NASA is requesting industry proposals for a Universal Stage Adaptor (USA) that will provide options for additional payloads set to ride uphill on the Space Launch System (SLS). The USA will be able to host payloads in-between the Exploration Upper Stage (EUS) and Orion, or provide a role for cargo-only missions – the latter required to provide SLS with a viable flight rate.



USA for SLS Block 1B:

The Space Launch System (SLS) is NASA’s next flagship launch vehicle, with a key task of launching astronauts on deep space exploration missions for the first time since Apollo.

SLS will initially launch in its Block 1 configuration, a 70 mT capable rocket that will debut in 2018 on an uncrewed test flight. However, its workhorse configuration is the Block 1B – raising the capability to at least 105 mT.

NASA is planning for an eventual full evolution to the Block 2 configuration, with its 130 mT capability classed as a requirement for Mars missions in the 2030s.

For the 2020s, the Block 1B will be the SLS configuration of choice.

The Block 1B will be utilizing the Exploration Upper Stage (EUS) for both crew and cargo missions, with the Universal Stage Adaptor (USA) providing SLS with a method to fully realize the Block 1B’s capability.

With planning progressing on the Block 1B, NASA is now looking for industry to provide proposals on the USA.

“(The USA is) a separable adapter which provides a structural interface between the EUS and Orion (that) can accommodate co-manifested payloads (significant mission elements such as habitats, communications satellites, in-space telescopes, etc.) and secondary payloads (cubesats or equivalent ‘small’ science or engineering experiments), and allows for the deployment of payloads from within the adapter,” noted the RFI documentation.

“(It should) accommodate a payload attach fitting to accommodate co-manifested payloads and allow for deployment of the payload from the attach fitting.”

The USA will be required for several roles, such as cargo-only missions, which would result in a payload fairing-type design, incorporating a payload attach fitting to accommodate co-manifested payloads and allow for deployment of the payload from the attach fitting.

It should also be used for Orion-only missions, utilizing the baseline USA concept in a fixed (non-separating) adapter which will provide a structural interface between the EUS and Orion.

Despite the immense power of the SLS Block 1B, NASA will still require the USA to be a “mass-efficient” interface – that will also provide shielding from the external environments.

In what is a typically NASA-worded request, the USA would need to be “designed, developed, built, and certified for flight consistent with NASA design, construction, workmanship, and qualification standards and other technical and programmatic requirements associated with human rating considerations including configuration management, reliability analysis, and safety assessment processes.”

Those requirements provide the bulk of the industry RFI’s (Request For Information) content, not least because it “will require the rigor of man-rating”.

One interesting reference in the documentation relates to the timescale as to when requires the USA.

“NASA is interested in a first launch of the Baseline USA as part of the SLS Program in 2021 and follow-on flights at a rate of up to one per year,” a reference that continues to back NASA’s preference to move to the EUS as soon as possible.

The flight rate is also telling, with NASA plans continuing to show a preference to launch SLS on alternate crew then cargo missions throughout the 2020s.

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However, due to the lack of manifested missions, this plan is only envisioned and remains subject to change until the schedule – past EM-1 – is solidified.

Only last year, NASA’s Associate Administrator for Human Exploration, Bill Gerstenmaier, warned SLS will require a “repetitive cadence” of at least one launch per year as a necessity.

While Orion missions have an intial goal of working towards the upcoming Asteroid Redirect Mission (ARM) in the 2020s, Cargo missions may include flagship science missions.

With no payloads past the EM-2 flight currently revealed, SLS managers have been quick to both promote SLS’ unique capability to potential military and commercial customers, and to the science community.

The most notable option is a possible marriage between SLS and the proposed Europa mission. Meetings between the relevant departments – via Technical Interchange Meetings (TIM) – have been progressing throughout the summer months.

Such evaluations are commonplace, with SLS teams working notional Design Reference Mission (DRM) parameters to find missions for the Heavy Lift Launch Vehicle (HLV) in the 2020s.

A key issue continues to be the cost impact to such missions, especially with highly capable – and less expensive – launch vehicles set to come online in the coming years.

(Images: Via L2 content (lead image, EUS and SLS in her correct appearance (unpainted core) from L2 member Nathan Koga) and from 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: http://www.nasaspaceflight.com/l2/)