After being delayed by weather earlier this week, NASA and SpaceX made history on Saturday.
The Crew Dragon spacecraft successfully lifted off from Launch Complex 39A, at Kennedy Space Center, at 3:22 p.m. EDT on May 30, 2020. This is the first time astronauts have launched from the United States in nearly nine years, and it is now the very first commercial spaceflight mission to launch humans into orbit.
“We are so proud and happy for Doug and Bob,” astronaut Nicole Mann, who is slated to fly on a future commercial launch on Boeing’s Starliner spacecraft, said in a NASA statement earlier this week. “It feels kind of like one of your close family members having a great lifetime achievement — and really, that’s what it is.”
After the launch, the Falcon 9 booster completed its journey to orbit, carrying Behnken and Hurley onboard Crew Dragon, in just under 9 minutes. By the time the astronauts got to experience the weightlessness of being in orbit, the 1st stage of the Falcon 9 rocket was already setting down on the droneship “Of Course I Still Love You”, out on the Atlantic Ocean.
Now, as Crew Dragon makes its way towards the International Space Station, set to arrive at 10:29 a.m. Sunday, May 31, this Falcon 9 booster will be brought back to shore. It will either go on to launch other missions – crewed or uncrewed – into space, or SpaceX may turn it into a monument, as they did with the first booster that they successfully landed at Cape Canaveral.
WEATHER OR NOT
The final updated weather forecast from the U.S. Air Force’s 45th Weather Squadron, as of Saturday afternoon, gave a 70 per cent chance of favourable conditions for the Demo-2 launch attempt. The primary weather concerns given were the potential for cumulus or anvil (cumulonimbus) clouds in the vicinity of the launch site, and the possibility of the rocket flying through precipitation. All of those conditions cleared in the area as of around 2:30 p.m. EDT, allowing the forecast team to give a “go” for weather on the launch.
While cumulus or cumulonimbus clouds near the launch site would indicate the presence of turbulence and possibly strong upper-level wind shear, both of which could affect a rocket’s flight, the only reason for these rules is the potential for lightning.
45th Weather Wing forecasters consider a list of 10 Lightning Launch Commit Criteria (LLCC) leading up to a rocket launch from Kennedy Space Center.
The conditions they were on the lookout for: cumulus clouds or lightning-producing storm clouds over or down-range of the launch site; thick stratus clouds directly above the rocket; anvil clouds (cumulonimbus) or rainy weather to the west of the launch pad; the presence of strong electric fields in the vicinity of the launch site. Any of these conditions could either produce natural lightning, or cause rocket-triggered lightning, which is potentially disastrous for the mission and crew.
The first launch attempt for this mission, on Wednesday, May 27, was called off with just 17 minutes to go before T-zero. The launch team scrubbed the mission due to several weather issues, including rain, cumulus clouds and what NASA called “field mills”. Field mills refers to an instrument used to detect electric field levels in the atmosphere. The presence of strong electric fields in the area is a good indication that there is the potential for lightning in the clouds around the launch site. A rocket launching in such an environment would act as a lightning rod, triggering a lightning stroke even if one was not likely to happen naturally.
The weather factors not included in the forecasters’ Probability of Violation (POV) are the presence of upper level wind shear, solar activity, and the weather and water conditions at the potential recovery locations out on the Atlantic Ocean. These conditions could potentially impact a launch, but they are considered separately from the forecast POV.
On Wednesday, when the 45th Weather Squadron forecasters gave their final “no-go” for the launch, they had said it came down to a 10-minute window. If they could have delayed the launch from 4:33 p.m. EDT to 4:43 p.m. EDT, they likely would have been able to give the go-ahead for lift-off. Since the launch window was instantaneous, however, they were forced to stand down.
This emphasizes that, sometimes, making the “go/no-go” decision for a mission to launch on time can depend on the at-the-moment weather conditions. Even if stormy weather is crossing the launch site before lift-off, they could catch a break in the active weather, or they could get unlucky, and the weather is still too sketchy to risk it.
Past spacecraft that have carried astronauts into orbit were marvels of technology. SpaceX’s Crew Dragon, on the other hand, looks to be something straight out of science fiction that has been made real.
Although the two astronauts appear cramped in the above photograph, the Crew Dragon is surprisingly roomy when compared to older spacecraft. Even the current Soyuz capsules are very crowded, with little room for the astronauts and cosmonauts to move around during a launch.