A space probe crashes in the desert. Something deadly on board wipes out almost the entire population of a small town. The government instigates an emergency protocol and top scientists gather at a secret underground quarantine facility to contain this killer germ from outer space.
Will they be able to save the planet from disaster?
To find out, read Michael Crichton’s Andromeda Strain – an adventure with heroic scientists. This terrifying tale of alien microbes, bringing instantaneous death to (almost) every living creature they come into contact with, was published weeks before the first Apollo lunar landing. But Nasa had already predicted this worst-case scenario of bringing back material from another world.
On their return to Earth, the Apollo 11 astronauts were locked away in a converted Airstream caravan - the Mobile Quarantine Facility. Lunar rocks and soil were sealed in bags and only opened in airtight laboratories. Even the Apollo capsule was wiped with bleach to destroy any stray Moon bugs. In retrospect, these precautions look rather quaint and the whole rigmarole was abandoned after Apollo 14, when scientists concluded that the Moon was completely devoid of life.
But now, 40 years on, Nasa is dusting down those quarantine procedures for a new challenge: returning rocks from Mars.
A so-called Mars sample return mission is the next step in the exploration of the red planet, coming between the existing rover missions, such as Curiosity, and future human exploration. It may also, finally, answer one of the biggest questions about Mars: is there life?
“The Curiosity rover does not have the instruments to answer the ‘are we alone’ question by itself,” says David Beaty, chief scientist for Nasa’s Mars Exploration Directorate at the Jet Propulsion Laboratory in Pasadena, California. “All it can do is understand the environment. Testing for ‘is there evidence of life?’ requires another mission and the best way to do that is by collecting samples and returning them to Earth.”
Popping out for coffee
The reason scientists favour a sample return mission is that they do not know exactly what they are looking for. Martian life could come in many different guises and using equipment designed to detect life on Earth, may not pick it up on Mars. Nasa could design another rover, equipped with all sorts of life-hunting instrumentation, only to find it is taking the wrong measurements with the wrong detectors.
“If you have the wrong experiment on your rover, you can’t modify that,” says Beaty’s Mars programme colleague, Deborah Bass. “If you bring samples back, you have all the power of Earth’s laboratories at your disposal.”
But it won’t be easy. Although robotic sample return missions have been attempted before, they have had varying degrees of success. The first, Luna 16, landed on the Moon in 1970 and brought the Soviet Union back its own lunar rocks. In 2004, Nasa’s Genesis mission returned to Earth after capturing particles blown from the Sun. Unfortunately, the spacecraft’s parachutes failed to open and it smashed into the Utah desert spilling its contents. Nasa had more luck in 2006 with its Stardust mission to a comet but things did not go so well for the 2010 Japanese Hayabusa mission, which returned to Earth after landing on an asteroid. It only managed to capture a few dust particles, as projectiles designed to blast fragments from the surface failed to fire. No mission has yet returned samples from another planet.
Still, the good news is that they do not need to collect much. Whereas Apollo brought back several hundred kilos of rocks, soil and dust, Beaty reckons he would be happy with 20 Mars samples of some 15g to 20g each – between 300g and 400 g in total. Or, to put it another way, “what would fit in a coffee cup”.