and are testing. While the first common method of slowing down that comes to our mind is the use of parachute. And yes, parachutes are used for speed retardation. But that is not the only method we use. In addition of using parachutes, the landers are also equipped with retrorockets. These rockets fire up in the opposite direction of the motion to counter the massive speed of the lander. 

Mars Landing the rover breaks free
The rover sets free from the lander.

But these methods are not always useful. Using rockets and parachutes increases the wright of the lander, which can be a dangerous and unnecessary addition. So scientists have used various methods to land relatively smaller and lighter crafts. For example, as the lander reaches slower speed, a tetrahedral cocoon of airbags inflates and covers the entire lander. Then it just bounces of the ground. These airbags can be of various shapes, like a donut or a semi-circle, all depending on the shape and size of the lander. To enhance the safety of landing, engineers have used sky-crane which slowly lowers the lander with the use of cables. Pretty neat. 

But all these above-mentioned methods of landing on Mars is not very useful because the way Mars is. Keep in mind that these are the most advanced technology for landing that we have. Let’s see why things are so difficult in Mars.

The Challenges on Mars.

All those methods of landing is not of very use when it comes to Mars landing. Mars happens to be in a not-so-sweet-spot of creating a lot of nuisance for our technology. For every planet, there is a measure for landing the craft, called EDL. EDL stands for Entry Descent and Landing. This is usually the extent of the planet’s atmosphere. So for Earth, the EDL is about 62 miles (100 km). For Venus, the EDL is 155 miles (250 km). But for Mars, the EDL is just 50 miles (80 km). This is what makes things difficult. Once a craft enters the EDL, it must start preparing for landing. Firing retrorockets, deploying parachutes, releasing landing gears.

You must keep in mind that all of this is happening from Earth! And since the speed of light is not infinite, a message from Earth to Mars take about 10 minutes on average (depends on the orbital position of both the planets). Then another 10 minutes for the response to come back to earth. Imagine clicking a link on this page and it takes 20 minutes to register the click! So preplanning and perfect timing is crucial. A small mistake can decimate the entire lander and craft (which actually happened. Discussed later in the article).

The Curiosity Rover
The curiosity Rover. Image : NASA/JPL

Landing on Moon or Venus is much easier than landing on Mars

Since the EDL is so short for Mars, things are much more tense when it comes to landing there. Plus we cannot just land anywhere on Mars. The orbiters and satellites around the red planet surveys the land, its elevation and its softness. Too hard and the lander might crash. Too soft and the rover might get stuck. We have to find the perfect spot for landing. And then comes the Martian atmosphere.

When a craft enters a planet or satellite (moons) with atmosphere, the atmosphere causes the craft to heat up. This can lead to insane amounts of temperature. To avoid this, the crafts are covered with heat shields. These heavy heat shields are important for the functioning of the small and delicate sensors. For planets with no atmosphere or the Moon in this case, there is no atmosphere. So we can skip the heat shield and keep the craft light. Hence, using retrorockets can slow down the lander. 

For planet like Venus, the atmosphere is thick enough for parachute to work. Combine that with retrorockets and the craft can be installed with heat shields (which makes it heavy). Easy landing. Remember, for parachutes and even helicopter (with rotors) to work, there must be ample amount of atmosphere. 

Now when we come to the Martian planet, there is a thin atmosphere, enough to generate heat but not enough to support the use of parachute. This puts engineers in a dilemma. They have to use heat shields that increases the weight, but parachutes aren’t going to help, as Mars has about 1% of Earth’s atmosphere. And hence, the problems being. 

This is why the success rate of landing on Mars is just about 54%. So this is the reason why many countries have failed to land on Mars. Let’s take a look at some of the Mars missions that were successful and some which failed.

Mars Landing. Earth V Mars in size
Earth V Mars in Size.

The Mars Missions 

The first ever attempt to send a probe to Mars was done by Soviet Union in 1962, before Moon landing! The mission, named 1962B failed. But that did not discourage the Soviet Union from trying. In 1971, Soviet Union became the first country to send a probe to Mars. The probes, Mars 2 and Mars 3 were successful but the landers crashed. Mars 3 send the first ever image of the Martian surface but soon died out, most probably due to dust storm. Then there were more probes, named Mars 4,5,6 and 7 to gather more data.

In 1976, NASA sent Viking 1 which successfully landed on Mars. It also send the first color picture of the Red planet. The famous “Face on Mars” image was send by Viking 1.

In 1997, NASA sent the Pathfinder mission which was the first mission that sent a rover on Mars. The rover, named Sojourner took 550 images and 15 chemical analysis. The orbiter took 16,500 images. 

NASA also successfully sent the Mars Reconnaissance Orbiter and the Phoenix Marr craft. During the entry of Phoenix, Mars Reconnaissance Orbiter took the image of the craft. This was the first ever image of a craft taken by another craft. NASA, in 2018 also sent the Mars InSight mission successfully. NASA has been the most successful space agency when it comes to Mars missions.

The Face on Mars by Viking 1
The Face on Mars by Viking 1. Image : NASA

Some Failed Attempts.

Russia’s Mars 96 failed in 1996 and Japan’s Nozomi failed too. One of NASA’s failure, the Mars Climate Orbiter failed because the software at Lockheed Martin (manufacturer of the craft) and NASA were using data in different metric system. Yes, that small error resulted in the wrong trajectory of the orbiter and it was destroyed. The European Space Agency’s Mars Express orbiter and the Beagle 2 rover was a half failure as the rover did not make it. But the Mars Express orbiter tested positive for water ice and carbon dioxide ice on the South Pole of Mars.

The Beagle 2 rover was detected in 2013 by NASA’s Mars Reconnaissance orbiter. The reason for the failure of Beagle rover was it did not deploy its complete power.

The Future Mars Missions.

Many other countries are planning to pay a visit to Mars. We have China with its Mars Global Remote Sensing Orbiter and small rover planned for the future. Then there’s India’s Mars Orbiter Mission 2 and ESA’s ExoMars rover mission. The most interesting is NASA’s Mars 2020 mission. 

Why Mars 2020 mission is special.

NASA’s Mars 2020 mission is so very interesting because this will be the first mission when humans will achieve powered flight on another planet! NASA is sending a Mars helicopter that will fly for about 90 seconds on Mars. You can watch Veritasium’s video on the topic and get into the details of it by clicking here.

Mars Landing. The helicopter for Mars 2020
The Mars helicopter that will fly over the martian surface in Mars 2020 mission. Image : NASA

What makes this mission more interesting is that this will be the first time a craft is going to bring a sample from the Martian surface back to Earth. And the Mars 2020 mission will also be the stepping stone for NASA’s ambitious plans of sending humans on the Red planet! The Artemis program, planned for 2024 will put the first ever woman on the surface of moon (Artemis is the daughter of Zeus). Not just that, the Artemis will use lunar surface as a training ground for the future Mars mission of sending humans in 2030s. All I can say is the next decade and the one after that is going to be an exciting one for spacefaring.

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