Experts from across the world are meeting at the European Space Agency's European Space and Technology Research Centre to discuss how to best calculate spacecraft orbits. Even though the space age is now 49 years old, determining the optimal trajectories for spacecraft remains a far from easy task.
Space missions, even to relatively near planetary bodies, are constrained by certain factors such as the thrust used to launch the spacecraft, the target object, and the time required to reach that destination. Even when they work out the best trajectories within such constraints, engineers tend to produce different strategies.
"Ask ten engineers for the best orbit for a particular spacecraft and you'll get ten different ideas," said Dario Izzo, an ESA researcher and member of the agency's Advanced Concepts Team. Each proposed trajectory could be the best for a certain reason, he explained, so the question becomes: Which one is truly the best? One of the proposed trajectories or another that remains unknown?
Izzo said his team has been developing an approach called global optimization. It is a method of handling complex problems that present many variables. To compare and contrast those variables, the Advanced Concepts Team recently launched a competition. They issued a challenge to space engineers across the world to find an intercept trajectory that delivered as much energy as possible to asteroid 2001 TW229.
Twelve teams, from the United States, China, Russia and Europe each submitted their respective best solution. Izzo ranked the proposals according to how much energy each mission could impart to the asteroid.
"The inspiration for this competition was asteroid deflection, a problem we have been working on quite thoroughly," he said. Asteroid 2001 TW229 presents no danger to Earth, but the trajectories simulated a step that would have to be taken if astronomers did discover a potentially dangerous asteroid. The key to the mission would be to deliver the largest push possible, in time for it to do the most good.
The top ranked trajectory went to a team from NASA's Jet Propulsion Laboratory in Pasadena, Calif. (closely followed by two Spanish teams). The winning orbit involved seven planetary flybys, mostly of Earth, but also included Venus, Jupiter and Saturn. In the end, the track would smash the imaginary spacecraft head-on into the asteroid.
All the teams are meetings in the Netherlands to discuss their individual approaches to the problem. "The response to the competition was excellent. At the meeting we will discuss the different methods used, and identify the ones that have proven the most promising," Izzo said.
He added that the Advanced Concepts Team also hopes to run future competitions to stimulate further research.
