Autonomous spaceport drone ship

Just Read the Instructions

Aerial view of the ASDS
Career
Class and type:	Deck barge
Name:	Marmac 300[1][2][3]
Owner:	Marmac, LLC.[1]
Operator:	McDonough Marine Service[4]
Port of registry:	New Orleans, Louisiana[4]
Builder:	Gulf Coast Fabrication Pearlington, Mississippi[1][5]
Completed:	1998
Acquired:	1 May 1998[5]
Identification:	USCG ID 1063184[1] Hull No. 291[5]
Fate:	Converted for SpaceX
Career
Name:	Just Read the Instructions[6]
Operator:	SpaceX
In service:	November 2014
Status:	Active, in service
General characteristics as deck barge (1998–2014)
Tonnage:	4,422 GT,[1] 1,326 NT,[1] 10,105 LT DWT[7]
Length:	288 ft (87.8 m)[1]
Beam:	100 ft (30.5 m)[1]
Depth:	19.8 ft (6.0 m)[1]
Crew:	0
General characteristics as drone ship (2014–present)
Length:	300 ft (91.4 m)[8]
Beam:	170 ft (51.8 m)[8]
Depth:	19.8 ft (6.0 m)[1]
Installed power:	Generator units
Propulsion:	4 × 300 hp (220 kW) azithrusters with 1 m (40 in) nozzles, as of January 2015[9]
Aviation facilities:	Landing platform for returning rocket stages
Notes:	Autonomous or remote-controlled operation modes are available during rocket landing operations[2]

Just Read the Instructions—also known as the autonomous spaceport drone ship (ASDS)—is an ocean-going, barge-derived, floating landing platform that aerospace company SpaceX is attempting to use to receive returning first stages after they have lofted spacecraft into orbit.

The ship was converted from a barge named Marmac 300 in late 2014 and was deployed in January 2015 during the CRS-5 cargo resupply mission to the International Space Station in order to provide a landing platform for a test flight of the returning booster stage.

It forms an important element of the SpaceX reusable launch system development program which aims to significantly lower the price of space launch services.^[2]

SpaceX plans to eventually use the ASDS as a floating launch platform, refuelling a landed first stage with sufficient fuel to enable it to fly back to its launch site. No date has been provided for when this capability would be developed, tested or made operational.^[10]

History

As early as 2009 SpaceX CEO Elon Musk articulated ambitions for "creating a paradigm shift in the traditional approach for reusing rocket hardware."^[10]

In October 2014 SpaceX publically announced that they had contracted with a Louisiana shipyard to build a floating landing platform for reusable orbital launch vehicles. Early information indicated that the platform would carry an approximately 90-by-50-meter (300 ft × 160 ft) landing pad and would be capable of precision positioning so the platform can hold its position for launch vehicle landing.^[11][12]

On 22 November 2014 Musk released a photograph of the "Autonomous spaceport drone ship" along with additional details of its construction and size.^[10][13]

As of mid-December 2014, the ship was based in Jacksonville, Florida, at the northern tip of the Jacksonville Port Authority's JAXPORT Cruise Terminal (30°24′33″N 81°34′57″W / 30.409144°N 81.582493°W / 30.409144; -81.582493) where SpaceX have built a stand to secure the Falcon stage during post-landing operations. The stand consists of four 15,000 lb (6,800 kg), 107 in (270 cm) tall and 96.25 in (244.5 cm) wide pedestal structures bolted to a concrete base. A mobile crane will lift the stage from the ship and place it on the stand. Tasks such as removing or folding back the landing legs prior to placing the stage in a horizontal position for trucking will occur here.^[14]

The ASDS landing location for the first landing test was in the Atlantic Ocean approximately 200 miles (320 km) northeast of the launch location at Cape Canaveral, and 165 miles (266 km) southeast of Charleston, South Carolina.^[2][3]

On 23 January 2015, during repairs to the ship following the unsuccessful first test, SpaceX CEO Elon Musk announced that the ship was to be named Just Read the Instructions,^[15] with a sister ship planned for West Coast launches to be named Of Course I Still Love You.^[16] On 29 January, SpaceX released a manipulated photo of the ship with the name illustrating how it would look like once painted on the deck, confirming the new designation.^[6] Both ships are named after two GCUs (General Contact Units, spaceships commanded by autonomous artificial intelligences) that appear in The Player of Games, a Culture novel by Iain M. Banks.

Deck barge

In 2003, the Marmac 300 was used to raise the forward half of the sunken Delta Conveyor. The 4,000-short-ton (3,600 t) lift was reportedly the largest lift ever accomplished on the Mississippi River. The task was accomplished by sinking the bow of the Marmac 300 into a 140-by-70-by-20-foot (42.7 × 21.3 × 6.1 m) trench that was dredged into the bottom of the river before pulling the wreck onto the inclined barge using chain pullers.^[17]

In 2011, the barge was used to successfully launch the oceanographic research vessel Cabo de Hornos after the ship was beached by the tsunami which followed the 8.8-magnitude Chilean Earthquake of 2010.^[18][19]

Characteristics

This autonomous vessel is capable of precision positioning to within 3 meters (9.8 ft) even under storm conditions^[13] using GPS position information^[20] and four diesel-powered azimuth thrusters.^[21] In addition to the autonomous operating mode, the ship may also be telerobotically controlled.^[2]

The azimuth thrusters are hydraulic propulsion outdrive units with modular diesel-hydraulic-drive power units and a modular controller all manufactured by Thrustmaster, a marine equipment manufacturer.^[10]

The landing platform on the upper deck is 52 m × 91 m (170 ft × 300 ft) while the span of the Falcon 9 landing legs is 18 m (60 ft). The returning rocket must not only land within the confines of the deck surface but must also deal with ocean swells and GPS errors.^[10][22]

Operation

During rocket landing operations, a separate support ship will be standing by some distance away from the uncrewed drone ship. Following landing, technicians and engineers will reboard the landing platform, and secure the rocket's landing legs to lock the vehicle in place for transport back to port.^[2]

Test landing

The autonomous ship was used for a flight test the first time on 10 January 2015^[23] when SpaceX conducted a controlled descent flight test to land the first stage of Falcon 9 Flight 14 on a solid surface after it was used to loft a contracted payload toward Earth orbit.^[11][12]

SpaceX projected prior to the flight that the likelihood of successfully landing on the platform on the first try would be 50 percent or less.^[10][12]

10 January 2015 landing attempt

SpaceX did attempt a landing on the drone ship on 10 January 2015. Many of the test objectives were achieved, including precision control of the rocket's descent to land on the platform at a specific point in the south Atlantic ocean and a large amount of test data was obtained from the first use of grid fin control surfaces used for more precise reentry positioning. However the landing was a hard landing and SpaceX is currently working to recover parts of the vehicle for testing and analysis.^[24]

The SpaceX webcast indicated that the boostback burn and reentry burns for the descending first stage occurred, and that the descending rocket then went "below the horizon," as expected, which eliminated the live telemetry signal. Shortly thereafter, SpaceX released information that the rocket did get to the drone spaceport ship as planned, but "landed hard ... Ship itself is fine. Some of the support equipment on the deck will need to be replaced."^[25][24] According to the Vine hosted video, the rocket approached slightly too fast with an angle of 45°, thus crashing.^[26]

11 February 2015 landing attempt

The DSCOVR satellite was launched on 11 February 2015. Because of the additional performance required to inject the satellite into an L₁ injection orbit, the first stage reached an apogee of 135 km (84 mi) and re-entered the atmosphere with four times the heating load as compared to the 10 January landing attempt.^[27]

Because of ocean conditions, the landing, which was postponed to 11 February, did not come to pass. 7 m (23 ft) high waves interfered with the ASDS recovery duties and so instead of landing it on the barge SpaceX tried a soft landing in the sea to gather information to use for next landing attempts. The soft landing was successful, as SpaceX CEO Elon Musk tweeted that it landed 10 m (33 ft) away from target and in a vertical position while overcoming heavy storms, which lead him to believe that, if the landing had been tried on the barge, it would have been a success.^[28]

14 April 2015 landing attempt

On 14 April 2015, SpaceX made another attempt to land a Falcon first stage on the drone ship. Early news from Elon Musk suggested that it made a hard landing on the drone ship.^[29] He later clarified that it appeared to have made a vertical landing on the ship, but then toppled over due to excessive remaining lateral momentum.^[30]

See also

• Port of Jacksonville
• Very-small-aperture terminal

References

External links

Wikimedia Commons has media related to Autonomous spaceport drone ship.

• Thrustmaster drive unit specifications

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