With the lifespan of the International Space Station (ISS) extended to at least 2024, NASA officials have begun evaluating options for the next phase of Commercial Resupply Services (CRS), allowing for the orbital outpost to be stocked up with supplies and equipment after the current CRS deal with SpaceX’s Dragon and Orbital’s Cygnus spacecraft expires.



CRS2:

Following the direction to phase out the Space Shuttle Program (SSP) at the completion of ISS assembly, NASA set up the Commercial Orbital Transportation Services (COTS) program, part of a wider effort to free the Agency from Low Earth Orbit (LEO) operations, allowing NASA to refocus on deep space exploration.

The COTS program played a huge role in developing new spacecraft towards the goal of commercial cargo and crew capabilities, with an initial priority of resupplying the ISS as part of an international effort.

The development of the commercial resupply element resulted in agreements being signed between NASA and SpaceX – with their Dragon spacecraft, along with Rocketplane Kistler (RpK) – and their K-1 vehicle.



However, NASA managers opted to terminate the deal with RpK, eventually signing up one of the other contenders, Orbital – with their Cygnus spacecraft.

The Orbital deal to carry out ISS resupply flights – under the $1.9 billion CRS contract – called for eight missions carrying approximately 20,000 kg of cargo to the ISS. SpaceX were awarded $1.6 billion to conduct 12 Dragon resupply runs to the Station.

Both Orbital and SpaceX had to prove they could safely send their new spacecraft to the $100 billion Station, with Dragon conducting two COTS flights to pass a series of communications, rendezvous and berthing objectives.

Orbital’s Cygnus spacecraft conducted one COTS mission prior to receiving a green light to begin CRS flights.

Both vehicles are now fully operational, with SpaceX currently preparing to launch their third CRS mission (CRS-3/SpX-3) to the ISS, while Orbital recently completed their first CRS mission (CRS-1/ORB-1).

Even before ISS was – as expected – extended to conduct operations through to at least 2024, the question of adding more commercial flights was always on the cards.

With the additional lifetime of the ISS confirmed, NASA managers have begun to evaluate a second salvo of commercial resupply missions under what is known as CRS2, allowing for early discussions on how the Agency can ensure a smooth continuation of supplies heading uphill from US soil.

“Over the past two years, NASA and its American industry partners have returned International Space Station resupply launches to U.S. soil, established new national space transportation capabilities and helped create jobs right here on Earth,” noted a NASA release introducing the evaluations into CRS2.

“In January, the Obama Administration announced plans to extend the life of the space station through at least 2024 – marking another decade of discoveries to come that will benefit Earth while increasing the knowledge NASA needs to send astronauts to an asteroid and Mars.

“NASA has issued a Request for Information (RFI) seeking industry feedback on options to meet the future needs of the International Space Station for cargo delivery of a variety of new science experiments, space station hardware and crew supplies.”

CRS2 will cover services from 2017 through 2024, with the NASA RFI noting the Agency may elect to have one contract or multiple contracts to meet the requirements.

The document also notes the Agency expects to allocate between $1.0B and $1.4B per year to facilitate these services.

CRS2 outlines call for the delivery of 14,250 to 16,750 kilograms (kg) of pressurized cargo, along with 1,500 to 4,000 kg of unpressurized cargo per year.

The current scenario involves Orbital’s Cygnus ending its missions via a destructive re-entry, taking with it a full compliment of trash for disposal. However, SpaceX’s Dragon is capable of returning downmass via its safe re-entry and splashdown off the coast of California.

Sources also note discussions have – and will continue – to take place between NASA and SpaceX, per the potential of a larger trunk on Dragon, in order to enable larger Orbital Replacement Unit (ORU) transportation uphill to the outpost.

The CRS2 document notes that the Agency is looking at a requirement that would result in the return/disposal of up to 14,250 to 16,750 kg of pressurized cargo and the disposal of 1,500 to 4,000 kg of unpressurized cargo per year.

The RFI outlines the aforementioned services will be conducted over four to five missions per year.

While SpaceX and Orbital are likely to be front runners for the CRS2 contract, the RFI provides additional requirements and outlines that could foster possibilities for other commercial vehicles to compete for the roles.

“ISS will maintain the capability to support a berthing and a docking capability as physical interfaces to the ISS. Service providers must be compatible with both prime and backup attachment ports,” the document added.

“Berthing will be to a Common Berthing Mechanism (CBM). Docking will be to the new International Docking Adapter (IDA).”

This allowance for berthing and docking vehicles opens up the potential for other commercial vehicles, such as Boeing’s CST-100 – which is currently competing for the right to launch NASA astronauts to the ISS.

SNC’s Dream Chaser is also aiming to provide crew launch capability, while also positioning itself for a multi-role path that could include cargo flights – as much as the vehicle hasn’t been associated with CRS level missions.

Dream Chaser can launch and land with or without crew, on cargo only or combined missions. She would also bring another downmass option to the table.

The CRS2 scenario could also reopen the potential of ATK’s Liberty space system making another attempt to win a NASA contract.

Despite the lack of news over the last few years, sources note the project is still alive, although it will only progress when customers are forthcoming.

A potential use of Liberty for CRS missions would likely relate to the extended cargo configuration, allowing the Liberty spacecraft to take full advantage of the launch vehicle lift capacity to transport a pressurized pod – the Liberty Logistics Module or LLM – along with the composite crew module.

Based on NASA’s 15-foot diameter Multi-Purpose Logistic Module (MPLM) design, the LLM will include a common berthing mechanism (CBM) and will be capable of transporting up to 5,100 pounds of pressurized cargo.

With that capability, the LLM could be used to transport four full-size science racks to the ISS.

Although the Mobile Launcher (ML) Liberty was set to use for launches is now fully part of the Space Launch System (SLS) program, L2 information notes a back up plan had been evaluated, allowing Liberty to be stacked in High Bay 1 in Kennedy Space Center’s Vehicle Assembly Building (VAB), launching from Pad-39B via a modified Shuttle Mobile Launch Platform (MLP).

Other interesting items listed in the document include a Launch on Need (LON) capability, required within two months of the previous flight. Vehicles will also be required to be able to be mated to the ISS Mission for 45 to 75 days.

Responses to the RFI is due by close of business on March 21, 2014.

(Images: L2, RpK, ATK, SpaceX, NASA and SNC)

(Click here: http://www.nasaspaceflight.com/l2/ – to view how you can access the best space flight content on the entire internet and directly support NASASpaceflight.com’s running costs)