This mission can only be obtained after completing Priority: Mars.
Go to the Citadel Embassies and head left, where you will find a volus speaking to a human and a turian on the far corner of the area. Listen to their conversation about a Prothean obelisk in order to acquire the mission. You can also acquire it if you scan the target planet first.
Walkthrough EditUrla Rast system of The Shrike Abyssal. Scan the planet Talis Fia and recover the artifact with a probe.
Return the artifact to the volus to be rewarded with 5 Reputation and 20,000 credits.
Note: This mission can only be completed after completing Priority: Palaven, which is when the star system will open for travel.