Landing on another planet is extremely difficult. Landing on a large planet with significant atmosphere is even more difficult. And, if something goes wrong on a spacecraft while it is landing, even the slightest error can cause disaster for the mission.

This post will be about Beagle 2, an ill-fated but extremely cool and innovative Mars lander from 2003. It's one of the many examples of why landing on Mars is extremely difficult, and also an example of why total failure of a mission doesn't necessarily mean the end.

Rendition of Beagle 2 on Mars
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Landing on Mars

The planet Mars has an unfortunate combination of characteristics that make it quite difficult to land things on the surface without destroying them. Unlike the moon, Mars has a significant atmosphere (mostly carbon dioxide) with a surface pressure about 200 times less than Earth's sea level pressure (600 Pa vs. 101300 Pa). Even though this pressure is very low by our standards, the atmosphere is dense enough to burn up spacecraft if they get too close to the planet at orbital speeds (typically a few kilometers per second at Mars).

The atmosphere is at a perfectly terrible spot where it is thick enough to require special design and shielding but too thin to make parachutes effective. Because of this, spacecraft relying on parachutes to land must use very large parachutes and keep the spacecraft mass very low.

The planet itself is also somewhat large, with surface gravity being about 1/3 that of Earth. This means that objects trying to land on the surface will be a lot heavier than they would be on the moon or an asteroid. Throw in the atmosphere and you have an extremely difficult engineering problem.

To successfully land on Mars, the Opportunity and Spirit rovers used this giant airbag assembly to survive impact.
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The subject of this post, Beagle 2, utilized a low spacecraft mass and big parachute to try and land on Mars.

The Beagle 2 Mission Overview

Beagle 2 was the UK's first (and only) attempt to land on Mars. This very cool spacecraft was a small lander with a mass of several dozen kilograms and traveled to Mars onboard the ESA Mars Express spacecraft in 2003. Mars Express is a currently active, much larger Mars orbiting spacecraft developed to study the surface and atmosphere of the planet below. Today, Mars Express is the second oldest active Mars orbiter, behind a NASA spacecraft. Beagle 2, unfortunately, was not so lucky.

The Mars Express orbiter.
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The Beagle 2 lander was meant to look for signs of life on the surface of Mars. Solar powered, the 1-meter wide circular lander contained a robotic arm with various sensors onboard that could look for various compounds and elements on the surface. A small device called the Planetary Undersurface Tool could be used to drill into the ground several feet from the lander and return samples to the main spacecraft using a winch. Communications were handled by sending electromagnetic signals up to the Mars Express orbiter high above the surface for transmission back to Earth.

Beagle 2 with its aerodynamic shell still attached
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Because Mars is still somewhat close to the sun, solar panels can be used to produce reasonable amounts of power (although less power is available than on Earth). Beagle 2 used four circular solar panels, folding out in a clamshell design upon landing. These panels would charge onboard batteries and provide all necessary power for surface operations.

Contained within the aerodynamic shell, the lander was built to withstand entry into Mars' atmosphere before jettisoning the shell and landing via parachutes and airbags. Once on the surface, the spacecraft was meant to unfold its four clamshell solar panels and instrumental panel, take pictures of the surface, and begin surface science operations.

Rendition of Beagle 2 on Mars
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Mission Timeline

Mars Express, with Beagle 2 onboard, launched from Baikonur cosmodrome in Kazakhstan in the summer of 2003, sending the two spacecraft on a trajectory to the red planet. A Soyuz launch vehicle carried both spacecraft off of Earth.

A similar Soyuz launch carried Mars Express.
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Months later, in mid-December 2003, the pair arrived at Mars. Beagle 2 was ejected from the Mars Express spacecraft - while Mars Express would be inserted into an endless orbit around Mars, Beagle 2 would go to the surface. On Christmas day, 2003, the lander impacted the atmosphere of Mars. The heat shield was necessary to protect the spacecraft from being totally destroyed by atmospheric entry, since the spacecraft was moving at several kilometers per second relative to the atmosphere.

The parachute slowed down the lander, the airbags deployed, and the vehicle touched down on the surface of Mars. At this point, something went wrong. The spacecraft never sent its scheduled transmission later that day. Despite several attempts to listen for the spacecraft from Mars Express (which had successfully entered orbit), Beagle 2 was never heard from again.

Beagle 2 Landing
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Beagle 2 was yet another Mars lander to fail prematurely. The environment is incredibly harsh, with dust storms, extreme cold, little sunlight, and very low atmospheric pressures - not to mention the ridiculously harsh re-entry environment upon entry into the atmosphere from a flyby trajectory. It joins a long list of Soviet, American, and European Mars landers to fail, including the recent Schiaparelli lander, which crashed into the surface last year.

Re-discovery

The fate of Beagle 2 was somewhat unknown after its disappearance. Attempts to find the spacecraft using satellite images were unsuccessful. Possible scenarios involved everything ranging from the lander burning up and never reaching the surface, to the lander successfully landing but being unable to deploy due to an encounter with the falling parachute. With no transmissions, it was impossible to tell for sure what had actually happened.

Then, in 2015, the incredible happened: Beagle 2 was found. The NASA Mars Reconnaissance Orbiter (MRO) orbiter took a picture of the surface that was identified to contain the remains of the Beagle 2 lander. This should amaze you - a 1 meter wide object on the surface of a huge planet millions of miles away was located by the cameras of a giant flying robot the size of a car orbiting the planet itself.

And here, 11 years later, are the pictures of what happened to Beagle 2:

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As you can see, the spacecraft made it to the surface in one piece! However, you can clearly see that only two of the four solar panel discs actually deployed. Because the UHF transmitting antenna was underneath the solar panels, the failure to deploy the last two panels blocked all possible transmissions. Because of this, it isn't known whether or not the spacecraft actually survived much past landing, as even if it did, Mars Express would not have been able to receive any transmissions.

Beagle 2 will remain down there for a long, long time in its current state. It is likely almost untouched, minus some dust and environmental damage, after its now 15 years on the surface of Mars. There is even speculation that it recorded data that could be recovered if a future rover mission were to land nearby. This means that there is a very slight chance we could see this lander up close once again sometime in the far future. For now, it remains a unique time capsule, to stay on Mars forever - or at least until we go get it.

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I hope you enjoyed this post - After my New Horizons post I've thought it would be fun/interesting to do some spacecraft mission writeups. I really like Beagle 2 because it shows that nothing is ever really lost in space - everything we send up stays up there essentially forever, even if it can't function. It also showcases how ridiculously incredible some of the equipment in space is: This is effectively like locating a single cow that's been lost for a decade from hundreds of kilometers up with an autonomous digital camera, except it's taking place millions of kilometers away from the spacecraft operator.

Let me know if you have any questions, comments, or corrections.

Additional Sources
Beagle 2 Wikipedia Entry
List of Mars landers - Notice the huge amount of failed landings
Atmosphere of Mars Wikipedia Entry
Spaceflightnow Mars Express
Mars Express Wikipedia Entry
NASA Beagle 2 Page
MRO Wikipedia Entry