Major Overhaul – Replacing the Ammonia Pump Module on the ISS

August was a busy month for the crew of the International Space Station and the support teams on the ground. On Saturday, 31 July 2010 the Loop A Ammonia Pump Module (pictured at right) on the External Thermal Control System (ETCS – pdf) on the S-1 truss on the Integrated Truss Structure (Starboard side – diagram below) failed, cutting the main cooling capacity of the United States portion of the International Space Station by 50%. The Russian modules have their own cooling system. Station managers began shutting down a variety of systems and experiments on board the ISS in order to reduce the heat load to a level manageable by the Loop B ETCS on the P-1 truss (Port side). Two EVAs were scheduled to remove and replace (R&R) the Pump Module. The first for Thursday 5 August and the second no earlier than two days later.

Ammonia Pump Module Flown on STS-129 Image Credit: NASA

Image from the Interactive Guide to the Integrated Truss Structure
Image Credit: NASA

Planning for the first EVA eventually caused the spacewalk to slip to Saturday. The EVA tasks required working with numerous electrical cables and both internal and external cooling fluid lines prior to being able to remove the Ammonia Pump. The first EVA was scheduled to disconnect cooling lines and remove the failed pump module from the S-1 truss. Problems were encountered with one of the quick disconnect units on an ammonia line, and removal of the pump module was postponed until the second EVA. Doug Wheelock and Tracy Caldwell-Dyson began the second EVA at 7:27am Central time (9:27 EDT) on Wednesday 11 August. This time the quick disconnects for cooling and electrical connections went as planned. The two astronauts then successfully removed the failed pump module and stowed it.

Ammonia Pump Module Diagram Image Credit: forum.nasaspaceflight.com

External Thermal Control System Truss Diagram Image Credit: forum.nasaspaceflight.com

The third EVA began on Monday 16 August at 5:20am Central Time. Astronauts Doug Wheelock and Tracy Caldwell-Dyson then set out to unbolt the replacement Pump Module (PM) and place it in position on the S-1 Truss. Wheelock removed the bolts holding the new PM to ESP-2 (External Stowage Platform) and the Space Station Remote Manipulator System (SSRMS) then translated Wheelock and the 780 pound PM to the S-1 truss. Wheelock bolted the PM into place and Caldwell-Dyson mated several electrical connections, “waking up” the PM. Initial electrical testing prove the new PM was ready to go. Various fluid lines were reconnected and ammonia was reintroduced into the system. By Wednesday 18 August, the International Space Station was beginning to get back to normal. There were no yellow or red system lights on the status board. On Wednesday and Thursday, the major effort involved bringing the Columbus science module and the Japanese Experiment Module (JEM – “Kibo”) back online. The remainder of the month has involved bringing the various experiments back on line and testing the coolant systems in Loop A. Congratulations to the ISS team for successfully working the Pump Module failure. With three additional back up PMs on the Space Station, we can expect to see this scenario repeated. Lessons Learned will be carried forward by the ISS team. Current expectations are that the ISS will be in operation until 2020, and perhaps beyond that. There will be a lot more R&R of various systems as the years pass.

Let us know what you think. What do you want to know about? Post a comment.

Endeavour – STS-130 – Tranquility Ammonia Coolant Line Failures – Update

Special thanks to Larry Sullivan for these high resolution images of the Endeavor Rollout Image Credit: NASASpaceflight.com photos by Larry Sullivan

As note previously in the Endeavour Rollout post, the Active Thermal Control System (ATCS) on the Tranquility node from the European Space Agency (ESA) has experienced a number of failures in the ammonia lines that threaten to derail the 7 February launch. Yesterday, Chris Bergen at NASASpaceFlight.com reported on the ruptures and the three courses of action being worked to resolve the issue: Launch Tranquility as scheduled without the ammonia lines. Attach Tranquility and activate it during a later mission later when certified lines are ready. Delay the launch until the problem is resolved. Fly the STS-131 19A mission before STS-130 20A mission However, as previously noted, the relocation of mission racks causes serious problems for the third option. Chris Bergen notes that options 1 and 2 are being worked the hardest.

Later in the day, reports surfaced about the “tiger team” focusing on two solutions. The first is “A redesign of the original lines using double braid… A 7′ line with the double braid failed at a PSI > 5000 which is a good sign,” noted ISS Flight Director Robert Dempsey. The second is what Mr. Dempsey referred to as “…the franken hose – they have pulled out a bunch of smaller hoses from KSC that have already past cert qual and welding them together. The 14′ hoses we need would be a welding of 3-5 pieces.” Nobody is particularly interested in trying to swap STS-130 and STS-131 missions, as that would impact the flight schedule through the end of 2010 and likely into 2011, along with any added missions using the one existing External Tank not currently scheduled, along with two other possible tanks. The most likely scenario at the moment is a delay of as much as two months in flying STS-130 in order to resolve the ammonia line issue. 27 January Update: Chris Bergen, at NASASpaceFlight reports that NASA’s Flight Readiness Review (FRR) has concluded that Endeavour will make its first launch attempt as scheduled on 7 February 2010. The FRR notes: “The ISS team is making great progress on the ammonia hoses. Two different designs are being assembled/manufactured in parallel. The prime hoses (Titeflex hoses) have been welded and the inspections should be complete on 1/22 and crew fit checked on 1/23,” noted MOD’s 8th Floor (L2). “The backup hoses (FMH) have been successfully proof tested and delivered to MSFC (Marshall Space Flight Center). No technical or schedule issues are anticipated.”

If you have ever wondered how they transfer Liquid Oxygen and Liquid Hydrogen from the External Tank to the three rocket engines on the Endeavour, examine this close up by Larry Sullivan. Image Credit: NASASpaceflight.com photos by Larry Sullivan

NASA – ISS Science Success – Part I

Part I, Part II, Part III

International Space Station. Credit: NASA Image

It now appears likely that the mission of the International Space Station (ISS) will be continued through 2020 (See the Augustine Scenarios). And following NASA’s announcement in September of the release of the report on “International Space Station Science Research Accomplishments During the Assembly Years: An Analysis of Results from 2000-2008”, now would be a good time to look back on the scientific accomplishments so far, and to look ahead. Because NASA’s report is 250 pages in length, we will digest it in small pieces. The major areas of research include: Technology Development for Exploration Physical Sciences in Microgravity Biological Sciences in Microgravity Human Research Program Observing the Earth and Educational Activities Science from International Space Station Observations

Following launch of the Russian Zarya module in 1998, and before human occupation began in 2000, several experiments were conducted:

• Protein Crystal Growth – Enhanced Gaseous Nitrogen Dewar (PCG-EGN)
• Commercial Generic Bioprocessing Apparatus: Kidney Cell Gene Expression (CGBA-KCGE) and Synaptogenesis in Microgravity (CGBA-SM)
• Incidence of Latent Virus Shedding During Space Flight (Latent Virus)
• International Space Station Acoustics Measurement Program (ISS Acoustics)

One of the most exciting results reported from ISS research is the confirmation that common pathogens change and become more virulent during space flight, performed in September 2006. This has important implications for extended human missions. It is also a target for additional research.

During the time covered by this report, steady growth in publications associated with ISS research has occurred, as shown in the graph to the right. What have been the major research results in each of the six areas discussed in the report? Technology Development for Exploration One of the most important concerns of any space based operation has to be air quality. Therefore, the experiments with the “Analyzing Interferometer for Ambient Air” (ANITA) instrument will prove crucial to future explorers. “ANITA was calibrated to simultaneously monitor 32 gaseous contaminants (including formaldehyde, ammonia, and carbon monoxide (CO)) at low as parts per million levels in the ISS atmosphere. The hardware design—a quasi on-line, fast-time resolution gas analyzer—allowed air quality to be analyzed in near real time.”

Credit: NASA Image

As an example of the importance of these capabilities, the report notes that “ANITA was used in mid 2008 to detect a Freon leak (Khladon 218) from the Russian air conditioner, and to monitor the timeline of Freon concentrations with CDRA operations and shuttle docking. The ANITA data helped to determine that the zeolite bed in the CDRA was not effective in scrubbing the Freon leak, but that diluting the ISS air after the docking with the shuttle substantially reduced the level of Freon” (p18).

Other research topics include:

• The Active Rack Isolation System (ARIS), which protects equipment by absorbing the shock of motion before it can affect an experiment.
• The Smoke and Aerosol Measurement Experiment (SAME), which is planned to gather particulate size information on ISS. It is known that fires in microgravity produce smoke particles that are larger than on Earth. Being able to distinguish between smoke and other particles on ISS is important.
• “The elastic memory composite hinge (EMCH) experiment provided test data on new materials that will further space hardware technology. This technology may eliminate the need for highly complex deployment mechanisms by providing a simpler, lightweight alternative to mechanical hinges. EMCH builds on the previous space shuttle experiment, lightweight flexible solar array hinge (LFSAH) that was flown on STS-93” (p 22).
• “The In-SPACE Soldering Experiment (ISSI) is another payload that was rapidly developed after the Columbia accident to provide a lowmass experiment using hardware already on board station. It was designed to promote understanding of joining techniques, shape equilibrium, wetting phenomena, and micro-structural development in space” (p 23).

Physical Sciences in Microgravity

While Technological Development is important for space exploration, pure research also has a place on the ISS. Protein crystal growth, fluid physics and materials science are being researched:

• The Advanced Protein Crystallization Facility (APCF) can support three crystal-growth methods: liquid-liquid diffusion, vapor diffusion, and dialysis. In the vapor diffusion method, a crystal forms in a protein solution as a precipitant draws moisture in a surrounding reservoir. In the dialysis method, salt draws moisture away from the protein solution via a membrane separating the two and forming crystals. Initial analysis of the crystals that were returned from station supports the findings of earlier APCF flights: comparative crystallographic analysis indicates that space-grown crystals are superior in every way to control-group crystals that are grown on Earth under identical conditions (p 47).
• The Binary Colloidal Alloy Test hardware supported “three investigations in which ISS crews photographed samples of colloidal particles (tiny nanoscale spheres suspended in liquid) to document liquid/gas phase changes, growth of binary crystals, and the formation of colloidal crystals that were confined to a surface. Colloids are small enough that in a microgravity environment without sedimentation and convection, they behave much as atoms. By controlling aspects of colloidal mixtures, they can be used to model all sorts of phenomena” (p 49).
• Protein Crystal Growth-Enhanced Gaseous Nitrogen (PCG-EGN) was designed to produce crystals of various biological compunds. Also, some 500 student preparations were made as part of an education program to teach students about crystallization, crystallography methods and the impact of crystallography on medicine and biotechnology. A significant number of crystallization were successful. Indeed, some of the results produced better data than could be obtained in Earth bound efforts (p 69).

Sometimes, “no” is just as important as “yes”.

Researchers have found that it is possible to grow high-quality protein crystals in the weightlessness of LEO, where gravitational forces will not distort or destroy a crystal’s delicate structure.

The goal of the Dynamically Controlled Protein Crystal Growth (DCPCG) experiment was to control and improve the crystallization process by dynamically controlling the elements that influence crystal growth.

DCPCG was the first flight test of an apparatus that was designed to control the crystal growth process by controlling the rate of evaporation. The apparatus worked on orbit, and crystals were grown for the test proteins; however, the investigators determined that the growth could have been better. The same apparatus was used in extensive testing on the ground. Researchers tested a selection of protein solutions, including insulin (a hormone that is produced by the pancreas to regulate the metabolism and use of sugar), serum albumin, and lysozyme (an enzyme that attacks bacteria) and found that a slower evaporation rate yielded better results than a more rapid evaporation rate. While the results of the ground tests were published, the DCPCG experiment investigators did not seek to publish any structures from crystals grown in orbit.

What’s Ahead

In 2008, the European Space Agency’s (ESA’s) Columbus and Japanese Aerospace Exploration Agency’s Kibo scientific modules joining NASA’s Destiny Laboratory. Further, in 2009, the number of crew members increased from three to six. This means that a lot more time is available for research in the future.

New experiments aboard the ISS include a broad range of science, as follows:

• Coordinated human research experiments that collaborate with International Partners’ science objectives and activities, including shared baseline data collection and in-flight sampling, with the goal of understanding integrated causes and effects of changes in the human body.
• Research using new science racks, including the fluids integrated rack (FIR), the combustion integrated rack (CIR), and materials science research rack (MSRR), will enable new experiments exploring combustion, fluid behavior, and heat-dependent crystallization patterns in metal alloys.
• Exploration Technology Development will build from early experiments on materials exposure, smoke generation, liquid fuel management, and environmental monitoring.
• The new Window Observation Research Facility (WORF) will provide capabilities to support remote sensing instruments, enabling Earth Science research that will, for example, document crop health and test the utility of blue-green bands for ocean research.

Part I, Part II, Part III