Super Sizing Pegasus for SLS core transport

by Chris Bergin

The famous Pegasus Barge is nearing the end of its jumboisation phase, as work continues to prepare it for a role in transporting the massive Space Launch System (SLS) stages from their birth place the Michoud Assembly Facility (MAF). The upgraded Pegasus is set to transport the first major SLS hardware from New Orleans to the Stennis Space Center for testing as early as next year.

Pegasus Stretch:

Pegasus was specially designed and built for Shuttle External Tanks (ETs), making the 900 mile trip 41 times between 1999 and 2011, delivering 31 space shuttle external tanks: ET-103, ET-105, ET-106, ET-108, ET-110, ET-111, ET-113 and ET-115 through ET-138.

Its final role in Shuttle support operations came via the shipping of the Space Shuttle Main Engine (SSME) ground support equipment to Stennis from NASA’s Kennedy Space Center in Florida.

Pegasus was then mothballed at NASA’s Stennis Space Center in 2011.

Its transition to its next role began last summer, making a short trip to Amelia, Louisiana – where contractors at Conrad Shipyard LLC were tasked with modifications on the barge, part of the $8.5m contract they earned from NASA to prepare Pegasus for its role with SLS.

2014-07-07 19_03_18-pegasus barge nasa - Google SearchAt 260 feet long, 50 feet wide and 15 feet high Pegasus simply isn’t large enough for the role of transporting the large core stages of the SLS.

“Modifications were needed to the barge due to the sheer size of the SLS – which is more than 50 feet taller than the shuttle, and will launch more than three times as much weight into space,” noted Alan Murphy, team lead for the Pegasus project at MSFC.

“The core stage is 59 feet longer and more than 500,000 pounds heavier, including the ground support equipment, than the space shuttle external tank.”

The barges have played a role in transporting hardware since the Saturn era.

2014-07-07 16_40_56-Category_NASA barges - Wikimedia CommonsAt one point NASA had a fleet of barges, such as the Orion, Poseidon, Pearl River and Palaemon.

These barges ferried Saturn IB and Saturn V stages between Marshall Space Center (MSFC); Michoud Assembly Facility (MAF); Mississippi Test Facility (MTF, renamed to Stennis Space Center); and Kennedy Space Center (KSC).

Replacing NASA’s aging Poseidon and Orion barges, Pegasus became the final barge used for transporting the shuttle ETs in 2002. It will be the sole barge used for SLS core transportation, deep into the 2020s.

Modification work will ensure Pegasus will meet the American Bureau of Shipping standards, including load line certification, or verification of the barge’s legal loading limit to safely maintain buoyancy during water travel.

2015-02-04 15_21_14-maf-20140924_pegasus_remod_02.jpg (7360×4912)Stripped down to its bare bones, the Conrad crews have been tasked with installing a new, 165-foot center section for the barge, extending the total length of the barge from 260 feet to 310 feet. A 115-foot center section of the existing barge was removed and the new piece installed.

The first planned set of voyages for the Pegasus will be from MAF – after picking up core stage structural test articles (STAs) – before shipping them to MSFC for testing.

“We look forward to seeing the barge back in the water for a new era of exploration,” added Mr. Murphy.

Z15For the shipping of cores – Pegasus will be aided by the Self Propelled Module Transporter (SPMT) – that will allow for SLS Structural Test Articles (STAs) and the Integrated Core Stage (ICS) to depart MAF to NASA locations.

The SPMT will be able to travel at up to three miles per hour and be capable – when SPMT modules are grouped together – of carrying up to 600,000lbs.

A total of four transporters will be required for the SLS Program.

Production of the hardware for the first STA elements is continuing at MAF, although the schedule has been delayed a few weeks due to an incident involving a bearing coming loose from the giant Vertical Assembly Center (VAC). No one was injured in the incident.

2015-01-02 19_44_33-SLS Structural Test Article Stands at MSFC - Construction Photos and UpdatesPegasus will ship the hardware for testing on two test stands, the tallest – Test Stand 4693 – will be 215 feet tall and will host testing on the LH2 tank.

The shorter 4697 stand – 86 feet tall – will be used to test the LOX tank and forward skirt.

Both of these test stands are currently under construction at the Marshall Space Flight Center.

The barge also will deliver the flight core stage from Michoud to Stennis, where it will be tested in late 2016 and early 2017 on the B-2 test stand.

The core stage will be installed on the stand – currently undergoing its own modifications – for propellant fill and drain testing and a hot fire test.

The Green Run testing on the B-2 test stand will see the four RS-25 engines on the first Core Stage fired for a full mission duration of approximately 500 seconds.

Stennis recently celebrated the return of RS-25 testing via the hot fire of unit E0525.

For the debut flight – known as Exploration Mission-1 (EM-1) – NASA’s Liquid Engine Office has selected the first four engines that will loft the monster rocket uphill.

Z3The four engines – ME-2045, ME-2056, ME-2058, and ME-2060 – are all established Shuttle veterans with numerous successful missions under their belts.

A total of 15 RS-25Ds left the Kennedy Space Center (KSC) for their new role, arriving at the Stennis Space Center in 2012.

Once testing of the EM-1 core is complete at Stennis, the Pegasus will transport the stage to Kennedy Space Center for preparation and integration into the SLS flight vehicle in the Vehicle Assembly Building (VAB).

EM-1 is currently set to launch in July, 2018.

(Images: Via L2 content from L2’s SLS specific L2 section, which includes, presentations, videos, graphics and internal – interactive with actual SLS engineers – updates on the SLS and HLV, available on no other site. Other images via NASA)

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