NASA weighing SLS Green Run versus EM-1 schedule risks – NASASpaceFlight.com

NASA is officially still in the process of implementing the Space Launch System (SLS) Core Stage. "This is why we test" is an oft-quoted philosophy in this phase of development of a new system; in the year 2020, the agency revisited whether or not to continue to apply SLS.

Up until recently the "Green Run" or acceptance test of the stage is considered to be a critical development step in the program for the newest and most complicated part of the launch vehicle The Stage Green Run would be the culmination in the one and only planned hot-fire test of a Core Stage before EM-1.

Delivery of the first Core Stage by prime contractor Boeing has been delayed, and NASA was hoping for both play catch up and speed up plans for a US crewed lunar landing in 2024. The agency conducted a 45-day study that concluded in mid -April to be able to recover some EM-1 launch date target within 2020.

NASA is reportedly leaning towards the end of the test, which has not yet been announced. Although the mission is uncrewed, it is crucial for SLS to fully deliver in its first launch.

Green Run is for the rookie internship, not the veteran engines

"Green Run" in this case is for the Green Stage Internship and the test campaign is focused on testing the internship, not the engines. A Green Run is an acceptance test of new hardware and for liquid propulsion system testing at the Stennis Space Center in Mississippi the term can be applied to everything from acceptance testing new components to new engine builds to new rocket internships like the SLS Core Stage.

The Aerojet Rocketdyne RS-25 engines are one of the only Core Stage systems that are ready to fly today because they have finished their testing a long time ago. The four flight engines (Engines 2045, 2056, 2058, and 2060) that will be installed in the first Core Stage have been demonstrated multiple times on Space Shuttle launches when they were called Space Shuttle Main Engines (SSME).

(Photo Caption: The Four RS-25 Flight Engines Assigned to EM-1 as "delivered in place" in October, 2017, at Aerojet Rocketdyne's facility at Stennis.)

Two ground-only "development" engines (Engines 0525 and 0528) led to the development of SLS in both nominal and off-nominal conditions. Hot-fire testing of the RS-25 "adaptation" that will be ready for you SLS launches concluded eighteen months ago.

These single-engine tests from 2015 through 2017 are qualified by the SLS operating conditions, including their new engine controller units (ECU). The single engine testing in the A-1 booth at Stennis typically uses the development engines instead of testing them to the edges and corners of its operating envelope.

Using development engines avoids both general use and the use of additional equipment; However, two RS-25 flight engines that did not fly during the Shuttle Program were standalone engine Green Run tests. These acceptance tests further demonstrate the safe operation of RS-25 flight hardware to SLS requirements.

A third flight engine was tested during testing in a calibration test of the A-1 stand.

In addition to the RS-25 engines, the SLS Boosters and the Interim Cryogenic Propulsion Stage (ICPS) also have an extensive ground test history, flight history, or both.

(Photo Caption: The SLS Core Stage and its elements.) Although it is designed around the Space Shuttle Main Engines and some of the other parts of the world. new, including the arrangement of its systems.)

In contrast to the other elements of SLS that are flight-proven or ground-tested, the Core Stage is the new piece of the launch vehicle. It started from behind the scenes and has already been tested.

When finally completed Core Stage-1 will not just be the first article, but also the program's first working internship article. The Green Run of this first stage is the only one planned to show a full-length test of a Core Stage before the program's first launch.

For the integrated hot-fire test, the RS-25 is one of the most important components of the game. Core Stage meets the requirements for the next stage. In addition to meeting the demands of the cluster cluster during mainstage, new SLS will also be able to see its first full use.

The flight of the flight control system and the control of the environment and the control of the environment.

NASA and Boeing are qualified as different interns and interns, but the tests during the Green Internship will be used together.

Nothing official as ASAP makes recommendations

As a part of initiatives to shore up the EM-1 schedule, NASA began an internal 45-day study in early March. Final assembly of Core Stage-1 is still the critical path, and has been revised in the past.

The hope is that it will buy back to the end of the year; however, by past scheduling that would still keep a launch before the end of 2020 in jeopardy. The 45-day study was looking for more and more options and the Green Run Course would be out for anyone looking at content to cut.

NASA Headquarters in Washington, D.C., the SLS Program held an All-Hands meeting on April 22 where it was reported that the test was kept on the schedule. NASA Human Exploration and Operations Directorate (HEO) Associate Administrator Bill Gerstenmaier feels the same day.

NASA says nothing has been decided yet. "A final review of the assessment is still underway," NASA spokesperson Mike Curie wrote in an email following news of the All-Hands meeting.

(Photo Caption: The mated Core Stage-1 engine is a part of the Michoud Assembly Facility (MAF) on the Final Assembly area. and the final assembly sequence is ready for completion, perhaps before the end of the year.)

The ASAP Aerospace Safety Advisory Panel (ASAP) discusses their recommendation for the Green Run Flight Test in Huntsville, Alabama. "Dr. Patricia Sanders, ASAP Chair, said during the public meeting," There is no other test that will gather the critical, full-scale, integrated propulsion system.

"Shorter durability engine engineerings et de la maine de l'exploitation d'exploitation et de l'exploitation de l'exploitation de l'exploitation d'exploitation et de la gestion des margins. NASA to retain this test. "

The Core Stage production schedule has been a critical path for a long time and has a long history of flight. Space Center instead of the Green Run in hopes of getting back some of the time lost. Although static fire tests have been established before the start of a new program or a new vehicle, they have been preceded by more thorough acceptance tests.

The Space Shuttle Program runs a twenty-second long FRFs on the Main Propulsion Test Article (MPTA) through several ground test-firings in the late 1970s and early 1980s in the B-2 test stand. SpaceX still performs flight-duration acceptance tests of courses in Texas before the pre-launch.

The Delta 4 program used the same Stennis B-2 stand to hot-fire a Common Booster Core (CBC) first stage to the first program and a pre-launch FRF. The Saturn program also took place in the 1960s, including what is now called the Stennis Space Center.

(Photo Caption: The Space Shuttle Main Propulsion Test This article was used to conduct long-duration, integrated propulsion system test firings at Stennis.The left image shows the orbiter aft fuselage built and integrated for the MPTA being lifted into the B-2 Stand in 1977. The aft fuselage, analogous to the SLS Core Stage engine section, was developed with a truss structure so it could be attached to a Shuttle External Tank. were merged into a bigger, inline design.)

An FRF on the pad at KSC would be limited. The water supply for the deletion and the deluge of the flame trench and launch platform at KSC is designed and sized for the fast and easy way. It will run out after only seconds of engine run time.

As with Shuttle, SLS does not throttle up to full power until after liftoff; when the test is throttle the engines up to 109 percent of rated power level (RPL) and try to replicate a flight-like throttle profile, it's unclear if KSC can support full power during a hypothetical FRF.

During the ASAP's meeting with NASA earlier in the week, Dr. Sandra Magnus may have referred to the understanding of the operational margins that Dr. Sanders stated in her opening remarks.

NASA's Commercial Crew Program (CCP), Dr. Magnus, to form Shuttle Astronaut who flew on the program's final flight. that we understand the margins, that we are controlling those margins, and that we are operating in the environment that those margins require. "