Complex sentence: Piccard initiated the Solar Impulse project in 2003, but since then the team has grown to a multi-disciplinary team of 50 specialists from six countries, assisted by about 100 outside advisers.
Split into simpler sentences: Piccard initiated the Solar Impulse project in 2003. Since then, the team has grown to a multi-disciplinary team of 50 specialists from six countries, assisted by about 100 outside advisers.