Into the Abyss
Complete the Orrery Lost Sector on Nessus, and loot the Lost Sector chest.
Your Ghost's scans detect a source of Void energy on Nessus. And though you can't make out any words, you do hear whispers from the depths of the Orrery. Investigate, and bring anything you find back to Ikora.
Void hungers, does it not? It yearns for the antithesis of its own profound desolation.