The FAA’s draft environmental assessment (EA) of SpaceX’s proposal to recover Dragon capsules in the Gulf of Mexico contains several interesting sections detailing the company’s efforts to recover payload fairings and drogue parachute assemblies for the fairings and spacecraft.
The sections are excerpted below. You can read the full report here.
As part of SpaceX’s fairing recovery effort, SpaceX added a parachute system to one of the fairing halves. The parachute system consists of one drogue parachute and one main parafoil. Also, a nitrogen cold gas attitude control system was added to the fairing halves in order to null the initial rotation rates of the fairing halves and re-orient them into a favorable orientation prior to re-entry. SpaceX’s long-term goal is to control the parafoil to return both fairing halves to either a pre-positioned droneship or land. This operation is currently occurring in the Atlantic Ocean following launches from KSC. This program will be extended to include missions from CCAFS and VAFB.
The parachute system slows the descent of the fairing to enable a soft splashdown such that the fairing remains intact. Following re-entry of the fairing into Earth’s atmosphere, a drogue parachute is deployed at a high-altitude (approximately 50,000 feet [ft]) to being the initial slow down and to extract the parafoil. The drogue parachute (and the attached deployment bag) is then cut away follow the successful deployment of the parafoil. The predicted impact points of both the fairing, parafoil, and drogue parachute assembly have been propagated using modeling tools (FAA 2017).
SpaceX is also evaluating two parachute systems for the fairing (Type 1 and Type 2). The specifications of each system are noted below (Tables 1 and 2). The Type 2 system has a similar drogue parachute as the Type 1 but a larger and lighter parafoil than Type 1.
The fairing and parafoil are recovered by a salvage ship that is station in the Range Safety-designated safety zone near the anticipated splashdown area. The salvage ship is able to locate the fairing using GPS data from mission control and strobe lights on the fairing data recorders. Upon locating the fairing, a rigid-hulled inflatable boat (RHIB) is launched. Crew hook rig lines and secure it placing it into a storage drum. However, if sea and weather conditions are poor, recovery of the fairing and parafoil may be unsuccessful.
Drogue Parachute Assembly Recovery
Recovery of the drogue parachute assembly is attempted if the recovery team can get a visual fix on the splashdown location. However, the drogue parachute assembly is deployed at a high altitude, it is difficult to locate. In addition, based on the size of the assembly and the density of the material, the drogue parachute assembly becomes saturated within approximately one minute of splashing down and begins to sink. This makes recovering the drogue parachute assembly difficult and unlikely. However, SpaceX is working on an engineering solution for recovery of the drogue parachute assembly in future operations. They hope to have a solution developed in early 2018, but the timing is uncertain.
The salvage ship returns to a private dock and the fairing is transported to a SpaceX facility via truck. Once at a SpaceX facility, further post-flight processing ensures the fairing is a source of information for continuous program improvement. If this system proves to be effective, the parachute/parafoil system will be added to the second fairing half in the future in order to enable recovery of the full payload fairing system.
Between 2017-2018, SpaceX anticipates 15 launches involving fairing recovery attempts. Four of the 15 launches might also involve attempting to recover both halves of the fairing, thus would involve two drogue parachutes and two main parafoils. Therefore, there is the potential to have up to 19 drogue parachutes and 19 parafoils land in the ocean (Atlantic and Pacific Oceans). Of the 15 launches involving fairing recovery attempts within the next 12-15 months (e.g., 2017-2018). SpaceX anticipates five would occur at VAFB, where the fairing would splash down in the Pacific Ocean. The other ten launches involving fairing recovery would occur in the Atlantic Ocean.
From 2019-2024, SpaceX anticipates the frequency of launches involving fairing recovery to increase. In 2018, SpaceX anticipates approximately two recovery attempts, and from 2019-2024, SpaceX anticipates approximately three recovery attempts per month. Thus, for all seven years, SpaceX anticipates up to 480 drogue parachutes and 480 parafoils would land in the ocean. All years will involve recovery attempts of both halves of the fairing. SpaceX also intends to recover all parachutes and parafoils, but it is possible some of the drogue parachutes and foils will not be recovered due to sea or weather conditions at the time of recovery.
Dragon Drogue Parachute Assembly Recovery
This EA assumes all drogue parachute assemblies are not recovered. However, SpaceX is working on an engineering solution for recovery of the drogue parachute assembly in future operations. They hope to have a solution developed in early 2018, but the timing is uncertain. SpaceX would implement operational controls and contingency planning in an attempt to recover all of the parachutes. These measures would likely include:
- Mobilizing additional recovery resources – most likely one team per parachute;
- Land, ocean, and airborne visual monitoring of the operation; and
- The use of a buoy marking system – attaching appropriately sized buoys immediately upon contact with the parachute would aid in the tracking and retrieval of the parachute.