Priority: Mars

"Admiral Hackett ordered the Normandy to Mars to locate new Prothean data that could help defeat the Reapers, but the archives on Mars are not responding. Investigate the digsite and find the Prothean data."

The Reapers have come. Shepard has been ordered to go to the Citadel by Admiral Udina, however as soon as Shepard leaves Earth he receives a message from Admiral Hackett informing him of a secret on Mars. Shepard heads there first.