麻豆传媒

AN AMBITIOUS goal, a brave attempt and a glorious failure. Perhaps that鈥檚 how the public will remember Beagle 2, the low-cost, high-risk mission to hunt for life on Mars. In spite of the fact that the British-built lander disappeared last December, shortly after it had arrived at the Red Planet, it captured the public imagination in the UK like no other spacecraft in recent times.

Even in the face of the loss, the team behind Beagle 2 has remained remarkably upbeat. 鈥淲e鈥檝e learned a huge amount from this mission,鈥� says Mark Sims, the lander project manager at the University of Leicester in the UK. 鈥淭here have been many successes.鈥� There is even talk of a second attempt in 2007.

But this optimism hides another side of the Beagle 2 story. With the clarity of hindsight, the rosy glow is beginning to fade from the tiny Mars lander. Last month, the European Space Agency (ESA) began an investigation into the loss of the spacecraft. The inquiry will attempt to identify any shortcomings in the probe鈥檚 design, and to see what factors might have led to the failure. They may not have far to look.

A number of theories have emerged. One line of thought is that the craft crashed because there is something about conditions on Mars that we don鈥檛 quite understand. Perhaps the surface was more rocky than predicted, making a safe touchdown difficult. Or perhaps the atmosphere was less dense than expected, so that the lander鈥檚 parachutes didn鈥檛 work properly and it hit the ground too hard. There is evidence from NASA鈥檚 landers that this might have been the case.

But another line of thought is that the answer may lie much closer to home. The thinking is that there was something terribly wrong with the spacecraft before it left Earth, and that funding problems, particularly in Beagle鈥檚 early phases, led to management shortcomings and design oversights that doomed the craft to failure. This idea is gaining support as a remarkable story emerges of how in the project鈥檚 final months engineers discovered serious flaws in Beagle鈥檚 design and battled against crushing deadlines to modify the spacecraft in time for launch.

Beagle 2 was conceived in the mid-90s in a worldwide atmosphere of excitement about the Red Planet. In August 1996, the journal Science published research by scientists who claimed to have found evidence of fossilised life in a Martian meteorite. Less than a year later, NASA鈥檚 Mars Pathfinder mission deployed a small rover on the surface for the knockdown price of $265 million. Unfortunately the mission wasn鈥檛 there to hunt for signs of life, but by then the idea that somebody should start looking had taken firm root in the mind of Colin Pillinger, head of planetary and space sciences at the Open University in Milton Keynes, UK.

At about this time, ESA decided to take advantage of a close approach between Earth and Mars in 2003 by sending its first mission to the Red Planet. Inspired by the success of NASA鈥檚 cut-price Pathfinder, ESA reasoned that it too should make its Mars shot a low-cost mission. By copying various instruments from another probe and by contracting much of the work to industry for a fixed price, the agency believed it could build the spacecraft for the bargain price of approximately $160 million.

ESA called the mission Mars Express. To be ready for launch in June 2003, the spacecraft would have to be designed and built in record time. It was to be an orbiter, but the agency left open the possibility that it could carry a single lander weighing 60 kilograms. There was one proviso, however. The lander would have to be funded entirely by outside contributions 鈥� there would be no money from the space agency.

Pillinger immediately took his chance and began the task of raising the money to build a lander, which he expected to cost around 拢25 million. He named it Beagle 2, the successor to the ship that carried Charles Darwin on the voyage that inspired his theory of evolution.

Fund-raising became a key part of Pillinger鈥檚 role. By mid-1999, he had persuaded a number of academic and industrial partners to contribute time and expertise, but cash was proving difficult to come by. Then came a breakthrough 鈥� the UK government agreed to stump up a crucial 拢5 million.

This kick-started the fund-raising, and by the end of the design phase in late 1999 Pillinger had secured another 拢15 million worth of contributions in kind. An infectious enthusiasm and never-say-die attitude took hold among the team. 鈥淚t was extraordinary to be involved,鈥� recalls Ian Stewart, a parachute designer at Lindstrand Balloons in Shropshire, UK, who worked on the craft. 鈥淢any people were effectively working for nothing because they believed in the goals.鈥�

A meeting of minds

With industrial and academic partners contributing on an ad hoc basis, an unusual management structure evolved. The University of Leicester took responsibility for Beagle 2鈥檚 scientific instruments, the European space and satellite company, Astrium, was responsible for the lander鈥檚 computing, communications and power systems, and the aircraft ejector seat specialist Martin-Baker, based near Uxbridge in the UK, took on the landing and descent system. Unusually, these partners took on roughly equal roles in the project, with a web of gentlemen鈥檚 agreements binding them together. Crucially, no firm was given overall responsibility for the spacecraft.

The first cracks in the enterprise appeared in the project to build the landing system, which was based on the exotic method pioneered by the Pathfinder mission. First a parachute slowed its descent and then airbags inflated to cushion the impact with the surface. The idea was simple, cheap and seemed perfect for Beagle 2.

To make the airbag system, Martin-Baker approached ILC Dover, the Delaware-based company that built Pathfinder鈥檚 airbags and which was working on airbags for NASA鈥檚 Spirit and Opportunity rovers. Engineers at ILC Dover were immediately worried by the approach being taken with Beagle. 鈥淲e had a number of concerns about their design,鈥� says Philip Spampinato, product manager for space systems at ILC Dover. The basic measure of an airbag system鈥檚 ability to protect a spacecraft is the mass allocated to it. This determines factors such as size, volume, and how many protective layers the airbags have. In comparison with ILC鈥檚 previous designs, Beagle鈥檚 airbag protection seemed optimistic. While the airbag system for NASA鈥檚 Spirit lander weighed 120 kilograms, Beagle 2鈥檚 weighed 15 kilograms. 鈥淚t was clear to us from the start that they had not allocated enough mass to the design,鈥� says Spampinato.

Despite its reservations over the mass allocation, ILC Dover agreed to take on the project and began to build a system in which three airbags would inflate during descent. Each bag would consist of an inner bladder to contain the gas and two abrasion layers to protect the bladder from puncture. By contrast, the airbags for NASA鈥檚 rovers had six abrasion layers.

As the project progressed, ILC Dover鈥檚 concerns over the mass allocation grew, and its engineers asked for more 鈥� a request that was difficult to grant as the design had already been settled. 鈥淲e eventually got more mass but not as much as we hoped,鈥� says Spampinato.

And then the testing of the airbags went awry. When the ILC Dover team inflated the bags in a vacuum chamber, somehow the instruments used for measuring factors such as pressure had not been calibrated. 鈥淲e just got the wrong answer and that cost us time,鈥� admits Spampinato. Time was running out.

Back in the UK, things were about to get much worse. In mid-2001, Martin-Baker pulled out of the project entirely. Senior managers at the firm have refused to comment but others say that financial problems lay at the heart of the dispute. 鈥淢artin-Baker鈥檚 costs were escalating severely,鈥� says Mike Healy, the engineer at Astrium who had responsibility for the Beagle project in its later stages.

Martin-Baker鈥檚 withdrawal exposed some dire shortcomings in the way Beagle 2 was being managed. Suddenly the web of gentlemen鈥檚 agreements on which the project was built didn鈥檛 look so good: nobody knew what the other teams were doing. Without Martin-Baker there would be no landing system, and without a landing system no mission. 鈥淭he withdrawal was ill-timed for a programme that had an urgent due date,鈥� says Spampinato, with some understatement. Martin-Baker鈥檚 decision left the Beagle 2 team stunned and the project close to collapse.

An urgent decision was made to appoint a prime contractor with overall responsibility for Beagle 2, and Astrium agreed to take on the role. In a complex agreement, Astrium continued to work with ILC Dover and employed some of the Martin-Baker engineers who had worked on the lander. Crucially, several key engineers at Martin-Baker left the project. To make matters worse, communications between Astrium and Martin-Baker were poor. 鈥淭o put it mildly, we had trouble getting information out of Martin-Baker,鈥� says Richard Slade, an engineer at Astrium who worked on the landing system.

Then Astrium discovered that there was a severe shortcoming in the landing system. 鈥淚t soon became clear to us that the landing system wasn鈥檛 going to work,鈥� says Healy.

The first problem was that the airbags leaked badly. Although the bags鈥� internal bladders were made of airtight material, the gas was escaping through the seams. Spampinato believed that a small amount of leakage would not be a problem, as long as the bags were inflated at the last minute. On the Pathfinder mission, for example, the airbags were deployed when the vehicle was only a few metres above the surface, as measured by a radar altimeter. As far as ILC Dover was concerned, the bags had to remain inflated for only a short time.

But there was no altimeter on Beagle 2. Instead the plan was simply to inflate the bags early in the descent. 鈥淲e realised that if we deployed them too early they would deflate before we hit the ground, too late and they wouldn鈥檛 have time to inflate,鈥� says Slade. The only option was to fit an altimeter on Beagle 2.

Adding a new instrument to a spacecraft so late in its design is unusual. Engineers would have to find a place on the lander for the instrument and then change and test the spacecraft鈥檚 systems. They soon discovered, however, that the lander was full. To squeeze it in they would have to take a radical step.

Inside Beagle 2鈥檚 housing was a layer of foam and Kevlar cladding designed to protect the delicate innards during landing. To make room for the altimeter, the team decided to cut a hole in this layer. By the time the lander touched down, they reasoned, the altimeter would have done its job so it didn鈥檛 matter if it was smashed. It might even help absorb some of the impact. In December 2001, the altimeter was added to the spacecraft.

Then in early 2002, the airbags failed during routine tests. They were supposed to protect the spacecraft in impacts at up to 30 metres per second. But in tests at this speed, the bags burst. With about a year to go before launch, the pressure began to tell. 鈥淭here were times when we couldn鈥檛 see any way to fix these problems,鈥� says Slade.

Engineers at Astrium came up with a solution, but it required yet more changes to the spacecraft. They decided to reduce the impact velocity. Increasing the size of the existing parachute was out of the question, since the extra material wouldn鈥檛 fit into the space available. So with just months left, Astrium set to work on a parachute 50 per cent larger, made with a lightweight material consisting of nylon reinforced by Kevlar.

With the help of Lindstrand Balloons and Analyticon, a mathematical modelling company in Stevenage, UK, Astrium settled on a design called a ring sail that had been used by the Apollo missions. In an extraordinary feat of engineering, the team designed, tested and manufactured the new parachute in a matter of months. 鈥淲e did all the testing we needed and we were satisfied that it could do the job,鈥� says Stewart. The parachute was then tightly packed into the small space provided for it.

There was one final hurdle for the parachute, however. Before launch the entire spacecraft would have to be sterilised to ensure that it would not contaminate Mars with any life form from Earth. This involved blasting the parachute with gamma rays for 48 hours, a process that was guaranteed to destroy all carbon-based life forms it harboured. But what about the carbon-based parachute material itself? 鈥淲e were concerned,鈥� says Stewart, 鈥渂ut we exposed a test parachute to a similar dose and it showed no damage.鈥�

Question of space

Meanwhile Slade and his colleagues were battling with yet another airbag problem. The airbags had to be packed into a small space between the lander and the spacecraft鈥檚 outer shell, and in July 2002 it became obvious that no matter how tightly they were folded, they would not fit. Another strategy was needed.

The team began looking at how it could modify the spacecraft鈥檚 protective outer shell to give the airbags more room. The shell consisted of two halves: a front shield designed to absorb the heat of entry into the Martian atmosphere, and a rear shell to seal in the lander. The two were separated by a spacer.

To create more room for the airbags, the team designed a thicker spacer to increase the separation between the shells. This would give the engineers a few extra centimetres in which to pack the airbags, but it was by no means straightforward to build. The two halves of the shell contained explosive bolts to force them apart during the descent, and they were joined by a bioseal that kept the contents sterile after the gamma ray treatment. Despite this complexity, the team pulled off yet another extraordinary feat: the new spacer was designed, built and fitted in the nick of time.

Somehow, Astrium completed the lander in February 2003 ready for launch in June. But the problems had taken their toll. The total cost of the mission had risen to more than 拢40 million, although ESA, Astrium and the UK government had agreed to underwrite this amount. And Martin-Baker and Astrium are now in dispute over the extra costs associated with redesigning the landing system.

Mars Express blasted off on schedule, and released Beagle 2 on 19 December last year. However nothing more was heard from the lander. No one is even sure whether it successfully entered the Martian atmosphere.

The rash of last-minute changes raises the question of whether all the problems with the spacecraft had been resolved before launch. If some flaw remained, Beagle 2鈥檚 loss may have had little to do with the exotic conditions it encountered as it descended into the Martian atmosphere and everything to do with the curious way in which it was built.

But with the benefit of hindsight, most of Beagle鈥檚 problems can be traced to the way in which the programme was funded. Healy points out that final funding was not approved until June 2001, only 18 months before delivery. By comparison, he says, it takes at least two years to build a commercial satellite, longer if any development work is needed. 鈥淚 really believe it was a fantastic achievement to deliver the lander,鈥� says Healy. 鈥淏ut it was not a benchmark for how to run a programme.鈥�

The ESA inquiry is likely to agree and may go even further with its criticism. The Beagle team will not have long to wait to find out 鈥� the inquiry is due to report at the end of March.