Working the paper trail – SLS team processing thousands of CDR documents

by Chris Bergin

The Critical Design Review (CDR) for NASA’s Space Launch System (SLS) is underway, with managers and engineers wading through huge piles of documentation. The process is expected to last through the summer and is expected to pass without any major technical issues, as the vehicle prepares for her maiden launch in 2018.


The review at NASA’s Marshall Space Flight Center (MSFC) comes after each major element of the rocket system passed their own specific review process.

The vehicle had already passed its Preliminary Design Review (PDR) with a good report card, a key difference to the troubles suffered during the Constellation Program (CxP). SLS is now well past the point at which the Ares launch vehicles were canceled.

2015-03-16 18_42_26-L2 Level_ Space Launch System Update Notes And Discussion - Sept, 2014 onwardsSLS then passed through the KDP-C (Key Decision Point -C), setting the path towards the upcoming CDR – arguably the biggest milestone for the rocket’s development and approval to head into production.

Preparations for the CDR have been ongoing for months, throughout all of the rocket’s major elements.

All deliveries of documents, drawings – and other review items for the data pack – were collated by the end of April, ahead of the CDR kickoff presentation took place this week.

The CDR will confirm the maturity of the design is appropriate to support proceeding with full-scale fabrication, assembly, integration, and testing.

The review also baselines all the work that has taken place over the recent years, work that has matured SLS into set configurations throughout her evolvable lifetime that is expected to result in a career that is envisioned to last until the 2040s.

“We’ve never said building a rocket is easy,” noted SLS Program Manager Todd May. “We pore over every part of this rocket during these reviews.

“Thousands of documents and months of time are put into making sure the design is sound, safe and sustainable, and will make NASA’s mission of furthering human spaceflight possible. We are making advances every day on this vehicle.”

2015-05-15-202910Thousands of documents isn’t an understatement, with one source claiming over 60,000 pages of documentation have been collated in the run up to the CDR.

Notably, SLS is now shown in official documentation in her correct appearance, with an unpainted core. (Image left – Nathan Koga L2 Rendering, based on image right showing official NASA documented SLS).

Most of the documentation is restricted to internal use, but some useable documentation provided to this site shows an array of meetings will take place throughout the coming weeks, resulting in the CDR Board milestones taking place in July. This will be the point at which managers can claim the CDR has passed.

Further meetings are scheduled through to September, resulting in briefings at the Agency level. Ultimately, NASA administrator Charlie Bolden and his political paymasters will have to sign off on the CDR’s results.

2015-02-20 17_11_32-L2 Level_ Space Launch System Update Notes And Discussion - Sept, 2014 onwardsThis week’s major kick off meetings involved three days work, discussing 21 major elements in front of SLS’ top brass. Each element has numerous subsections, with a Q&A following each presentation.

The presentations were mainly of the overview nature, given each element for the rocket – including boosters, engines, stages and Spacecraft and Payload Integration & Evolution (SPIE) – has already undergone their own reviews before the kickoff of the integrated program review.

While these meetings take place, work is continuing on the hardware that will make up the SLS rocket.

Testing of SLS’ RS-25 main engines is about to enter its second hot fire test, with E0525 set to fire up on May 28.

The engine team also recently gave birth to an additional RS-25 from spare parts, bringing the stock of engines up to 16, prior to buying in the expendable RS-25E engine to stock up the inventory, which is currently in a procurement process with a single supplier – Aerojet Rocketdyne.

“The assembly of the first new RS-25 flight engine 2063 for SLS was completed. This is also the first RS-25 engine completely assembled from available parts since Sep 20, 2010,” noted L2 information.

“This engine joins a fleet of 15 other legacy engines, 14 of which have already flown to space numerous times on various Space Shuttles during the 135 missions of the Shuttle era. All of the legacy engines are being upgraded with a state of the art engine controller and improved thermal insulation.”

2015-03-16 19_05_04-SLS VAC - Google SearchWork on the tankage for SLS is currently evaluating its flow schedule, following a “Recovery Decision Meeting” relating to the massive Vertical Assembly Center (VAC) at the Michoud Assembly Facility (MAF).

This machine is where the Cores and tankage for SLS will be welded. However, it has been suffering from teething issues, such as alignment problems that required the foundations to be re-laid by the contractor.

“At MAF, VAC Tool handover from construction contractor (ESAB Welding & Cutting) to Boeing is scheduled for August 10,” added the L2 notes.

2015-05-15-203537The five segment solid rocket motors that will pair up as SLS’ boosters recently passed a review of the Qualification Motor -1 (QM-1) Static Fire test and is now working through casting operations with the QM-2 motor, which will be the final test firing before the big boosters will be graduated for flight with EM-1 in 2018.

Also, at ULA’s Decatur facility, manufacturing of the EM-1 flight ICPS (Interim Cryogenic Propulsion System) Upper Stage is scheduled to begin on July 16. SLS is expected to move to the more powerful Exploration Upper Stage (EUS) in the early 2020s.

2015-05-15-204014The EUS will allow SLS to broaden her horizons with both crew and science payload missions, with continued interest in allowing SLS to loft a proposed Europa Clipper mission. The next Technical Interchange Meeting (TIM) is set to take place on June 30, involving numerous parties including JPL.

Mars mission planning is now starting to build up (L2), ranging from mission scenarios to even how and when to conduct waste dumps during the transit to the Red Planet. This work is being conducted by NASA’s Human Architecture Team (HAT).

On the spacecraft side, fabrication work on the EM-1 Orion is also taking place at MAF – marked by the start of Crew Module welds. Orion’s own Critical Design Review (CDR) scheduled to begin on August 3, utilizing data from the successful Exploration Flight Test  -1 (EFT-1) mission.

Images: NASA, Orbital ATK, Lockheed Martin and L2 artist Nathan Koga via L2’s SLS sections, which includes, presentations, videos, graphics and internal – interactive with actual SLS engineers – updates on the SLS and HLV, available on no other site.)

(L2 is – as it has been for the past several years – providing full exclusive SLS and Exploration Planning coverage. To join L2, click here:

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