Cullen Desforges
May 26th, 2020
Crew Dragon and Falcon 9 were lowered to the horizontal today, L-1, as SpaceX engineers worked to prepare for the May 27 launch of Demo-2. It was raised back to vertical later in the afternoon. Credit: Michael McCabe, SpaceFlight Insider
As the world waits with bated breath, the Falcon 9 carrying Crew Dragon stands tall once again on pad 39A, ready to be given the final go for launch. With less than 24 hours remaining in the count, SpaceX is targeting 4:33 p.m. EDT for the departure of Demo-2 mission from historic Launch Complex 39-A at the Kennedy Space Center in Florida.
SpaceX completed a Flight Readiness Review on Friday which included teams from SpaceX, NASA, and International Space Station Operations giving a final safety review of the spacecraft and launch vehicle. Shortly thereafter, SpaceX successfully completed a static fire test of Falcon 9 Friday evening. On May 25, the final Launch Readiness Review was conducted by teams at NASA and SpaceX in order to ensure that Falcon and Dragon are ready to safely fly the crew to orbit. Now that the final go-ahead has been given, NASA and SpaceX are ready to proceed with their first launch attempt on Wednesday.
While the teams and spacecraft may be ready to fly, the million dollar question lies with the weather. Given the nature of Crew Dragon’s abort system, weather has to be “green” for thousands of miles northeast of the Kennedy Space Center, practically to the West Coast of Ireland. There are well over 20 specific weather minimums that need to be met in order to achieve a go status. With a low pressure system moving north from the Florida peninsula, atmospheric instability and cumulonimbus clouds will follow it, possibly making a Wednesday launch attempt challenging. On Monday, the 45th Weather Squadron released the grim outlook of a 60% chance of violating weather constraints for Wednesday; by Monday evening, the forecast had improved to the inverse, that it was now predicted as 60% favorable. If Demo-2 can not fly on Wednesday, the next available window for launch is on Saturday; conditions for that day and the next are looking much more favorable.
The Demo-2 launch schedule data released by NASA, details the various timings for actions and activities surrounding the May 27, 2020 Crew Dragon launch. Data credit: NASA
The launch day will begin with a 9 a.m. wake up call for the crew. They’ll attend a weather briefing at around 12:15 p.m. EST. The crew will arrive at pad 39A at T-minus 2 hours 55minutes. They’ll board Crew Dragon twenty minutes later, where they will be strapped in and perform final communication and leak checks on their spacesuits. The hatch will close at T-minus 1 hour and 55 minutes. If weather appears positive, the launch director will give the go for propellant load at 45 minutes before launch. The crew access arm will retract moments later. After the liquid oxygen and rocket propellant has been loaded, and the final polling is complete, the vehicle will enter startup mode at t-minus 60 seconds to launch. The nine Merlin engines will ignite at t-minus 3 seconds. From there, Falcon 9 and Crew Dragon will take to the skies.
From the naked eye, the liftoff will look fairly similar to the 20 missions which Dragon’s first iteration flew to the international outpost. Much like Space Shuttle launches to the International Space Station, the launch trajectory will carry the launch vehicle on a flight path northeast of the Kennedy Space Center. The vehicle will experience Max-Q, the period of maximum aerodynamic stress on the rocket, at approximately 58 seconds after liftoff.
Planned flight stages of Demo-2, scheduled to launch May 27, 2020. Credit NASA TV
The Falcon 9 first stage will propel Dragon for about two and a half minutes before its nine engines will shut off, and the second stage carrying Crew Dragon will separate from the first stage and begin its push of the spacecraft into low earth orbit. From there, the first stage will begin its boost back burn to align itself on a trajectory to return to earth. True to form of most recent SpaceX missions to the International Space Station, the company will attempt to land the first stage on the autonomous drone ship “Of Course I Still Love You” approximately 9 minutes and 22 seconds after liftoff.
Once Crew Dragon separates from the second stage at approximately 8 minutes and 52 seconds after liftoff, the spacecraft’s onboard computers and crew will get to work, performing several key functions to test Dragon’s capability of on orbit maneuvering. As spacecraft Commander, Astronaut Doug Hurley will act as the crew member monitoring these functions. While NASA did not give a specific time the spacecraft will reach the ISS, it could take up to two days for Dragon to reach its intended target, depending on the amount of tests NASA and SpaceX want to perform on the vehicle before initiating docking procedures. The first half of Dragon’s journey on orbit can be broken down into five key tasks that must be completed on the way to the ISS: orbit activation, phasing burns, approach initiation, proximity operations, and docking and pressurization initiated at the rendezvous point with the ISS. These key functions can and will be performed autonomously by the Crew Dragon vehicle, but can be initiated and controlled by the crew at any phase of the flight should an anomaly occur within any of the vehicle’s onboard systems. Once Dragon arrives at the Station, it will pressurize itself to match the pressure of the orbiting laboratory. From there, the crew will be able to open the hatch and initiate arrival procedures.
The exact duration for Crew Dragon’s ISS stay is still yet to be determined, however, as discussed in a May 1 press conference by NASA’s deputy Manager of commercial crew Steve Stitch, it is expected that Crew Dragon will stay docked to Station anywhere from 30-119 days. Any time beyond the 119 days could possibly result in a degradation of Dragon’s solar panels.
Astronauts Bob Behnken and Doug Hurley stand in front of LC-39A and their Falcon 9 rocket at Kennedy Space Center. Photo credit: NASA
After the crew completes the required on-Station tasks, Crew Dragon will get to work initiating departure and reentry procedures. As pictured above, the reentry process for Crew Dragon consists of five tasks that must be completed prior to parachute deployment and splashdown in the Atlantic Ocean. Dragon will slowly depart the Station and close the “hood” of its hatch. Once the spacecraft is beyond the space station’s 200 meter “keep-out sphere,” Dragon will perform a series of phasing burns to orient itself on the proper alignment to set up for reentry. It will then jettison its trunk and start its autonomous deorbit burn. After completing reentry, Dragon’s four Mark III parachutes will deploy, guiding the vehicle to a gentle splashdown in the Atlantic Ocean off the coast of Florida.
If Crew Dragon and Demo-2 perform nominally, it will allow the spacecraft to be fully certified to ferry humans to and from the International Space Station, opening the door for the first operational Crew Dragon mission, Crew-1, to take place later this year.
Cullen Desforges
Having a life-long interest in crewed space flight, Desforges’ passion materialized on a family vacation in 1999 when he was able see the launch of Space Shuttle Discovery on STS-96. Since then, Desforges has been an enthusiast of space exploration efforts. He lived in Orlando, Florida for a year, during which time he had the opportunity to witness the flights of the historic CRS-4 and EFT-1 missions in person at Cape Canaveral. He earned his Private Pilot Certificate in 2017, holds a degree in Aviation Management, and currently works as an Operations Analyst in the aviation industry in Georgia.
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