A flying Terran unit in Starcraft. It is a sphere surrounded by a ring with three more spheres on it.
Ground attack: no
Air attack: no
Sight range: 10, detects invisible
Build time: 80
The Science Vessel has several of the most useful abilities in the game against Zerg and Protoss. Out-of-the-box, it has Defensive Matrix, and it is a detector of cloaked or burrowed units.
The Defensive Matrix costs 100 energy. It puts a very strong shield around any other unit, preventing almost all damage to it, up to a limit of 250 hit points protection or 30 seconds elapsed time. One should generally defensive matrix a unit which is about to go into heavy fire. Best uses:
- helping a dropship last long enough to deliver all of its cargo
- protect a nuke-guiding Ghost
- relieve the target of a Scourge attack
- when attempting to break up a siege tank blockade (either with a ghost and lockdown or with a siege tank or two of your own)
- if running a siege tank blockade or tank push of your own, you may use a Defensive Matrix to keep 'friendly' splash damage from ruining the day of any units which end up closely engaged.
- saving a beleaguered battlecruiser
Using Defensive Matrix on a unit already affected by Defensive Matrix simply resets the damage and time counters -- the shields do not stack.
Try to use defensive matrix on units before their health gets down into the single digits. Half of the time, 1 damage per attack leaks through the shield -- and if they are that damaged, those 1 damage can add up to finishing your unit off while the shield still has a lot of juice left. Also unfortunately, the Science Vessel cannot target itself with Defensive Matrix. Defensive Matrix does not protect against the Queen's Spawn Broodling attack. Though Defensive Matrix does protect against Irradiate and Psionic Storm, they deal damage multiple times and can leak considerably. Irradiate in particular is troublesome, as it deals 75 packets of 4 damage each, for an average of 37.5 leaked damage.
Irradiate can be researched for 200 minerals and 200 gas. It costs only 75 energy (cheap!), and does 250 damage over 30 seconds to all biological units within 2 squares of the affected unit. Note that the Biological units are: all Zerg, all Barracks units, SCVs, Zealots, and both high and dark Templar. Since nearby units are no less affected than the target itself, whole stacks of mutalisks or overlords can be wiped out if the victim's player does not spread them out. Alternately, one can irradiate one's own siege tank if it is rushed by wounded zerglings. Overlord, Mutalisk, and Queen hunting are my principal uses for Irradiate -- with full energy, you can kill 3 units (stacks, if you're lucky) per run. At that rate, a single run easily recoups the cost of the science vessel. Note that the Irradiate condition can be removed by Medics' Restoration ability.
Irradiate cannot target burrowed units. If an already affected unit burrows, the radius effect is suspended; similarly, a burrowed unit is unaffected by the radius effect of others. If the affected unit goes inside a transport or bunker, it affects the units inside instead. An overlord containing an affected unit is, peculiarly, not affected.
If not fighting Zerg, Irradiate is infrequently worth the cost. It can be worthwhile against hordes of High Templar, because the science vessel is maneuverable enough not to be caught for long in any but the most intense of psi storms. Even if you are fighting Zerg, and if the opponent goes with mainly ground units, irradiate is not very worthwhile until very late in the game, if a standoff is reached. If there are no crystals left, it's excellent for picking off units with little chance for retaliation.
Electro - Magnetic Pulse (EMP) can be researched for 200 minerals and 200 gas. It costs 100 energy, and wipes out all Protoss shields and all 'spell' energy of units and buildings within 3 squares of the target (which can be empty ground), excepting only the spell energy of the Science Vessel which launched the EMP. Having its shields (and spell energy) stripped away will give any Protoss force second thoughts about advancing, especially if it relies on Archons (dark or light) or High Templar. Clusters of spellcasters are prime choices. Other nice targets are Shield batteries, or protoss buildings which are about to be nuked (instead of being severely damaged, they will be destroyed). As a side-effect, this dispells Hallucinated units, and kills broodlings.
Against non-Protoss, I would only get EMP if you suspect your opponent will be playing with lots of spellcasters you can't Irradiate. The main two examples of this are a horde of Battlecruisers and a horde of marines supported by Medics. Both make tasty EMP targets.
There is also an Energy Capacity upgrade from 200 to 250, which costs 150 minerals and 150 gas. If hunting Zerg, this is well worth it as it raises the number of Irradiates per hunting run from 2 to 3. Otherwise, it is not quite as useful.
Strategies with alien allies
In a Terran/Zerg alliance:
Use defensive matrices on Infested Terrans to improve their success rate to nearly 100% (note, your Zerg ally can infest friendly command centers, so you can always make Infested Terrans if you think this capability is worth 400 minerals). Oh, and if you're attacking Protoss buildings larger than a photon cannon, EMP before blowing the Terran (just like when you nuke them).
In Broodwar, another good target for a defensive matrix is the Lurker - it may otherwise have some trouble getting into position. This is analogous to the use of a defensive matrix on a siege tank while it's moving in on another siege tank formation, but useful on different targets.
Against Protoss, use a Defiler's Explosive Plague to soften them up. This will do up to 300 damage to the structure under their shields (but won't destroy them). Let the plague run its course. Repeat as necessary to wear down Carriers or large buildings. Later, when you're ready to wipe them out, you can follow up with an EMP. This will leave them with 1 HP. The beautiful thing is, it doesn't matter how much later! They can't repair, after all... The only exceptions are if the Protoss has access to Terran Medics (via an ally or Mind Control), and that only helps the biological units.
Against Terrans, if their SCVs are within range of their siege tank defense, Defensive Matrix a queen so it can zoom into their base to use Spawn Broodling on an SCV. The siege tanks will then fire on the broodlings among the miners, probably killing several additional SCV's. While this can be done without a Defensive Matrix, it is much more likely to succeed, and far far more likely to result in a living queen.
In a Terran/Protoss alliance (or if a Protoss has gained a science vessel through mind control):
One attack strategy is to fly an Arbiter over the enemy base and then recall in your troops. This is kind of suicidal. Usually, illusions are used to defend the arbiter. You can supplement that with a defensive matrix. Just stack the three on top of each other so the opponent can't tell which is the illusion; and even if they figure out, the building-based air defenses are a pain to direct (single selection only). You cannot shield hallucinations.
Aside from that, the one case where a shield makes the most difference is on Dark Archons, just before Mind Control. Also, High Templar can Psychic Storm away enemy Siege Tanks much more easily if they can survive long enough to get in range. Carriers, Arbiters, and Reavers have giant target signs on them; defensive matrix takes that sign down. Also, a defensive matrix remedies Shuttles' low health issues (though this is not really novel, it does make a bigger difference than with the dropships).
If you are Zerg and you are facing science vessels, your principal counter is defilers + mutalisks, or scourge. Mutalisks alone are too slow - the vessels can retreat and repair. Two scourge per science vessel will do the trick, if they can both get through. Science vessels are not slow; you may need to ensnare the science vessel with a queen. This of course carries its own risks (your queen could be irradiated).
If you are Protoss and you are facing science vessels, your principal counter is Scouts, since they are generally powerful, can't be directly killed by the vessel, and can run away if EMPed. They might even be worth using Mind Control on (you might as well... if a science vessel is around, your Dark Archon will probably lack shields and spell energy in a moment anyway). Barring that, use Feedback.
If you are Terran and you are facing science vessels, you don't have too much to worry about. You probably are using an armored army or medics, so Irradiate isn't effective. If they come to EMP your Battlecruisers, Yamato them. They'll get the EMP off, but the Yamato that got started will go off and nail the science vessel. So your biggest worry will be defensive matrices. There's not much you can do about that except prepare a defense in depth against dropship attacks.
Statistics taken from Starcraft Strategy Central at Battle.net; interpretive text is all original
There is no clear single descendant of this vessel in Starcraft 2.