Nasa's Interstellar Boundary Explorer (Ibex) spacecraft has been launched into Earth orbit to study the edge of our Solar System.
Ibex was launched on Sunday aboard a Pegasus rocket that was dropped from a jet flying over the Pacific Ocean.
It is the first probe to study particle interactions at the boundary where our Solar System meets interstellar space.
The two-year mission should shed light on the decline of the solar wind, which is at its lowest pressure in 50 years.
The interstellar boundary is the point in space at which the particles emitted from the Sun begin to compete with those from elsewhere in the galaxy.
This region serves as a buffer that protects the Solar System's interior from 90% of the cosmic rays heading towards it.