The Mars programmes for NASA and the European Space Agency are going to merge, following a bilateral meeting between the agencies in Plymouth, England last week. [BBC]

The agencies’ two science chiefs, NASA’s Ed Weiler and ESA’s David Southwood, have been talking about the need for this for months. Now they apparently have nailed something down, though the agencies are being deliberately vague on exactly what was agreed to — they don’t want to spoil the agreement while Southwood rounds up approvals from ESA’s member states. “When we started out, David and I were the only ones that thought this could happen,” Weiler told a group of planetary scientists at NASA headquarters today. “David called it the most successful ESA and NASA bilateral he has ever seen.”

Joint missions happen all the time. What’s novel here would be a joint programme. That, says Weiler, offers the flexibility to trade commitments over the course of multiple years. In particular, the agencies are trying to hash out Mars mission planning for launch opportunities in 2016, 2018 and 2020. ESA has ExoMars; NASA wants to send a trace-gas detecting orbiter. One likely scenario is just a big joint mission in 2018. The 2016 launch date for ExoMars was a poor one for orbital mechanics and martian weather, and by sharing the same launch rocket in 2018, money would be saved.

Image: ESA