A vehicle now in use on Rannoch.
Mobile Defense Drone
Making war is, fundamentally, a losing proposition for the quarian species. The outcome of the Evening War put this concern into full relief - a little over half of the quarian population annihilated, and countless victims of a fruitless ground war for the homeworld. To command the quarian military, one had to understand the inherent limitations that the quarian people had to face in military matters. Wounds would snowball quickly. Near-misses became crippling infections. Casualties rose to fatalities. Fatalities were, well, wholly unacceptable. Now of all times.
And yet conceding this was equally unacceptable. Leaving their defense to the geth would be wholly counterproductive - and as a matter of political course, would speak poorly of the newfound equality between the two races. The quarian people were not helpless, and limited that they might have been, limitation bred innovation. So the mantra went, anyways. A new quarian military doctrine had to be built - with new tools and new means. An acceptance of the quarian weakness and the ingenuity to develop around that single truth.
Chief among these concerns concerned the simple matter of extending combat endurance among quarian ground forces. Hits meant something else entirely for quarians than any other species, after all. The solution was simple: don't get hit. A philosophy drilled firmly into the minds of the engineers at Special Projects Lab 17. Teams were encouraged to prototype and test their own solutions. Develop mechanical solutions to biological limitations. From this, the Zahra was developed.
Although, in truth, the Zahra was really just the consolidation of two separate ideas - the Xfn-0 Satu and the Xin-0 Caana - projects headed by two individual Lab 17 teams. Satu's designers took inspiration from naval combat - an area of strategy that the quarians could at least take unreserved pride in. They reasoned that, much like how the quarians dealt with war, victory or loss was decided by the first real blow. Victory precipitated on whoever could fend off that blow first. To address the endless swarms of fighter-bombers that swarmed the vast kilometers a space engagement stretched, GARDIAN point defense was developed to stretch out operational endurance.
Satu's design team applied the logic to a ground-based conflict in a somewhat straightforward fashion. Essentially a miniaturized GARDIAN battery on a hover trolley, Satu's most distinctive feature was the fairly advanced target identification virtual intelligence suite and spherical camera installed atop it. Designed to automatically and instantly track, identify, and neutralize incoming munitions - namely missiles or other such explosives.
Caana's designers borrowed from the same root of inspiration in naval combat - only they took it in a somewhat different direction. When all of a ship's more advanced defense systems failed it, at the end of the day, it's greatest survivability asset was in its' shields. Thus their concern became firmly vested in extending kinetic barrier endurance. Thus was the Caana built, a heavy drone built to project a kinetic barrier about four meters in radius around it, capable of resisting up to 15 seconds of sustained light mass accelerator fire. The drone intelligence itself was somewhat rudimentary, designed to follow a tagged IFF and activate when either manually initiated or when the VI recognized that emergency intervention was necessary. Fine-tuning the sensitivity of that window was the product of much of the Caana team's grievances.
Given the similarities in foundation with these two concepts, it was only natural for them to merge. After the initial project evaluation, the heads of both projects saw value in pooling their ideas together. Hence the Xdn-0 Zahra was born. Built off the Caana's frame and fitted with a somewhat oversized reactor, the Zahra found simple synergy in the two concepts - the Caana's projected barrier folded pitifully against the concussive force that a grenade could apply and the barrier allowed the Satu's laser to pass through harmlessly. It brought the logic and security of a naval engagement into a single drone platform. Indeed, the Zahra itself resembled a ship in miniature.
Sadly, a jack of all trades is a master of none, and in a strict performance sense, while the Satu's laser could fire and cycle once over five seconds, the Zahra could cycle at 8.5 seconds. The would-be space for heatsinks and radiators were largely displaced by the shield generator, and so the drone's venting capabilities gained a fat few seconds. While the Zahra's designers sought to mitigate this with Diffuse Radiation Arrays, even the best efforts couldn't solve the drone's markedly lesser heat endurance. And to reduce strain on the drone's reactor that firing the GARDIAN, the Zahra's shield generator projected a barrier one and a half meters smaller in radius than the Caana's - its' rated endurance slashed to nine seconds against fifteen.
Of course, the largest issue in the Zahra's design was simply that it lacked enough power to do everything it aimed to do at once, even equipped with its' large reactor. Deflecting incoming rounds and firing lasers would serve to quickly deplete the Zahra's energy reserves - leaving an operational window of just eight active minutes. A tremendous issue to be certain, though the Zahra impressed quarian military officials nonetheless, attracted by the naval sensibilities. Xdn-0 became Vdn-0, and the Zahra was commissioned for 'live field testing' among the Army of Rannoch-in-training.
The Zahra itself received mixed response among many quarian soldiers - the drone's limitations inherently left it poorly equipped for the initial phases of an engagement, and its' size made it hard to transport quickly. While the advanced point defense suite and the shield emitter was appreciated, the Zahra gained a reputation more as a 'bailbot' or 'FUBAR button' than anything else, used to bandage bad situations rather than actively support a firefight.
The laser that the Satu uses is built off of discoveries made by Special Project's wartime investigative disassembles of captured geth Hopper platforms and their integrated laser projector. Such details are kept close to Special Projects' chest; though it's more or less an open secret.
A few Zahra are in use with quarian reclamation teams, using the drone's laser to neutralize undetonated explosives and the shield offering some measure of guarantee in unstable areas.