A story for the science books and a legacy of success

The Roving Twins
Fifteen years ago we sent them forth, flying through solar wind. In November 2003 the sun hurled the largest flare ever recorded (now estimated to be X45), decisions were made, the craft were hibernated, and flew blind until the stream of particles subsided. Despite energies that could have fried them, they lived. Instructions were sent, the spacecraft became landers, knowing how and when to hurtle themselves through fire, eject heat shields, trigger parachutes, and land. Seven minutes after landing… they each told us… they were alive. Now, 15 years into an originally planned 90 day mission, the last one has just retired, but not without leaving behind an incredible wealth of data and invaluable information to be analysed over decades to come.

Sent on a nominal 90-day mission, their objectives were to find signs of water, to tell us if Mars ever had water on the surface. Spirit quickly suffered a problem (the Sol 18 anomaly) – which we were able to fix from the Earth. Opportunity, though, seemed to have a blessed mission. Opportunity landed in Eagle crater, surrounded with the evidence we were looking for. Mission engineers were not planning on Opportunity landing there, but as if guided, she ended up inside this small ‘dent’ on the surface of Mars. This small crater is ringed with fine sedimentary rocks, and hematite nodules – and with that, we had the proof that this area of Mars was once the site of an acidic and salty sea. Mars had once had persistent water.

The roving twins lived through file-systems problems, bit-rot, bugs – fixed on Mars, our own learning curves, and achieved the nigh impossible. In May 2011, Spirit ceased to answer, parked at a bad angle, she didn’t catch enough sun to recharge. After seven years, she fell silent, leaving her sister to roam the red planet alone.

And… roam… Opportunity did. More than seven more years. Now, hope is lost.

She provided us with countless findings, gigabytes of science, reams of photos, and prompted another evolution of our science books. The red planet continued to test and tease the remaining twin rover, finally obscuring the sun with dust. In the dimness of red skies, she was commanded to sleep, perchance to awaken and live another day.

The remarkable thing is both of these robots made it to Mars. They made it intact, healthy, and did exactly what they were programmed to do. Before 1997, over 70% of attempts to reach Mars failed. Since then, most of NASA’s missions to Mars have not only succeeded, but exceeded life and mission goals. What changed?

COTS Allowed
With Mars Pathfinder (originally MESUR Pathfinder), NASA directed that unmanned probes should be made using commercially provided parts (COTS – Commercial-Off-The-Shelf). By using commercially made hardware and software, NASA Engineering teams were able to leverage mature systems and concentrate on building their spacecraft.  NASA-JPL chose Wind River’s VxWorks as the operating system running on that first COTS mission.  Many more followed and now 7 of these are still operating. The last success in this series is InSight…still roaming, or rather, drilling on Mars.

Courtesy of Wind River.