Ms. Tree (ship)


Ms. Tree, formerly known as Mr. Steven, and its sister ship, Ms. Chief are marine vessels chartered by SpaceX as platforms for recovery of rocket payload fairings. These ships have been retrofitted with large nets that are intended to catch fairings—to prevent the fairings from making contact with seawater—as a part of an iterative development program to create technology that will eventually allow rocket payload fairings to be economically reused and reflown.
Ms. Tree was used for SpaceX Falcon 9 fairing recovery experiments on a number of occasions in 2018 and early 2019, while named Mr. Steven. The ship first successfully caught a descending fairing in its large net on June 25, 2019 during the STP-2 mission from a Falcon Heavy flight, coincidentally on its first fairing recovery voyage after the ship had been renamed Ms. Tree following a change of ownership.

History

The ship was originally built in 2014 for SeaTran as a platform supply vessel to support fast crew transport operations. The vessel was named Mr. Steven after Steven Miguez, the father of SeaTran CEO Blake J. Miguez.
The vessel subsequently was chartered by SpaceX for an experimental program to provide surface marine "catch and recovery" operations for a test program attempting to bring the large Falcon 9 launch vehicle satellite fairingsseparated at high speed and high altitudethrough atmospheric reentry and parachute descent to the ocean surface in a controlled way, and then recover them for evaluation and potential reuse. Since satellite fairings are traditionally expended into the ocean, the fairings used for these tests were somewhat modified test articles. As part of that effort, Mr. Steven was fitted in July 2018 with four large arms which support an elevated horizontal net, similar to a giant trampoline or trapeze net.
In July 2018, Mr. Steven was upgraded and refitted with a much larger net with an area of, four times the original net size. The upgrade included replacing the original rigid arms and fitting four new arms, which are each supported and positioned by two extendable shock-absorbing booms. Each arm can be removed and disassembled into six subsections.
In June 2019, Mr. Steven was renamed Ms. Tree, after being purchased by Guice Offshore, a company with a long-standing contractual relationship to SpaceX as a provider of a variety of marine services.
On June 25, 2019, SpaceX successfully caught its first-ever fairing half on Ms. Tree in the Atlantic Ocean off the Florida coast as part of the Falcon Heavy STP-2 mission.
On August 6, 2019, Ms. Tree was used to successfully catch another fairing half from a Falcon 9 that successfully launched Amos-17. SpaceX has two complete fairing halves that have reentered from space and been recovered dry, without contacting the saltwater. It is important to maintain a clean environment inside the fairing to protect future payloads.
In August 2019, SpaceX chartered the sister ship to Ms. Tree, the Ms. Chief, as the second fairing catcher vessel so that it could be possible to retrieve both halves of the same fairing on a Falcon 9 launch. This second ship is also operated by Guice Offshore, and is therefore titled "GO Ms. Chief" on the ship sides. Ms. Chief was outfitted with a matching set of four wide arms and a catch net by October 2019, in preparation for dual simultaneous fairing recovery attempts.
On 11 November 2019, during the Starlink L1 mission both ships were sent to sea but were recalled due to rough seas so a recovery was not attempted.
On 16 December 2019, both ships were positioned in the Atlantic ocean for a recovery attempt, but both ships narrowly missed catching the fairing halves.
On 29 January 2020, both ships were positioned for a recovery attempt for the Starlink 3 launch. Ms. Tree caught one fairing half, but Ms. Chief narrowly missed the other fairing half.
On 20 July 2020, both fairing halves were successfully caught for the first time by both ships during the Anasis-2 mission.

Fairing reuse

During the first six decades of spaceflight, payload fairings were expended by atmospheric reentry and allowed to drop into the ocean as debris/flotsam.
In 2018, SpaceX began flight test experiments with fairings descending from sub-orbital trajectories above the atmosphere on its Falcon 9 rockets.
As a part of the SES-10 mission in March 2017, SpaceX successfully performed a controlled landing of the payload fairing into the ocean for the first time. SpaceX was able to recover the fairing half from the water after it landed, aided by attitude-control thrusters and a steerable parachute, gently on water. At the SES-10 news conference, the company announced its intent to land the fairings on a dry flexible structure, jokingly described by Elon Musk as a "floating bouncy castle", with the goal of reusing the fairings. The cost of a fairing is about $6 million which accounts for 10 percent of overall launch costs.
The "bouncy castle" idea led to SpaceX contracting for the fast vessel Mr. Steven which has had modifications to facilitate a large net being strung between long arms that extend considerably beyond the width of the ship. Mr. Steven is equipped with a dynamic positioning system and was first tested after the launch of the Paz satellite from Vandenberg Air Force Base in February 2018. The test was not fully successful because the fairing missed the boat by a few hundred meters but landed safely in the water before being recovered and taken back to port. All four attempts in the first half of 2018 to land a fairing on the recovery ship failed, despite fitting Mr. Steven with larger nets before the July 2018 attempt.
In October 2018, to practice recovery outside mission situations, SpaceX performed drop tests of a fairing half from a helicopter with Mr. Steven below. The outcome of the tests has not been publicly released.
On the ArabSat-6A mission on April 11, 2019, SpaceX used the recovery boats GO Searcher and GO Navigator to recover both fairing halves quickly after they landed in the sea; Musk declared the recovery successful and reused the fairings in a later Starlink mission. SpaceX used the same recovery method in May 2019 on another Starlink launch.
A first successful fairing catch was made as part of the STP-2 mission on June 25, 2019.

External references

  • , with catch by Ms. Tree. SpaceX video, 6 August 2019.