With all three Space Shuttle orbiters now tucked away inside their respective museums, the International Space Station (ISS) has completed its full year on-orbit in the post-Shuttle era, a year which has brought great successes for the orbital outpost. On the back of these successes in 2012, a promising 2013 awaits the station, with many new capabilities and technologies set to be demonstrated.

2012 on the ISS:

By far the biggest event to occur on the ISS in the past year was the successful rendezvous and berthing of the SpaceX Dragon capsule to the station, thus demonstrating the ability of a commercial company to resupply the ISS in the post-Shuttle era, a vital capability that needed to be proven in 2012 in order to ensure the provision of adequate logistics for the orbital outpost.

The long-promised era of commercial resupply of the ISS – originally scheduled to be demonstrated prior to the retirement of the Space Shuttle fleet – had been so long coming, having been repeatedly delayed from 2008, to 2009, to 2010, to 2011, and finally to February, March, April, and then May of 2012, left many open questions about the validity of handing off ISS resupply to the commercial sector, and the security of the ISS logistics flow without the Space Shuttle.

However, 2012 will go down in history as the “year of the Dragon” – a year when such fears were massively alleviated (though not completely eliminated) by the long-awaited arrival of the SpaceX Dragon spacecraft at the ISS – and not just once, but twice.

It all started on the 22 May, when the Falcon 9 booster carrying the Dragon capsule for the C2+ mission – also referred to as the SpX-D mission – lifted off from Cape Canaveral Air Force Station (CCAFS) under a blanket of darkness.

Riding inside the Dragon capsule was some non-critical supplies for the ISS, but perhaps the most valuable cargo on that flight was ten years of work by SpaceX, six years of effort under NASA’s Commercial Orbital Transportation Services (COTS) program, the very security of the ISS in the post-Shuttle era, and the hopes and dreams of engineers and spaceflight fans the world over.

Originally planned as two separate flights – C2 to fly beneath the ISS, and C3 to rendezvous and berth with the ISS – the stakes for the ambitions C2+ flight could not have been higher.

While the cargo aboard the flight was not critical to the ISS, since the station already had a good stockpile of supplies to see it through 2012 thanks to the large delivery of cargo by the final Space Shuttle flight, STS-135, the consequences of a mission failure would have been far greater from a PR perspective.

As the first commercially-built vehicle to attempt to reach the ISS, SpaceX and their Dragon had become the “litmus test” for the entire policy of retiring the Space Shuttle and placing ISS resupply in the hands of commercial partners – although the idea of evaluating said policy based on a single test flight was regarded amongst spaceflight circles as both unwise and unfair.

However, for better or worse, SpaceX would have to shoulder that weight for the C2+ flight.

Had the mission failed, while the impacts to the ISS itself would have been minimal, the reverberations would have been far more severe, as politicians would have immediately begun to question the decision to spend any amount of money on both the commercial cargo and crew programs.

Reporters and pundits would have declared that the commercial sector was unable to safely carry cargo and crew into space, that the ISS would have to be abandoned, and that NASA had wasted its money on the COTS program. The loss of confidence in the entire new space industry would have been evident.

As the Falcon 9 rose into the night sky above CCAFS in Florida, the spaceflight community held its breath, aware that every second that ticked by was a second closer to avoiding the aforementioned scenario. Each flight event that passed by brought a slight relief – first stage separation, second stage ignition, nose cap jettison, second stage cutoff, and..spacecraft separation!

As live video relayed images of Dragon’s pontoons being released and solar arrays being deployed for the first time ever, euphoric cheers erupted in SpaceX’s mission control center in California. Dragon was in orbit, and it was a thrill ride from start to finish.

Over the next few hours, Dragon completed a set of critical on-orbit checkout activities, and achieved the critical step of opening its Guidance, Navigation and Control (GNC) bay door, exposing its rendezvous sensors and grapple fixture to space – another first time operation. Thruster checkouts and free-drift checkouts were also conducted.

Two days after launch, on 24 May, and after a series of successful rendezvous burns comprising the C2 portion of the mission, Dragon passed below the ISS at a safe distance, in order to give NASA confidence that Dragon could perform its required navigation and rendezvous tasks, while avoiding placing the ISS in any danger should they have failed. With all objectives passed, the Go was given for the “big one” – the rendezvous, capture, and berthing with the ISS.

The date was 25 May 2012 – less than one year since the retirement of the Space Shuttle – when Dragon finally, step-by-step, flew its way to 30 meters below the ISS, under the watchful eye of SpaceX flight controllers, who exhibited the same cool, calm professionalism as was seen during Shuttle dockings to the station.

With the crew of Expedition 31 aboard the ISS manoeuvring the Space Station Remote Manipulator System (SSRMS), Dragon was finally captured by the tail, thus demonstrating for the first time ever that a commercially-built vehicle can reach the ISS.

Once Dragon was berthed to the ISS and the hatches opened, five days of cargo unloading activities commenced, which also included the loading of cargo back into Dragon from the ISS for return to Earth, i.e. “downmass” – a critical capability lost with the retirement of the Shuttle fleet.

On 31 May, Dragon was unberthed from the ISS and released to fly free once more, followed the same day by the closure of the GNC bay door – yet another first demonstration of a small but critical step – whereupon the de-orbit burn was conducted, followed shortly thereafter by Trunk umbilical disconnection and Trunk separation.

Dragon then re-entered the atmosphere for its second time in history, having been previously done on the C1 flight in December 2010, following which the three parachutes of Dragon were deployed in order to allow it to make a safe splashdown in the Pacific Ocean off the coast of California.

As images of a charred – but intact Dragon – gently bobbing in the ocean began to surface, it was clear that the era of commercial resupply was here – with the “era of no downmass” having lasted only ten months.

And Dragon was back for more action in October of 2012, as SpaceX performed the first flight under the Commercial Resupply Services (CRS) contract with NASA – on the mission tagged SpX-1 (CRS-1).

While the mission to resupply the ISS and return critical cargo that had been amassing aboard the ISS since the last Shuttle flight was a success, the CRS-1 mission was not without incident – namely an in-flight “Rapid Unplanned Disassembly” of one of the Falcon 9 booster’s first stage Merlin-1C engines.

While the capability of SpaceX to reach the ISS and perform their contractual objectives to NASA was most certainly proven in 2012, the challenge for SpaceX in 2013 will be to maintain that success rate, while ensuring no further anomalies occur.

The rapid increase in flight rates – when coupled with missions also scheduled to be performed for non-NASA customers – will be the true test of whether SpaceX is up to the challenge of supporting the ISS in the post-Shuttle era.

From a logistic standpoint, the ISS is in great shape heading into 2013, with the two successful SpaceX flights, and successful flights by the ATV and HTV vehicles all occurring in 2012.

(ATV-3 Docking Animation created from 70 hi res ATV-3 docking images acquired by L2 – LINK).

While Orbital’s Cygnus spacecraft never made it to the ISS in 2012, ISS logistics remained unaffected, due to the smart decision to stockpile the ISS with logistics during the final Space Shuttle flight. If the momentum built up in 2012 can be maintained, ISS logistics look good for 2013 and beyond.

Also aiding logistics, and crewed flights, was the fact that the Russian Soyuz booster suffered from no failures in 2012, after a number of events in 2011 – notably the loss of the Progress M-12M cargo vessel in August 2011.

The problems of the Russian space industry unfortunately still persist however, with a number of failures of upper stages of Proton boosters occurring in 2012. However, as before, if the current trend continues, 2013 looks good from a station crewing standpoint, although a close eye will still be needed to ensure no further failures of Soyuz boosters occur.

In addition to the successes in logistics and crewing, 2012 also proved another vital capability for the ISS in the post-Shuttle era, although not exactly in a planned way: The ability of the ISS to “hold its own” in a fight against external hardware failures, without the support of the Space Shuttle.

In the Shuttle era, external tasks on the station had been performed by Space Shuttle Extra Vehicular Activity (EVA) crews, who trained for those specific EVA tasks prior to launch, thus saving the ISS crew from having to conduct spacewalks.

In addition, the Shuttle provided the vital capability to launch and return external hardware to/from the ISS. However, with the Shuttle now gone, those tasks would have to be shouldered by the ISS crew alone, with the vital lifeline of EVA support via the Shuttle cut off.

The date was 30 August, 2012. It was supposed to be a simple task – swap out a failing Main Bus Switching Unit (MBSU) power distribution box with a spare unit already outside the ISS. It was a fairly routine operation, to be performed by spacewalkers Suni Williams and Aki Hoshide, in a six hour excursion that also included a number of other routine tasks outside the station.

The problem: The MBSU just didn’t want to co-operate. After successfully removing the failing MBSU from its housing on the S0 Truss, the new MBSU proved extremely difficult to bolt in place of the old unit.

The design of the MBSU – as with many other ISS components – is such that the electrical connections are only made once the unit is fully seated on its baseplate, with full seating being achieved via the full driving of two bolts.

Thus, if the bolts don’t drive, the MBSU remains disconnected, unable to perform its duty.

After a gruelling eight-plus hour EVA, during which everything was tried to get the MBSU to bolt down in place – including adjusting its angle to the baseplate, wiggling it around with the bolt partly driven, clearing out the bolt socket of metallic filings, and pure brute force via the use of torque multipliers, the stubborn MBSU’s bolts just could not be driven.

The led to the exhausted pair of Williams and Hoshide having to re-enter the ISS, with the MBSU remaining uninstalled. Another attempt would have to be made.

With the MBSU disconnected, 25 per cent of the station’s power was lost, as the MBSU could not do its job of distributing two of the station’s eight power channels to their respective loads.

However, as if the situation wasn’t bad enough, a Direct Current Switching Unit (DCSU) on the P6 Truss tripped, taking a further 12.5 per cent of the station’s power with it.

With the ISS running on less than two thirds of its normal power – and no “super Shuttle” to call upon to save the day – the station would need to fight its own corner in the battle against electrical adversity.

Fortunately, the station is well equipped, and is looked after by some very smart people both aboard and on the ground.

A plan was hatched to re-attempt to bolt the troublesome MBSU in place, which involved the ISS crew building their own specialist tools from parts scavenged from various parts of the station. During the second EVA, the planning worked, and the MBSU was finally bolted into place to resume its power distribution duties.

The cause of the stuck bolts was likely debris in their baseplate sockets – caused itself by the fact that the previous MBSU had been in place for ten years, and had never been removed on-orbit, and thus was slightly stiff during removal, causing abrasion between its bolts and the sockets.

The ISS and its crew had proven that when the chips were down, it could, using its own resources, solve the problem unsupported by the Shuttle.

Less than two months later – and with the tripped DCSU problem successfully resolved without the need for an EVA – another problem was found on the outside of the ISS: A growing ammonia leak in a cooling radiator on the P6 Truss.

While the leak had been known about for years – and had been topped up with ammonia during the penultimate Shuttle flight – the rate had dramatically increased in the second half of 2012, requiring imminent action in order to prevent the loss of a power channel due to insufficient coolant.

The ammonia leak was traced to a set of cooling lines in a radiator on the P6 Truss.

Once again, the ISS had to turn to itself to solve the problem – and luckily, due to its intelligent design, the facilities existed to solve the problem in the form of a disused cooling radiator from the early years of the ISS program.

The plan was to deploy this old radiator, disconnect the cooling lines from the leaking radiator, and connect them to the newly deployed radiator – thus disconnecting the leaking radiator loop, halting the loss of further coolant.

Even though the by now seasoned pair of Williams and Hoshide had received no pre-flight training for the task, the EVA went off without a hitch, and while the outcome of the leak is still unknown, the spacewalk was definitely yet another demonstration that the ISS can “survive on its own” against hardware failures, due to its intelligent design, good stockpile of spare parts, and resourceful supporting crews.

The ISS also continued throughout 2012 to average its promised 35 hours per week of science activities – a tough task considering that all maintenance now needs to be carried out by ISS crews instead of Shuttle crews.

While the results of this scientific surge on the ISS will not be seen for a few years, it is proof that the ISS is finally doing what it was designed to do: Serve as a platform for research to benefit Earth and further space exploration.

All in all, 2012 was a very good year for the ISS, when the station demonstrated its ability to survive on its own, deal with problems and failures, and still function and operate successfully, while also ushering in many new capabilities that will see it through the rest of the decade.

It is on the back of these successes that the ISS is set to sail into 2013, a year that looks set to be equally as exciting as the last.

2013 on the ISS:

If 2012 was the year for SpaceX, then 2013 will be the year for Orbital Sciences Corporation – specifically their Antares rocket and Cygnus freighter, which are set to debut next year after being pushed back from 2012.

The year promises much excitement as Orbital conduct their first hot-fire test of Antares, first test launch of Antares, and finally a full cargo demonstration mission to the ISS with the Cygnus vehicle – hopefully ushering in another vehicle capable of supporting the station in the post-Shuttle era.

According to a recent ISS Flight Planning Integration Panel (FPIP) chart – previously known as the Flight Planning Working Group (FPWG) chart – which shows the ISS flight schedule all the way out to 2018 (available to download on L2), Orbital are also scheduled to conduct at least one CRS flight in 2013, although this will depend on the outcome of the aforementioned test flights.

One ATV and one HTV flight are also planned for 2013, as well as two SpaceX Dragon flights, in addition to the usual stream of Russian Progress flights.

2013 will also see the first time that a Soyuz spacecraft performs a six-hour rendezvous and docking to the ISS, another useful capability for the station in the post-Shuttle era.

Looking toward the end of 2013, the long-awaited Russian Multipurpose Laboratory Module (MLM) is planned to launch in December, although rumours have circulated that the launch may slip to early 2014, with Russian officials dismissing these rumours by saying that the MLM will launch in December 2013, even if it launches empty due to internal hardware not being ready.

Whether the December 2013 launch date will hold, however, remains to be seen.

2013 also promises to be another good year from a research and technology demonstration standpoint, with the first ever simulated satellite refuelling in space set to kick off in mid-January via the Robotic Refuelling Mission (RRM) experiment.

A number of other interesting experiments will also be performed on the ISS in 2013, including the launch of a talking humanoid robot for the Japanese segment of the station, having astronauts control rovers on Earth from the ISS, and implementing time delays into ISS communications in order to simulate Mars mission planning.

Post-2013 on the ISS:

Looking further ahead into the future, many interesting events lie ahead for the ISS, including the arrival of two brand new, modern Russian science modules – the contract for the construction of the first of which has recently been awarded to RSC Energia Corporation.

A modernised Progress-MS spacecraft is set to debut in 2014, followed by the modernised Soyuz-MS series of spacecraft, in preparation for a planned 2017 debut of the new Russian Advanced Crew Transportation System (ACTS) spacecraft.

Set to be demonstrated in late 2016 is the first US Crew Vehicle (USCV), built by the winner(s) of the commercial crew spacecraft competition. The FPIP charts (L2) provides some interesting information on the plan for ISS crew rotations using the USCVs, although the details must be taken as preliminary at this point.

According to the FPIP chart, the first USCV will launch in December 2016, for a docking to the Node 2 Forward port – via the use of an ISS Docking Adapter (IDA) attached to PMA-2. A Soyuz spacecraft is also pencilled in for the same date as a back-up (all USCVs on the chart have Soyuz back-ups assigned, should the USCV not be available).

The USCV will carry four crewmembers, meaning that once it docks to the ISS, the crew of the station will be boosted to seven – allowing significant extra research activities to be performed. However, one of the crewmembers on the USCV will be Russian – just as one American crewmember will continue to be rotated on the Soyuz.

This is done in order to ensure that a US crewmember is always present on the ISS, even when no USCV is docked to the station. It is not known at this point whether the seat on the USCV will be provided to Russia in exchange for a US seat on the Soyuz.

Crew rotations using the USCVs will be done using the indirect handover method – meaning one USCV will return to Earth with its four crewmembers after six months on-orbit, prior to another USCV launching with another four crewmembers for another six month stay.

This means only one USCV will ever be docked to the ISS at any one time, and will make for two USCV fights to the ISS per year. However, if the one year ISS Expeditions are successful and become a permanent arrangement, this will likely reduce to just one USCV flight per year.

While the above milestones seem a long way off at this moment, they show that there are many exciting events to look forward to on the ISS in the coming years, as the station starts to show the world what it can do as a fully operational, self-supporting space laboratory, contributing to improvements in life on Earth, and vital capabilities for future space exploration.

To the ISS, we wish you a lucky 2013.

(Images: via L2’s ISS and SpaceX Special Sections – Containing presentations, videos, images, space industry member discussion and more. Includes the entire COTS 2+ and CRS-1 Image Dump – every single hi res photo (700+) taken from the ISS).

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