By Steven Siceloff,
NASA’s Kennedy Space Center, Florida
A metallic ring big enough for astronauts and cargo to fit through is scheduled to fly to the International Space Station in July as part of the cargo aboard a SpaceX Dragon cargo spacecraft loaded with materials for the orbiting laboratory and its crew. The ring is known as an International Docking Adapter, or IDA, and its main purpose is to provide a port for spacecraft bringing astronauts to the station in the future.
The Dragon and its cargo will fly into orbit aboard a SpaceX Falcon 9 rocket that will take about 10 minutes to lift the spacecraft from its launch pad at Cape Canaveral Air Force Station in Florida to an orbit to catch up with the station. It will take about two days for the Dragon to reach the station. Once within reach of the station’s robotic arm, the Dragon will be berthed to the orbital complex by the astronauts already on the station.
Outfitted with a host of sensors and systems, the adapter is built so spacecraft systems can automatically perform all the steps of rendezvous and dock with the station without input from the astronauts. Manual backup systems will be in place on the spacecraft to allow the crew to take over steering duties, if needed.
“It’s a passive system which means it doesn’t take any action by the crew to allow docking to happen and I think that’s really the key,” said David Clemen Boeing’s director of Development/Modifications for the space station.
The IDA stands about 42 inches tall and is 63 inches in diameter on the inside. Sensors and other fittings ring the perimeter of the adapter and give it an overall diameter of about 94 inches. Spacecraft flying to the station will use the sensors on the IDA to track to and help the spacecraft’s navigation system steer the spacecraft to a safe docking without astronaut involvement.
The adapter also represents the first on-orbit element built to the docking measurements that are standardized for all the spacecraft builders across the world. Its first users are expected to be the Boeing Starliner and SpaceX Crew Dragon spacecraft now in development in partnership with NASA’s Commercial Crew Program. Because the adapter is designed to an international standard, future spacecraft will be able to dock there, too.
“It’s really good we have an international standard now that anybody can build against and come dock to the station or to anything that has the same standard,” Clemen said.
The companies are competitors in delivering astronauts to the station, but they both play a large role in the IDA project, with Boeing having built the docking port and SpaceX ferrying it into orbit.
The IDA is comprised of parts from 25 states in the United States. The main element was built by Russian company RSC-Energia, which built the primary structures of the adapter.
While the crew will be able to move the supplies out of the interior, pressurized compartment of the Dragon without leaving the station, the robotic arm will be called on to pull the IDA from the trunk and maneuver it near the port where it will be connected. NASA astronauts currently living aboard the station will perform a spacewalk later this summer to make the final connection of the IDA to the Harmony module.
This adapter will be one of two at the station. Another already being assembled at Kennedy will be carried into orbit during a future SpaceX cargo resupply mission and attached to another open port on the station, giving the station two docking areas for the new generation of human-rated spacecraft. Both of the IDAs are identical.
With the IDA loaded in the rear trunk of the Dragon, the interior of the spacecraft will hold about 3,800 pounds of material including experiment supplies for dozens of the 250 research projects taking place on the station during Expeditions 48 and 49. The payloads are vital elements for the crew on the station to conduct its research for those on the Earth as well as to help advance the knowledge needed for a future journey to Mars by astronauts.
Included in the payload is the TangoLab-1, a research rack that will run small-sized experiments in orbit in a wide range of scientific fields. The rack is tailored to self-contained research that can be accomplished inside canisters about the size of a tissue box. The rack can hold two dozen experiments at once and those can be changed out for fresh research with each arriving cargo spacecraft. According to Space Tango CEO Twyman Clements, the lab is meant to give researchers a new avenue to conduct science affordably in orbit.
“We specialize in doing really complex work in really small space,” Clements said. The idea to design the lab to uniform canister sizes came about from the company’s work in CubeSats and space station projects. “This way we don’t have to re-invent the wheel every time” for a new experiment.