Railjack
This page explains what you can do in Railjack missions.
A Railjack is a Spaceship. During a mission, you will be fighting enemy ships and try to complete your mission. Defeating enemies can give you new blueprints for your ship. There are Intrinsics, which are like skills and the higher rank a class is, the more abilities you’ll unlock.
Orphix
Requierment
Upon entering a ship, you need to get rid of the Sentient Orphix. The Orphis generates a bubble, which forces you to go to Operator mode. You may not be able to get in with your Warframe but you can get in with a Necramech.
Destroy Resonators, that look like red crystals to make the Orphix vulnerable. Shoot at the Orphixes core. When you deplete half of its health, it will spawn resonators again. Destroy them and try not to get destroyed by the Sentients. When you destroy all resonators, you can destroy the Orphix. Destroy 3 Orphixes to finish the mission.
Orphix resonator
Sentient Orphix
Sentient Anomaly
Sentient Anomalies only appear in nodes, that have a blinking sentient symbol, in Veil Proxima. When you finish your main objective, you get back to your Railjack and approach the anomaly, which is a big sentient ship. Exit your Railjack, enter the anomaly and complete the task, which is killing sentients. Finishing the task will grant you one anomaly shard.
Example of a node that has an anomaly in it