Dragon CRS-18 Arrives with Crew Docking Adaptor, Raft of Science for Space Station

NASA astronauts Nick Hague (center) Christina Koch (left) and Drew Morgan (right), currently serving with the Expedition 60 crew on the International Space Station, welcome SpaceX Dragon CRS-18 to the orbiting outpost on 27 July 2019. Photo Credit: NASA

SpaceX successfully delivered their 18th resupply mission to the International Space Station today, bringing with it more than 5,000 pounds of research, supplies and hardware for the orbiting laboratory and the six-member Expedition 60 crew currently serving onboard.

Launched two days ago from Cape Canaveral, Fla., the Cargo Dragon is flying on its third mission (also launched on a reused rocket), and was welcomed to the ISS by NASA astronauts Nick Hague and Christina Koch, who together grappled the spacecraft at 9:11 a.m. EDT using the space station’s robotic arm Canadarm2, while cruising 17,500 mph over southern Chile at an altitude of about 260 miles.

Dragon CRS-18 captured by the space station’s robotic Canadarm2. Photo Credit: NASA

Ground controllers then sent commands to begin the robotic installation of the spacecraft to the bottom of the station’s Harmony module, where it will now stay for about a month before returning to Earth.

As detailed in our CRS-18 preview by Ben Evans, primary payload onboard Dragon is the second International Docking Adapter, numerically designated “IDA-3”, which will provide a secondary port at the space station for visiting Commercial Crew vehicles.

SpaceX recently flew a successful orbital flight test to and from the ISS (Demo 1) with their Crew Dragon, and hopes to fly their first crewed orbital flight test (Demo 2) there and back in the next 6 months, along with Boeing’s first uncrewed orbital flight test with their Starliner capsule (Orbital Flight Test 1).

CRS-18 launch. Credit: Jeff Seibert / AmericaSpace.com

Original plans called for two Boeing-built IDAs—with IDA-1 sitting at the forward end of the Harmony node and IDA-2 on its space-facing (or “zenith”) port—but in June 2015 IDA-1 was lost during the CRS-7 launch failure. A year later, in July 2016, IDA-2 successfully reached orbit and was attached to the forward end of Harmony a few weeks later by Expedition 48 spacewalkers Jeff Williams and Kate Rubins, thereby taking up the role of the original IDA-1.

In February 2016, NASA and Boeing finalized a $9 million contract to build and test a replacement IDA in the Space Station Processing Facility (SSPF) at the Kennedy Space Center (KSC) in Florida. IDA-3 arose from around 300 extant ground spares (representing about 70 percent of the whole), with original hopes that it may launch as soon as the spring or fall of 2017, but this date was pushed back several times as the Commercial Crew Program (CCP) suffered extensive delays and key ISS science payloads—including the Global Ecosystem Dynamics Investigation lidar (GEDI)—took priority.

Like IDA-2, the new IDA-3 is fully compliant with the International Docking System Standard (IDSS), an effort by the ISS Multilateral Co-ordination Board to create an international spacecraft docking standard for the U.S. Operational Segment (USOS). “Connecting spacecraft from different nations has required unique development and expensive integration and test,” NASA Headquarters conference notes from April 2011 explained.

The 1,150-pound (520-kilogram) IDA-3 will sit atop Pressurized Mating Adapter (PMA)-3, which was relocated from the station’s Tranquility node to Harmony’s zenith port via a ballet of spacewalking and ISS robotics, back in March 2017. The new docking port will effectively convert PMA-3 from its original Androgynous Peripheral Attach System (APAS)-95 specification to Boeing’s new Soft Impact Mating and Attenuation Concept (SIMAC), which NASA accepted in late 2012 to satisfy its Commercial Crew requirements and replace earlier plans for an international Low-Impact Docking System (iLIDS).

According to NASA, Hague and fellow astronaut Andrew Morgan will conduct a spacewalk in mid-August to install the docking port, connect power and data cables, and set up a high-definition camera on a boom arm. Robotics flight control teams from NASA and the Canadian Space Agency will move the docking port into position remotely before the astronauts perform the final installation.

Also aboard CRS-18 are a raft of critical science payloads for the ISS itself. The Biorock investigation, provided by the University of Edinburgh in the United Kingdom, will explore the interactions between microbes and rocks in a liquid phase and how they are affected by the reduced-gravity conditions in low-Earth orbit. Specifically, low levels of thermal convection are known to minimize the natural stirring in liquids and gases and may restrict the supply of food and oxygen to bacteria, thereby hampering their growth.

It is expected that data from Biorock will provide insights into bacterial/rock interactions both on Earth, in microgravity conditions and in the one-third-gravity environment on Mars. This is expected to prove beneficial when devising life-support systems with microbial components for long-term deep-space missions and for space mining applications in support of lunar or Martian bases and eventual colonies.

The Space Tango-Induced Pluripotent Stem Cells experiment seeks to examine how microglial cells—a type of immense defense cell, found in the central nervous system—grow, move and change in the microgravity environment. Data from this investigation may offer valuable insights into characterizing, understanding and devising therapies for conditions such as Parkinson’s disease and multiple schlerosis. More broadly, understanding nerve-cell growth and survival, together with changes in gene expression in space, are expected to yield clues about how best to protect astronauts on longer missions into deep space.

CRS-18 launch from the roof of NASA’s iconic Vehicle Assembly Building. Credit: Alan Walters / AmericaSpace.com

The BioFabrication Facility (BFF) will seek to 3D-print, for the first time, organ-like tissues in microgravity, as a stepping-stone toward long-term plans to manufacture whole human organs in space with refined biological 3D-printing technologies. NASA’s Cell Science-02 experiment will gain further information on the practicalities of carrying out bone-fracture repair/regeneration programs on future missions, whilst the MVP Cell-02 investigation will utilize NASA’s Multi-Use Variable-g Platform—launched to the station aboard the CRS-14 Dragon in April 2018—to understand the evolution and adaptability of the fast-growing Bacillus subtilis bacterium to microgravity conditions. Its core characteristic of rapid growth will allow it to be observed through many generations over a matter of just a few weeks on-orbit.

  • Written by Ben Evans and Mike Killian



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