If all goes well, NASA will finally launch its Magnetospheric Multiscale (MMS) observatories tonight. Comprised of four identical spacecraft (shown above in a clean room), its purpose is to study the magnetic fields around Earth for information on how they connect and disconnect. The MMS is headed to areas that scientists believe are the sites where magnetic reconnection occurs, but first it has to get off the ground. The launch is scheduled for 10:44PM ET at Cape Canaveral Air Force Station, and all conditions are go. You can watch live on NASA TV, and a stream is embedded after the break.
Update: The launch was successful and the mission is on its way, check after the break for a replay and to see more information on exactly what its satellites will be studying.