Christmas Day, 2003, should have been one of the happiest days of Colin Pillinger's life. It was the day Beagle 2, a spacecraft he conceived of, proposed, and developed, was supposed to land on Mars. But Beagle 2 never called home; the scheduled landing time came and went with no information from the lander and no telemetry to confirm what happened. More than 12 years later, and sadly a year after Pillinger's death, NASA has found Beagle 2.
The HiRISE camera on NASA's Mars Reconnaissance Orbiter is a brilliantly powerful, high resolution camera that has taken some of the most striking, detailed images of Mars we have. And it's not only found clear evidence of Beagle 2 on Isidis Planitia, it looks like Beagle 2 actually landed successfully.
The European Space Agency's Beagle 2 lander was part of the Mars Express program; the original Beagle, of course, was the ship that took Charles Darwin to the Galapagos Islands. Shaped like a shallow bowl 2.13 feet across and just 0.82 feet deep, it was armed with instruments that would look for life through geochemical and atmospheric analyses: a pair of stereo cameras, spectrometers, a microscope, and a mechanical mole instrument designed to bore into Mars's soil.
To reach its landing site on Isidis Planitia, a low altitude site that would allow for significant aerodynamic braking, Beagle 2 had planned to use tried and true technologies. A heat shield would protect it from the searing heat of atmospheric entry, then fall away as a drogue parachute deployed, pulling the main parachute out after it. A tenth of a mile from the surface, airbags would have inflated around the lander like a cocoon. As soon as it hit the surface, the parachute would have separated and the lander would have bounced and rolled to a stop, righting itself by virtue of its hinged cover; regardless of its landing orientation, the cover opening would have righted it.
But there were risks taken with Beagle 2's development. The parachute for Beagle 2 was developed in just 15 weeks, and just two were made, one for the flight and one for testing in the Arizona desert. The latter passed a series of drop, tow, and extraction tests, though not in simulated Martian atmospheric conditions.
The airbags built to ensconce Beagle 2 in a cocoon of safety were only tested once. The inflated bags were dropped straight down onto a flat surface, hardly the conditions you would expect them to find on Mars. By comparison, the airbags NASA used for its MER rovers Spirit and Opportunity were tested hundreds of times on varying surfaces at different angles.
But more problematic, perhaps, than the limited testing was the lack of contact with Beagle 2 during landing. The last contact ESA had with the spacecraft was on December 19, the day it separated from the Mars Express Orbiter. It was in good shape, and everything looked good for landing. Then the time came for contact from the surface, and all we got was radio silence.
Attempts to find Beagle 2, or its remains, in images of its target landing area from orbit have been unsuccessful until now. The spacecraft's planned landing area was 105 x 62 miles, a significant area to cover. Complicating the task is the spacecraft's small size. It was incredibly hard to see in any orbital images, but not impossible.
The initial indication that Beagle 2 had been found came from HiRISE images taken on February 28, 2013 and June 29, 2014. Michael Croon, a former member of ESA's Mars Express operations team, thought he saw a good candidate for Beagle 2 near the edge of a frame and submitted a request through the public targeting program to have the site rephotographed.
Subsequent images showed a bright spot moving around, something you might see as the angle of the Sun on solar panels changes with the time and day and time of year. What might be the parachute and the rear portion of the spacecraft's entry cover might have been found nearby as well.
From the imaging data, it looks like Beagle 2 might have only partially deployed, which could explain why it never sent a signal back after reaching the surface; the lander needed to have its solar panels deployed all the way for its antenna to work. Or it's possible the light is bouncing off some solar panels differently than others because it's at an angle. The HiRISE team will have to wait for followup images to confirm exactly what's shape Beagle 2 is in.
Finding a lost spacecraft on Mars is sort of amazing, but it unfortunately doesn't answer the question of what happened to Beagle 2. It's still possible that the airbags failed, leading to extensive damage from a hard landing. It could have succumbed to some electrical or mechanical failure—there was no shortage of moving parts on that spacecraft. Any one malfunctioning could have set off a crippling chain of events.
We might never know the story of Beagle 2 until we send astronauts to check it out up close. But at any rate, finding the lander apparently intact is sort of a bittersweet development. We found the spacecraft, and found that it almost worked!