How Proton's launch pad works
All four existing launch pads for the Proton rocket at Site 81 and Site 200 in Baikonur feature similar design. The rail transporter with the assembled but unfueled rocket in horizontal position rolls in with its front chassis on top of a stationary hydraulic erector designated 8U260 of the launch pad. The device then rotates its arm 90 degrees and installs the rocket together with its railway transporter and its front chassis vertically onto the launch platform. The rear chassis of the transporter remains on the railway.
A scale model demonstrating a unique design of Proton's launch pad.
Launch pad operations
After Proton is installed securely one six supports of the launch pad, the transporter's fixtures holding the rocket are retracted and the erector rotates back into its storage position below the pad level, simultaneously lowering the transporter back on the rail tracks. The transporter than towed away by a locomotive.
Next, the 60-meter-tall service tower moves into position on its own rail tracks completely enveloping the rocket with its foldable access bridges. The launch personnel can then climb to various levels of the rocket during five days of a typical pre-launch processing. The service tower rolls away to a distance of about 340 meters from the rocket around 5-6 hours before launch.
Remarkably, six exhaust deflectors below the launch pad of the Proton rocket are only eight meters deep, or five times shallower than the collosal flame trench of the original launch pad for considerably smaller Soyuz rockets. Each of six channels below Proton's pad deflect exhaust from one of six engines on the first stage of the vehicle.
A cutaway view of Proton's launch pad in Baikonur.
All electric umbilicals are connected to Proton at the time of the launch through a special movable plate at the bottom of the rocket. During the first second of the liftoff, this plate trails the moving rocket and then separates and lowers itself into a special niche in the launch pad. A protective cover immediately closes over the niche.
Six retractable supports holding the rocket around its base are resting on the concrete foundation of the launch pad. Along with their job of fixing the rocket in place until the moment of liftoff, these supports also provide interface for propellant lines. The retraction of supports into special niches during the liftoff is carefully choreographed with the first movement of the rocket. In case the launch was aborted before the rocket had left the pad, and the dangerous propellants have to be drained from the vehicle, there would be no need to re-attach propellant lines.
All fueling operations on the Proton launch complex were designed to be conducted remotely and the fumes generated in the process can be captured and directed to a special deactivation facility. (112)
A view of Pad 39 at Site 200 in September 2017.
A Proton rocket arrives at Site 81. Copyright © 2000 Anatoly Zak
The Proton rocket is being installed on the launch pad. Copyright © 2000 Anatoly Zak
The 8U260 launch pad erector is lowered down to its stored position after the installation of the Proton rocket on the pad. Copyright © 2000 Anatoly Zak
Service tower moves into position around the Proton rocket after it has been installed on the launch pad. Copyright © 2000 Anatoly Zak
A close-up view of the launch pad interface with the first stage of the Proton rocket. Click to enlarge. Credit: Roskosmos