June 14, 2020 by Sam Holland
On 30/5/20, NASA astronauts Doug Hurley and Bob Behnken proudly docked the International Space Station (ISS).
Such success, however, followed a postponed launch date due to adverse weather just three days prior. We revisit the events and consider why the initial launch date posed such a significant risk.
The successful launch from the Kennedy Space Center (KSC), Florida, and the docking of SpaceX’s Dragon capsule on the ISS followed NASA’s $3.1B investment in Elon Musk’s SpaceX programme.
This is in accord with the former’s Commercial Crew Program, which has been defined as a collaboration with the American aerospace industry to “develop and operate a new generation of spacecraft and launch systems [to] carry crews to low-Earth orbit and the ISS”. (Click here to read up on the technological implications of a commercialised space industry.)
But while the Dragon capsule (commonly known as Capsule 206 but later named ‘Endeavour’ by the astronauts) and its mission (i.e. SpaceX Demonstration Mission 2) was indeed partly NASA-funded, the successful SpaceX programme nevertheless remains a world first: never before has a spacecraft owned by a private company shuttled human occupants into orbit.
In fact, until this launch had occurred, there had not been one manned launch from U.S. soil since 2011, when NASA ended its 30-year Space Shuttle Program. Again, however, the launch was not successful the first time around. Before ultimately considering why this initial postponement occurred, let’s now recap the chain of events that occurred last month.
SpaceX and NASA’s initial plan was for Wednesday, the 27th of May to see the two ex-military astronauts launch Falcon 9 (the rocket behind the lift-off of the Crew Dragon capsule) from the KSC.
However, the atmospheric conditions that Wednesday had, to quote NASA administrator Jim Bridenstine, “simply too much electricity”. And this was to the point that, as will be discussed below, the flight of the spacecraft could have triggered lightning (a phenomenon often named ‘launch-triggered lightning’).
In response, SpaceX moved the launch date to Saturday the 30th of May, and at 15:22 EDT (19:22 GMT), the by-then safer atmospheric conditions meant that the lift-off was successful. Following the launch, Capsule 206, aka Endeavour, continued its flight having detached from its Falcon 9 rocket. (That same day at around 20:30, the disconnected Falcon 9 booster, which—in stark contrast to an expendable launch vehicle—is reusable, landed safely on SpaceX’s Atlantic ocean-based autonomous spaceport drone ship: ‘Of Course I Still Love You’.)
Astronauts Doug Hurley and Bob Behnken stand proudly in front of their Dragon spacecraft capsule. Image Credit: Flickr.
By the next morning, namely Sunday, 10:16 EDT (14:16 GMT), Behnken and Hurley docked the International Space Station, thereby joining NASA astronaut Chris Cassidy, the commander of Expedition 63 (Exp 63)—the ISS’s physical sciences and technological research project into low-Earth orbit and both moon and mars travel—alongside Exp 63’s two Russian cosmonauts: flight engineers Anatoly Ivanishin and Ivan Vagner.
Referring to what will forever be “the first commercially built and operated American spacecraft”, NASA stated that the successful launch and docking of the spacecraft has introduced “a new era in space flight”.
The game-changing event follows the space agency’s plans to use its said Commercial Crew Program: a collaboration with SpaceX, and also Boeing, in the interest of designing, building, testing, and operating “safe, reliable and cost-effective human transportation systems to low-Earth orbit”. (Click here to read up on the electronics systems involved in Falcon 9.)
Again, SpaceX and NASA’s decision to delay the flight of the Falcon 9 rocket and its capsule and crew was based on the high amount of electricity in the atmosphere on Wednesday, the 27th of May, following a tornado warning that occurred just hours before the launch was arranged. Below, we look at just how necessary this decision was, particularly based on NASA’s previous challenges in the face of electrified clouds.
Left to right: Bob Behnken and Doug Hurley sit in a NASA cockpit to test their spaceflight hardware. Image Credit: SpaceX.
The decision to cancel Wednesday, the 27th of May’s launch was far from an overly cautious consideration for Behnken and Hurley’s safety. In fact, NASA had already seen two launch-triggered lightning strikes almost destroy the Apollo 12 mission as far back as 1969 (overloaded, the spacecraft’s primary power went offline, leaving the astronauts to resolve the threat with only the backup systems left active).
While nail-biting (and surprisingly overlooked compared to the more publicised events of Apollo 11 and 13), the Apollo 12 mission led to the industry’s much better understanding of launch-triggered lightning (LTL) strikes. As NASA’s report observed, in an electric field, “lightning can be triggered by the … long electrical length created by the space vehicle and its exhaust plume, … which would not otherwise have produced natural lightning”.
This is as a spacecraft’s ionised exhaust plume (dictionary-defined as ‘a long cloud of smoke or vapor, resembling a feather as it spreads from its point of origin’) adds to the already-high electrical conductivity of the vehicle itself. And in fact, such conductivity also lessens the electrical field strength required to trigger lightning in the first place, so a significant risk applies even when the clouds contain only a moderate electrical field.
As John Madura, manager of KSC’s Weather Office states in NASA’s Educational Features page: “The lightning is triggered by the vehicle passing through the moderate electrical field in clouds of sufficient thickness near the freezing level”.
Clearly, then, the dangers of electrified clouds had to be avoided on Wednesday, the 27th of May. For decades, and to this day, electrified clouds remain just one of the many factors that NASA’s Lightning Advisory Panel (LAP)—which was formed in response to an LTL strike destroying NASA’s unmanned Atlas-Centaur rocket in 1987—has to take into strict consideration when deciding upon launch dates. (More information can be learned by reading LAP’s Lightning Launch Commit Criteria.)
An example of a SpaceX Falcon 9 rocket in flight, which is followed by an enormous engine plume. Image Credit: Vandenberg Air Force Base.
Of course, while SpaceX’s delayed launch date on the 27th of March draws on a decades-old history of the risks of electrical weather conditions in spaceflight, the commercial flight has since proved a historic success, following improved weather conditions just three days after the postponement.
The implications of the event are that aerospace is now set to become a far more commercialised industry, and at the time of writing, astronauts Bob Behnken and Doug Hurley (who may return to Earth in August 2020) have since settled into, not only the International Space Center itself, but also their overall roles within Expedition 63—marking a breakthrough in both private spaceflight (aka ‘New Space’) and international cooperation.
Said Behnken: “The message, for us, is one of cooperation and understanding … [T]he International Space Station has provided a place for many countries to cooperate and integrate and successfully accomplish science—accomplish the mission of human spaceflight”.
