Defending your worlds: Radar, Aegis, ground guns, posture and recovery

Defence is about the attacker’s maths

Nobody in Astera can wipe you out, and you cannot make a planet impossible to raid. What you can do is make raiding you a bad decision. An attacker who probes you compares three things: the loot range, the defence they must beat, and the losses that defence will cost them. Shrink the first, raise the second and the third rises with it. A commander whose probe report shows a small pile of resources behind a mixed defence and a full Aegis will usually look for someone else.

Remember also how Dominion works. In a scored battle, the defender receives the opposite of the attacker’s result. If a raid on you loses more ships than it carries away, you gain Dominion without leaving home. Good defence is not only damage control; it scores.

The layers of a planet’s defence

Every planet defends itself in layers, and each one answers a different part of the attacker’s plan:

• Radar warns you, with an arrival time from level 1 and more detail at higher levels. It buys time.
• Aegis absorbs damage before any unit is hit. It buys rounds.
• Ground defences fight every battle, cannot be lured away and are partly rebuilt for free afterwards.
• Your home fleet adds firepower and the right classes, but only while it is home.
• The Store protects a fixed slice of each resource, and what you spent cannot be stolen at all.

No single layer holds alone. Aegis without combat-ready units cannot hold a planet. Ground defences without Aegis take the first hits directly. A fleet away on a mission defends nothing. The layers work because the attacker has to beat all of them in the same battle.

Aegis: the shield that refills itself

An active Aegis takes combat damage before ships and ground defences. Its maximum strength grows with level, and it regenerates 35% of that maximum every hour at no cost. After a battle drains it, recharge starts 15 minutes later.

Aegis also protects against radiation: each active level reduces radiation damage to ships on its planet by 1 HP per minute, as long as it has shield left. Two weapons are built to break it. Nullifiers strike Aegis five times harder at the opening of every round, and a Death Star’s EMP drops it to zero and stops it refilling for an hour. A probe report showing Nullifiers in a rival’s fleet is a sign of what they plan to hit.

Ground guns and the Core’s ground capacity

Ground defences use the Command Core’s ground capacity rather than Hangar room: 30 at Core 1 and 10 more with each level, so 50 at Core 3 and 120 at Core 10. A Thorn uses 6, a Harpoon 10 and a Bastion 18. At Core 10 you could field, for example, six Harpoons and three Bastions in 114 of your 120 capacity, a mixed Lance and Bulwark wall that punishes both Skirmisher-heavy and Lance-heavy attackers.

Ground guns cannot fly, transfer or retreat, and they have no personal shield. In exchange, 60% of each destroyed type is rebuilt free after every battle, rounded down, and Emplacement Doctrine research raises their attack and hull strength on every planet you own. They are the cheapest way to make a planet expensive.

What to do during a Radar countdown

A Radar warning is the most valuable number in defence: the minutes you have before impact. Use them deliberately:

• Spend the Store. Queue an upgrade or a ship order; what is spent cannot be looted.
• Decide on the Works. Collecting moves resources into a larger exposed share, so collect only what you are about to spend.
• Bring ships home if they can arrive before the attack, or send away ships that would only die.
• Finish or move repairs. Ships in the workshop do not fight, and the Radar countdown tells you whether a repair finishes in time.
• Check your posture. If the attack is overwhelming, tactical retreat may save the fleet; if clanmates can help, support may hold the planet.

At Radar level 4 you also see an estimate of the attack’s strength, and at level 5 its origin and ships. Both change which of these actions is right, which is why the Radar is usually the first instrument worth raising on a contested world.

Hold, retreat or call for support

Each planet has a defence posture. Hold means the home fleet fights. Tactical retreat lets the fleet leave automatically before a hopeless battle: it needs at least five armed ships, enough deuterium and an attacker at least three times stronger than the defending line, counting classes, research, wounds and Aegis. If those conditions fail, the fleet fights. Ground defences always stay, and unprotected resources can still be taken.

Clan support is the third option. When a planet accepts support, clanmates can station their ships there; they stay theirs, fight alongside your own with their own research, and can be recalled. With support alone the planet never retreats; with tactical retreat on too, a raid that outmatches the whole line, host and support together, lifts everyone at once, and the host’s deuterium pays only for the host’s ships. Support turns a lone defence into a shared one, at the price of putting allied ships at risk. Defence posture and clan defence support give the full rules.

After a heavy loss: recovery protection

Astera includes a safety net so that one bad night does not end your season. If your net losses over a recent window pass a threshold, measured in hours of your own production, all your worlds receive a 12-hour recovery shield. For commanders in tiers 1–3 the threshold is two hours of production lost within eight hours; from tier 4 it is four hours within six. The world that was struck also produces 50% more while its recovery boost lasts.

Two details are easy to miss. Profit from your own player raids is deducted from the losses, and launching a hostile attack on a player prevents the shield from being granted. If you are hit hard, the best response is often to rebuild under the shield rather than to strike back at once.

Strategic weapons: Death Stars and interceptors

Later in a season, Death Stars appear. A Death Star is a single-use EMP weapon that needs a local Core 13 and Shipyard 5 and costs 50,000 alloy, 35,000 crystal and 3,000 deuterium. A hit drops Aegis to zero for an hour and takes ground defences out of every fight in that hour; ships at home still fight. On a colony, each hit also takes 20 loyalty and can break a fault, and five hits in a row on a full-loyalty colony turn it neutral.

The answer is interceptor charges. Each charge stops one Death Star or radiation bomb automatically. A planet holds two by default; the Interception Grid research raises that to four and then six. Building charges needs an Uplink and a Radar at level 3 on that planet. Count ready charges, not capacity: a charge still under construction stops nothing, and several weapons arriving together can exceed what is ready.

Defence checklist

• Radar first on any world that matters; aim for level 4 to see strength.
• An active Aegis, raised with the Core.
• A mixed ground wall that fills the Core’s ground capacity.
• A home fleet of mixed classes, not your entire navy away at once.
• The Store spent down before every absence.
• A posture chosen in advance: retreat for a weaker fleet, support if your clan is active.
• Interceptor charges ready before Death Stars appear in your galaxy.

A well-defended planet is not one that never gets attacked. It is one that makes every attacker pay more than they take.