At three seconds before the scheduled liftoff, the nine Merlin 1D engines on the Block 5 Falcon 9 rocket ignited. The rocket’s fuel mixture of liquid oxygen and a highly-refined kerosene, called RP-1, created the unique green flash below the engine nozzles at the moment of ignition. A brighter white flash accompanied the roar of the engines, and the billowing clouds of steam from the water deluge system followed in the next few seconds, as the engines lifted the rocket off the pad with 1.7 million pounds (7,600 kilonewtons) of thrust. The rocket cleared the tower and thundered into the sky, gaining altitude and speed as it began to arc into its northeasterly trajectory, setting itself on the path to catch up to the ISS.

 

About 58 seconds into the flight the vehicle passed through Max Q, the phase of the flight where the combination of velocity and atmospheric pressures on the vehicle are at their highest. The rocket climbed through this phase, going higher and faster for about another 85 seconds, until the nine Merlin 1D engines on the first stage booster shut down about 2 minutes and 23 seconds after the rocket had left the pad. Four seconds later the first stage separated.

The CRS-16 Dragon spacecraft perched atop the Block 5 Falcon 9 rocket at Canaveral’s SLC-40. Photo Credit: Mike Howard / SpaceFlight Insider

Over the next several seconds a number of events occurred in rapid succession. Moments after first stage separation, the booster reignited with the first of a series of thrust bursts which, along with movements of its four latticed grid fins, would guide the booster back toward Cape Canaveral for a landing at the SpaceX Landing Zone 1 (LZ1).

Seconds after the beginning of the boostback burn on the first stage, the lone Merlin 1D-Vacuum (MVAC) second stage engine ignited, pushing the Dragon spacecraft on toward orbit with its 210,00 pounds (934 kilonewtons) of thrust. About 30 seconds later the payload fairing was jettisoned, exposing the Dragon spacecraft to space.

During its first orbit, the Dragon deployed its twin solar panels to provide power to the spacecraft. Over the next two days, the spacecraft is scheduled to use its system of Draco thruster engines to carry out a set of burns and maneuvers to raise its orbit and bring it to a loitering position in the vicinity of the ISS.

Maneuvers and investigations

Another set of maneuvers will edge the Dragon closer to the ISS, where Expedition 57 Commander Alexander Gerst will use the Canadarm2 to grapple the spacecraft and rotate it into position to dock it to the station’s Harmony module. 

The CRS-16 Dragon is scheduled to be berthed to the station in about two days. Photo Credit: NASA

In addition to food, water, tools, computers, spacewalk hardware, and other equipment, the ISS crew will unpack from CRS-16 a number of research investigations and experimental hardware.

One of these investigations critical to the future of long duration spaceflight is the Robotic Refueling Mission 3 (RRM3). It is a set of tools that will demonstrate the transfer and long-term storage of cryogenic fuels in space. Demonstrating this capability will be an essential step to enabling long duration journeys to the Moon or Mars.   

CRS-16 is also carrying the Global Ecosystems Dynamics Investigation, or GEDI, which is pronounced like “Jedi” from Star Wars fame. It is a sophisticated lidar instrument that will use reflected and measured laser pulses to form a global map of the Earth’s temperate and tropical forests. These high-resolution observations will provide scientists with data on what areas of forest are storing the most carbon, and how disturbance of those forests might affect carbon quantities in the Earth’s atmosphere.

The primary purpose of today’s flight was to send experiments and supplies to the ISS. The secondary mission, returning the first stage to Earth was not a success. After leaving the launch pad nearly 8 and a half minutes earlier, the first stage Falcon 9 booster heralded its return arrival with an impressive series of sonic booms. However after that things went, as they say in the space business “off nominal” and saw the first stage end up in the Atlantic.

According to Musk, the hydraulic function didn’t operate correctly and the Falcon 9 began to spin upon its descent. When it touched down it tipped over and splashed into the ocean.

SpaceX’s CEO and Chief Rocket Designer tweeted that the: Grid fin hydraulic pump stalled, so Falcon landed just out to sea. Appears to be undamaged & is transmitting data. Recovery ship dispatched. Some reports have it that the stage may be salvaged, possibly for reuse.

After about five weeks on the ISS, CRS-16 is scheduled to be repacked with materials and experiments for return to Earth, and be unberthed from the station on Jan. 13, 2019.

After maneuvering to a higher orbit to release a number of Cubesats, the spacecraft is expected to perform its re-entry burn, deploy parachutes, and splashdown in the Pacific Ocean off the coast of Baja, California. There it is scheduled to be recovered, and its cargo of experimental investigations and equipment returned to their various scientific institutions for further study.    

Due to an issue with one of the stage’s grid fins, the Falcon 9’s first stage was not able to land at Canaveral’s LZ-1. Photo Credit: Mike Deep / SpaceFlight Insider