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The Russian Soyuz TMA-19/23S spacecraft has been relocated from the Zvezda module to dock with the Rassvet (MRM-1) research module during a 30 minute maneuver on Monday. Meanwhile, International Space Station (ISS) managers have been made aware of a Change Request (CR) for preliminary design, integration, and delivery concepts for the addition of Node 4 later this decade.

Soyuz TMA-19 Relocation:

The scheduled event of freeing up the Service Module’s Aft port – for the arrival of the resupply vehicle Progress M-06M/38P on July 1 – resulted in the debut docking of a Soyuz to the MRM-1, the module which arrived with Atlantis on STS-132 in May.

Mini Research Module 1 (MRM-1) was manufactured from the residual Dynamic Test Article of the Science Power Platform (SPP). Rassvet – and 1400 kg of NASA cargo launched inside (6.0 m3 of usable on-orbit stowage volume) – was successfully moved from Atlantis’ Payload Bay and installed on the ISS during Flight Day 5 of the mission .

During STS-132 and the Expedition 24 stage, crewmembers removed the array of cargo from the inside of MRM-1, making the required room for Soyuz crews to transition through into the ISS.

Other preparations for the event included Fyodor Yurchikhin, Doug Wheelock and Shannon Walker conducting a three hour rehearsal for their short flight in the Soyuz TMA-19 – including formal a training drill comprising a procedures review, flight data review, tag-up with ground instructor and onboard simulator training on the RSK1 laptop.

“Due to the currently very high solar Beta angle period with its increased thermal loads on the station, the standard relocation maneuver profile/template was changed for the new Beta-caused ISS attitude mode. The latter will be “earth-fixed” LVLH attitude instead of the usual “space-fixed” Inertial mode, i.e., with the ISS continuing to pitch down in orbit rate (~4 deg/minute) to remain “locally horizontal”,” noted ISS status reports ahead of the flight.

For the docking, the Soyuz had to match the station’s very slow pitch-down rotation, although the maneuver was delayed due to a problem with a Beta Gimbal Assembly (BGA) driver, which failed to latch the 4B array in place.

Following the clearance of the issue, Yurchikhin issued the manual undocking command, prior to physical separation from the SM Aft port, utilizing a pushrod delta-V of ~0.12 m/s.

“Soyuz TMA-19/23S relocation was completed without incident, although delayed by 75 minutes due to a stall of the 4B BGA motor as it was moving the 4B solar array to its latched position,” added ISS status.

“After system recovery by ground control, it took the array some time to reach its final position, delaying the undocking from 5:58 PM GMT to ~7:13 PM GMT. It freed up the SM Aft port for the arrival of Progress M-06M/38P on 02/07 (Aft port being more advantageous for using Progress for reboost/debris avoidance maneuvers).”

This was followed by a flyaround to the MRM-1 Nadir port at a range of 30-50m from the station, ending at station-keeping. Final approach led to contact and capture at 2:38pm Central.

Node 4:

Currently, the final module that will take up residency on the ISS is the ‘recent’ manifest addition of flying the PMM (Permanent Multi-purpose Module) with Discovery on STS-133. However, preliminary discussions are taking place on another addition to the orbital outpost later this decade.

Node 4 – otherwise known as the Docking Hub System (DHS) – is currently being baselined as launching on a medium EELV (Evolved Expendable Launch Vehicle) – likely to be a 5×1 variant of an Atlas V, but potentially a Delta IV – in tandem with a yet-to-be-decided “Tug”, possibly utilizing the ARDV (Autonomous Rendezvous & Docking Vehicle) concept, which could be launched on an Atlas V.

Other solutions include potential concepts involving either the European ATV (Automated Transfer Vehicle) or HTV (H-II Transfer Vehicle) with the pressurized module removed.

“I wanted to make you aware of an ISS program CR coming down the pipe. This CR requests funding for the preliminary design, integration, and delivery concept of the Docking Hub System (DHS),” noted a memo acquired by L2. “If you’ve heard of it you might have heard it called “Node 4”.

Currently, a 40 month schedule is being evaluated, which would target launch in the second half of 2013 – although such a timeline is deemed to be ambitious.

“The CR calls for an 11 month design phase which would take the project through PDR (Preliminary Design Review). In talks with the CR initiator though he mentioned the CR will be scaled back to a six month design phase focusing on systems requirements and delivery to ISS concepts,” added the memo. “The whole project is intended to be on a 40 month design/manufacture/delivery schedule.

“We’re not asking the individual disciplines to evaluate this CR as it is very preliminary in the design cycle for the DHS. Disciplines will be asked to evaluate subsequent CRs that come out and we expect that MOD work/needs in the future will include simulators/mockups, displays, flight techniques for rendezvous and crew monitoring, and any other standard product updates associated with adding a new module.”

The memo also notes that the effort will be based around utilizing the Node Structural Test Article (STA) – currently located at the Kennedy Space Center (KSC), for an eventual docking on Node 2 Forward.

“Basic concepts I’m aware of at the moment: The DHS would use the Node Structural Test Article (STA) as its base structure. The STA has been delivered to KSC and is being evaluated for what needs to be done to make it flight capable,” the memo continued.

“The DHS would be installed on Node 2 Forward. The DHS would utilize the new docking mechanisms being standardizes as part of the International Docking System Standard (IDSS).”

Numerous considerations will take place over the interim period, including the current evaluations for the potential need to relocate Station assets, such as Cupola, due to docking conflicts with future vehicles – namely Orbital’s Cygnus – with an article based on an expansive L2-acquired presentation being prepared for publication after the Space Station Program Control Board (SSPCB) meeting this week.