Artifacts to obtain:
- random (wrecks //).
- seize the Excavation Site;
- destroy turrets along your path to the enemy base;
- get Rachel to the enemy base;
- hold positions by the base, until Rachel examines it and sets explosives;
- extract Rachel outside of the blast area.
Stat by obtaining resources to the East.
First of all, send LAVs and Salvagers to the East to search for resources . Send the remaining ones, and Kapisi towards the southern part of the enemy HQ . In the meantime, have Baserunner deploy scanners, so that you have view of the Eastern and Western part of the HQ, because the Carrier will go no further from this point of the enemy base.
Inside , you can encounter enemy resistance. Start a bomber attack on the production vehicle to the East  and finish off LAVs from point . Then, return to Salvagers near Kapisi and obtain more resources there (in wreck  or , there is a random artifact).
Now, you can produce units - mainly AAVs, RGs and aircraft. Also, you will make use of 2-3 Missile Battery. deploy Carrier in the first line of the defense to the North (transfer many points into Turret Network). The enemy will attack you from the North only, through the points shown in the above screenshot (two passages through the wreck).
EMP has a long range. Later on, also other units will be able to use it.
Time to strike back. First, use Rachel's vehicle to deactivate the building that controls the nearby turrets (Turret Control Tower), using EMP. Destroying it will result in deactivating the closest turrets. After you do that, move defense units to the Western passage  - this is the only point that the enemy units will arrive from. Inside the wreck , there is an artifact.
You can easily destroy the control tower from behind rocks, using Railguns.
Attack now from the Eastern part of the enemy base. You do not have to worry about any countering measures. Destroy the first control tower  with RGs, the second one , behind the hill - with Strike Fighters. Also, use Strike Fighters to destroy the towers by the Western passage , .
Hint: Use Strike Fighters to destroy turret control towers. It would take the bomber too long to get there and it would probably end up being destroyed (and you cannot produce these units, for now).
As Rachel make it over to the Gaalsien outpost.
With the turrets destroyed, you can launch the final attack. It is best to attack  from both sides. There are many RGs there and it is a good idea to destroy them with bombers. As soon as you have secured the area, go there as Rachel.
Hint: You can expect more enemy air-raids during the attack. For this reason, keep 1-2 Missile Battery in the base, command the other 1-2 with the Eastern army. Enemy jets will be arriving from the West only.
Hint 2: Before you reach your destination as Rachel, make sure that you have enough units to defend that point later on (mainly AAVs and RGs, you could also use some LAVs).
You can repair the enemy vehicle to seize it - it is the Honorguard Cruiser, a bit "cranked up".
You have to defend your positions up until Rachel finishes exploring the enemy base. This will take around 2 minutes. In the meantime, you will run into a Gaalsien Cruiser that you can fix to own it - it has strong attack and defense and you can make use of it later into the game.
You have to get Rachel safely outside of the blast area within alloted time.
After Rachel leaves the building, you will have to escort her outside of the marked area within 3 minutes. In the meantime, the enemy will launch an attack from both sides. Which way you go depends on the composition of your army. If you have many units and ranged AAVs, you can fight the enemy back on the Western side (armored units). If your army is dispersed and you have LAVs, head east (ranged units). Remember to use aircraft to your advantage. As soon as Rachel evacuates, this mission will end.