NASA interested in payload fairing options for multi-mission SLS capability

by Chris Bergin

SLS managers have asked the aerospace industry for information about the potential use of existing payload fairings for the Heavy Lift Launch Vehicle (HLV). It is hoped that differing fairing options will allow SLS to launch numerous missions outside of its role with the crewed exploration roadmap, missions that require the superior lift capability of the monster rocket.

SLS Fairings:

NASA is exploring options for larger payload fairings to enhance the cargo carrying capabilities for science instruments and other exploration payloads to destinations including Lagrange points, the moon, asteroids and ultimately Mars.

“This is a no-cost examination of the aerospace landscape to identify existing components that could augment the rocket’s architecture as we move beyond the initial Orion configuration,” said Todd May, SLS program manager at the Marshall Center.

“SLS can make challenging human and science missions possible in large part because of the unprecedented size of the payload it can lift. We are hopeful industry may offer some innovative and affordable ideas about alternative fairing and adapter options.”

NASA claim larger payload fairing sizes enabled by SLS could reduce experiment design complexity and the rocket’s high performance can decrease travel time and, by extension, cost and risk of science missions.

SLS’ drive for viability requires it to be a multi-mission capability launch vehicle, given its Beyond Earth Orbit (BEO) role is – at least based on the sketchy details of the current evaluations into the exploration roadmap – only utilizes part of its flight rate capability.

Ironically, CONOPS (Concept Of Operations) documentation notes SLS is only capable of launching twice a year, as much as that restriction should be mitigated by the time it is required for multiple launches within a set period of time for Mars missions.

However, for at least the first 10 years of its projected existence, SLS will only rise to the lofty heights of one launch per year, based on its role with Orion and exploration roadmap-based missions. As such, the addition of science missions – missions that require a ride on the 70mt to 105mt of SLS Block 1 and Block 1A/B – would be a major shot in the arm for the monster rocket.

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With NASA’s Glenn Research Center responsible for payload fairing development for SLS, a Request For Information (RFI) was sent out this month, asking for industry input into matching different payload fairing options to the SLS.

The potential is for SLS to move outside of its baselined 8.4m diameter fairing, to include the sizes such as 5m diameter – allowing for heavy payloads to be sent deep into space.

“One alternative is to utilize an existing available payload fairing and adapt it as necessary – such as a conceptual 5 Meter (16.4ft) Class fairing adapted for SLS cargo missions,” noted the RFI. “In addition the fairing barrel length should be 10m (32.8ft) or greater.

“The fairing may interface directly to the top of the Interim Cryogenic Propulsion Stage (ICPS) Liquid Hydrogen (LH2) tank or to the top of the Launch Vehicle Stage Adapter (LVSA) depending on the most affordable approach to carry loads down through the vehicle. It is also desirable that the payload fairing be able to reduce external acoustic environments by 12 dB OASPL (Overall Sound Pressure Level) or greater.”

The 5 meter payload fairing size has been seen in numerous SLS presentations over the past year. although no specific payloads have been mentioned in such conceptual options.

However, the 8.4 meter payload fairing option is a more familiar sight for SLS cargo missions, with NASA also requesting options around that size.

“Capabilities for SLS cargo missions using an 8.4m (27.6ft) diameter payload fairing (relates to) a 17.3m (56.6ft) non-separable lower fairing and separable upper fairing configuration,” added the information.

“The fairing interfaces with the Interim Cryogenic Propulsion Stage (ICPS) which is mounted on top of the Launch Vehicle Stage Adapter.

“It is also desirable that the payload fairing be able to reduce external acoustic environments by 12 dB OASPL or greater.”

A long list of requirements for the 8.4 meter option include the need to have access doors built into the fairing, likely to be used for pad access during integration or the pad flow.

“PLF Payload Access – Cargo Door: The PLF shall accommodate payload access with a single (1) removable cargo door of 223.5cm (88in) (w) x 177.8cm (70in) (h) in the center of the PLF barrel section.

“PLF Manned Payload Access – Man-Sized Door: The PLF shall accommodate access to the payload compartment with two (2) removable man-sized access doors of 91.4cm (36in) x 91.4cm (36in) spaced within a 30 degree arc of the cargo door.”

To date, the only documented references to SLS being used for ambitious science missions has been the Exploration Systems Development (ESD) Design Reference Mission (DRM) options for deep space presentation (L2), within SLS’ CONOPS outlines.

That documentation cited such mission capabilities involving payloads to the moons of Jupiter and Saturn, namely Europa and Enceladus.

“The SLS could potentially enable sample return from Jupiter’s moon Europa, because it would have the payload capacity to provide shielding for a lander on the surface, and sufficient fuel for propulsive maneuvers out of the gravitational well of Jupiter,” noted the CONOPS presentation.

“At Enceladus, a small active moon of Saturn, the SLS could carry the fuel needed to slow down for sample capture from the plumes on Enceladus, or create an artificial plume on either Europa or Enceladus by firing a copper projectile at the surface.”

NASA managers are yet to release any firm exploration plans – past the ideals of missions to a Near Earth Asteroid (NEA) and Mars.

(Images: L2’s SLS Sections, NASA and Boeing)

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