Current docking arrangements on the ISS. (NASA)
Since the crew switch-over in mid-April, Peggy Whitson has been in command of the ISS and operational leader of Expedition 51. With the departure of Soyuz MS-02 earlier, that left three crew on the station to begin the Expedition 51 adventure: NASA astronaut (and station commander) Peggy Whitson, and flight engineers Oleg Novitskiy (Roscosmos), and Thomas Pesquet (ESA). While the crew awaited reiforcements from Earth, they continued biological and technical experiments, and important maintenance for an upcoming EVA on May 12.
Once again spaceships left Earth to take supplies and new crewmembers to the station. First off the pad (LC-41) was Orbital ATK's Cygnus cargo spaceship, riding atop an Atlas V rocket, on Tuesday April 18. A couple of days later, on April 20th, SOyuz MS-04 blasted off from Baikonur carrying two new crewmembers, Fyodor Yurchikhin (Roscosmos) and Jack Fisher (NASA).
Last minute photos before the roll-out of the rocket that will carry them to orbit. Yurchikhin (L) and Fisher (R). (NASA)
The Cygnus cargo ship was already in orbit when the Soyuz blasted off the pad. But this time, unlike the previous several launches, there were no more new tests to do certifying the advanced Soyuz, so the craft entered a fast-track six-hour orbital path to the station. Cygnus was on a slow approach that would bring it to the station several days later.
The tried-and-true Soyuz arcs upwards on a fast trip to the station. (NASA)
Soyuz MS_04 arrives at the station (NASA TV)
Six hours later, at 7:18 am Mountain daylight time, MS-04 finally docked at the Poisk module on the ISS. Crewmembers began the seemingly long process of equalizing pressures and turning off the propulsion systems. Three hours later the hatches were opened and Expedition 51 had a total of five crew on board. This was Yurchikhin's fifth trip to the space station, and this was Fisher's first trip to space.
NASA TV image of Cygnus spaceship maneuvering into position after reaching the station.
On Saturday the 22nd, The Cygnus spacraft had arrived at the station. Using the robotic arm, Peggy Whitson and Thomas Pesquet grappled the cargo ship and brought it to its docking port on the Unity module. The cargo ship was named the John Glenn, after the famous Mercury astronaut who had passed away last year. The cargo amounted to 7,600 pounds of supplies, fuel, air, and experiments. It will stay at the station for about three months while it is unloaded, and garbage stored back into it.
On April 24, a special moment arrived for the station. Astronaut Peggy Whitson broke the record for US astronauts cumulative time in space, marking 535 days total on her several missions. During the day she received a congratulatory call from President Trump at the Whitehouse. Congratulations to Commander WHitson on this incredible achievement!