Rocket Lab's first Electron rocket launches from New Zealand on May 25, 2017.

Update, 1:38 a.m. EDT on May 4: Rocket Lab has called off Saturday's launch attempt to perform additional payload checks. The launch is now targeted for Sunday (May 5) at 2 a.m. EDT (0600 GMT).

Spaceflight startup Rocket Lab will launch three small satellites for the United States Air Force early Saturday morning (May 4), and you can watch the action live.

An Electron rocket is scheduled to lift off from Rocket Lab's New Zealand launch site Saturday at 2 a.m. EDT (0600 GMT; 6 p.m. local New Zealand time), kicking off the STP-27RD mission. Watch it live here at Space.com courtesy of Rocket Lab, or directly via the company .

STP-27RD will loft three research-and-development payloads for the Air Force's Space Test Program (which explains the mission's name).

Related: In Photos: Rocket Lab and Its Electron Booster

The Space Plug and Play Architecture Research Cubesat-1 (SPARC-1) will advance the development of miniature avionics, among other gear. The Falcon Orbital Debris Experiment (Falcon ODE), also a cubesat, will help researchers evaluate how effectively space junk can be tracked from the ground. And the larger Harbinger craft aims to demonstrate that a commercially built satellite can meet certain U.S. Department of Defense requirements, Rocket Lab representatives have said.

Together, the three satellites weigh more than 397 lbs. (180 kilograms), the heaviest load for the 57-foot-tall (17 meters) Electron to date.

Tomorrow morning's launch will be the sixth overall for Electron, and its second flight of 2019. The two-stage rocket last flew in late March, when it lofted the experimental R3D2 satellite for the U.S. Defense Advanced Research Projects Agency (DARPA).

Rocket Lab aims to dramatically increase access to space using Electron, which can loft about 500 lbs. (225 kg) on each $5 million liftoff. There will be no rocket landing tomorrow: Electron is an expendable vehicle.