An autonomous spaceport drone ship (ASDS) is an ocean-going vessel derived from a deck barge, outfitted with station-keeping engines and a large landing platform. Construction of such ships was commissioned by aerospace company SpaceX to allow for recovery of rocket first-stages at sea for high-velocity missions which do not carry enough fuel to return to the launch site after lofting spacecraft onto an orbital trajectory.
SpaceX has two operational drone ships and has a third under construction as of early 2018. Just Read the Instructions operates in the Pacific for launches from Vandenberg; Of Course I Still Love You operates in the Atlantic for launches from Cape Canaveral. A Shortfall of Gravitas is under construction. As of 7 August 2018, 23 Falcon 9 flights have attempted to land on a drone ship, with 17 of them succeeding.
The ASDS ships are a key component of the SpaceX reusable launch system development program which aims to significantly lower the price of space launch services through “full and rapid reusability.” Any flights going to geostationary orbit or exceeding escape velocity will require landing at sea, encompassing about half of SpaceX missions.
Purpose
SpaceX wants to develop and test the reusability of its Falcon 9 rocket. According to company founder Elon Musk, fully reusable rockets could reduce the cost of launching Earth orbit by a factor of 100. The aim is that first the first rocket stage landed near the launch site in order to then be able to refuel.
The first stage of the Falcon 9 rocket, in addition to the structure and tanks for rocket kerosene and liquid oxygen, sensors and control electronics for the launch of nine rocket engines of SpaceX in-house development Merlin. The second stage of the current 2014 Falcon 9, however, is powered only by a Merlin rocket engine. With a successful development of first-tier return capability, SpaceX could already secure approximately 90 percent of Falcon 9’s fabric for further flights.
In order to achieve this goal, first start and landing tests were carried out with the test rocket Grasshopper, a converted first stage of the Falcon 9 with four fixed landing feet and only one rocket engine. This was followed by similar tests with the Falcon 9 Reusable Development Vehicle 1, which built on the first stage of the larger Falcon 9 v1.1. The rocket had like the Falcon 9 nine Merlin engines and was also equipped with an extendable landing gear and later four lattice fins for control.
Now landing tests are carried out with regular first rocket stages. These take place in the course of a rocket launcher that SpaceX carries out for NASA or commercial customers. The first stage of the Falcon 9 rocket is braked after disconnection with its own engine and falls, controlled by means of lattice fins, controlled back to Earth. At the landing site, re-firing of the steerable engines will allow a controlled landing similar to the landing of the lunar module during the Apollo program on the Moon.
Ship concept, design and operation
The long-term goal of SpaceX is to bring both stages of a rocket back to the launch site. With the use of a landing platform floating on the ocean, in the test phase of the technique the danger of humans was avoided, which would be to be feared if a controlled return over inhabited land fails. The founder and CEO of SpaceX, Elon Musk, estimated in advance the probability of success of the first landing attempt with 50 percent, in the first year of testing with 80 percent.
Since a landing missile stage with the jet engine pointing downwards would pose a significant risk to the crew of the platform during deceleration, and the platform could also be expected to crash from crashes to crashes, the platform was executed unmanned.
The first Autonomous spaceport drone ship received a Landedeck during the conversion of the Marmac 300, which is about 90 meters long and 50 meters wide. In addition, it has a capacity of 15,000 cubic meters of ballast water since then, which stabilizes the position of the platform.
The Falcon 9 requires a landing area of about 22 meters wide, so that when placed on the floating platform a very precise control of both the rocket and the ship is required. Therefore, the autonomous spaceport drone ship with four driven by diesel engines is azimuth thruster (Portable Dynamic Positioning System) of the US company Thrustmaster. With the help of GPS radiolocation it can thus maintain its position automatically against wind and water currents. Even in a storm, the landing platform should not deviate more than 3 meters from its intended position. In addition, the ship has no own propulsion and is towed to its location.
After a storm that caused major damage, the platform was rebuilt in March and April 2015. Among other things, two thrust units were replaced by stronger ones (now each about 1000 hp) and installed a breakwater wall.
History
In 2009, SpaceX CEO Elon Musk articulated ambitions for “creating a paradigm shift in the traditional approach for reusing rocket hardware.”
In October 2014, SpaceX publicly 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 that the platform could hold its position for launch vehicle landing. On 22 November 2014 Musk released a photograph of the “autonomous spaceport drone ship” along with additional details of its construction and size.
As of December 2014, the first drone ship used, the McDonough Marine Service’s Marmac 300 barge, was based in Jacksonville, Florida, at the northern tip of the JAXPORT Cruise Terminal (30.409144°N 81.582493°W) where SpaceX 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.
The ASDS landing location for the first landing test was in the Atlantic approximately 200 miles (320 km) northeast of the launch location at Cape Canaveral, and 165 miles (266 km) southeast of Charleston, South Carolina.
On 23 January 2015, during repairs to the ship following the unsuccessful first test, Musk announced that the ship was to be named Just Read the Instructions, with a sister ship planned for west coast launches to be named Of Course I Still Love You. On 29 January, SpaceX released a manipulated photo of the ship with the name illustrating how it would look once painted. Both ships are named after two General Contact Units, spaceships commanded by autonomous artificial intelligences, that appear in The Player of Games, a Culture novel by Iain M. Banks.
The first Just Read the Instructions was retired in May 2015 after approximately six months of service in the Atlantic, and its duties were assumed by Of Course I Still Love You. The former ASDS was modified by removing the wing extensions that had extended the barge surface and the equipment (thrusters, cameras and communications gear) that had been added to refit it as an ASDS; these items were saved for future reuse. In 2018, SpaceX began construction of a third barge, A Shortfall of Gravitas.
The active ASDS fleet
In early 2015, SpaceX leased two additional deck barges—Marmac 303 and Marmac 304—and initiated refit to construct two additional autonomous-operation-capable ASDS ships, built on the hulls of these Marmac barges.
Of Course I Still Love You
The second ASDS barge, Of Course I Still Love You (OCISLY), had been under construction in a Louisiana shipyard since early 2015 using a different hull—Marmac 304—in order to service launches on the east coast. It was built as a replacement for the first Just Read the Instructions and entered operational service for Falcon 9 Flight 19 in late June 2015. As of June 2015, its home port was Jacksonville, Florida, but after December 2015, it was transferred 160 miles (260 km) further south, at Port Canaveral.
While the dimensions of the ship are nearly identical to the first ASDS, several enhancements were made including a steel blast wall erected between the aft containers and the landing deck. The ship was in place for a first-stage landing test on the CRS-7 mission, which failed on launch on 28 June 2015.
On 8 April 2016 the first stage, which launched the Dragon CRS-8 spacecraft, successfully landed for the first time ever on OCISLY, which is also the first ever drone ship landing.
In February 2018, the Falcon Heavy Test Flight’s central core exploded upon impact next to OCISLY that damaged two of the four thrusters on the drone ship. Two thrusters were removed from the Marmac 303 barge in order to repair OCISLY.
Just Read the Instructions
The third ASDS barge, using the Marmac 303 hull, was built during 2015 in a Louisiana shipyard, and the barge transited the Panama Canal in June 2015 carrying its wing extensions as cargo on the deck because the ASDS, when complete, would be too wide to pass through the canal.
The home port for the Marmac 303 is the Port of Los Angeles, at the AltaSea marine research and business campus in San Pedro’s outer harbor. The landing platform and tender vessels began docking there in July 2015 in advance of the main construction of AltaSea which is scheduled for 2017.
SpaceX announced that the Marmac 303 would be the second ASDS to be named Just Read the Instructions (JRtI) in January 2016, shortly before its first use as a landing platform for Falcon 9 Flight 21.
On 17 January 2016, JRtI was put to first use in an attempt to recover a Falcon 9 first-stage booster from the Jason-3 mission from Vandenberg. The booster successfully landed on the deck; however, a lockout collet failed to engage on one of the legs causing the rocket to tip over, exploding on impact with the deck. On January 14, 2017, SpaceX launched Falcon 9 Flight 29 from Vandenberg and landed the first stage on the JRtI that was located about 370 km (230 mi) downrange in the Pacific Ocean, making it the first successful landing in the Pacific.
Under construction
SpaceX began construction of a fourth deck barge in early 2018.
A Shortfall of Gravitas
The fourth ASDS barge was announced to be under construction in February 2018 and it will become the second active east coast-based ASDS. It will be homeported at Port Canaveral. This future simultaneously usable ASDS, along with OCISLY, is called A Shortfall of Gravitas (ASoG) and like the rest of the fleet, its naming is based on names used in the Culture series. The droneship is expected to be operational in mid-2019.
Characteristics
The ASDS are autonomous vessels capable of precision positioning, originally stated to be within 3 meters (9.8 ft) even under storm conditions, using GPS position information and four diesel-powered azimuth thrusters. In addition to the autonomous operating mode, the ships may also be telerobotically controlled.
The azimuth thrusters are hydraulic propulsion outdrive units with modular diesel-hydraulic-drive power units manufactured by Thrustmaster, a marine equipment manufacturer in Texas. The returning rocket must not only land within the confines of the deck surface but must also deal with ocean swells and GPS errors.
SpaceX equips the ships with a variety of sensor and measurement technology to gather data on the booster returns and landing attempts, including commercial off the shelf GoPro cameras.
At the center of the ASDS landing pads is a circle that encloses the SpaceX stylized “X” in an X-marks-the-spot landing point.
Naming
The two ASDS names used so far, Just Read the Instructions (JRtI), and Of Course I Still Love You (OCISLY), pay homage to the works of the late science fiction author Iain M. Banks by being based on his Culture fictional universe. Both JRtI and OCISLY are names of enormous, sentient starships, which appeared in the novel The Player of Games. The third name that will be used for the fourth ASDS will be A Shortfall of Gravitas (ASoG) that is similarly drawn from the Culture-milieu of Iain M. Banks. The Culture series has a running gag on having some starships that include “Gravitas” within their names.
Just Read the Instructions (Marmac 300)
The landing platform of the upper deck of the first barge named Just Read the Instructions was 52 m × 91 m (170 ft × 300 ft) while the span of the Falcon 9 v1.1 landing legs was 18 m (60 ft). The vessel was retired in 2015.
Of Course I Still Love You (Marmac 304)
Of Course I Still Love You was built as a refit of the barge Marmac 304 for landings in the Atlantic Ocean. Its homeport is in Port Canaveral, Florida since December 2015, after being ported for a year at the Port of Jacksonville during most of 2015.
Just Read the Instructions (Marmac 303)
Just Read the Instructions, the second barge with that name, was built as a refit of the barge Marmac 303 in 2015 for landings in the Pacific Ocean. Its homeport is the Port of Los Angeles, California.
A Shortfall of Gravitas (under construction)
The fourth ASDS is named A Shortfall of Gravitas, under construction as of early 2018, will be used on the east coast to support high flight rates for Falcon 9 and tandem ocean landings for Falcon Heavy side boosters.
Operation
A tug is used to bring the ASDS to its oceanic position, and a support ship stands by some distance away from the crewless ASDS. The vessels initially used on the east coast were Elsbeth III (tug) and Go Quest (support). Following landing, technicians and engineers typically board the landing platform, and secure the rocket’s landing legs to lock the vehicle in place for transport back to port. The rocket stage is secured to the deck of the drone ship with steel hold downs welded on to the feet of the landing legs. In June 2017, OCISLY started being deployed with a robot that drives under the rocket and grabs onto the hold-down clamps located on the outside of the Falcon 9’s structure after landing. Fans call the robot “Optimus Prime” or “Roomba,” the latter of which has been turned into a backronym for “Remotely Operated Orientation and Mass Balance Adjustment.”
Ship concept, design and operation
The long-term goal of SpaceX is to bring both stages of a rocket back to the launch site. With the use of a landing platform floating on the ocean, in the test phase of the technique the danger of humans was avoided, which would be to be feared if a controlled return over inhabited land fails. The founder and CEO of SpaceX, Elon Musk, estimated in advance the probability of success of the first landing attempt with 50 percent, in the first year of testing with 80 percent.
Since a landing missile stage with the jet engine pointing downwards would pose a significant risk to the crew of the platform during deceleration, and the platform could also be expected to crash from crashes to crashes, the platform was executed unmanned.
The first Autonomous spaceport drone ship received a Landedeck during the conversion of the Marmac 300, which is about 90 meters long and 50 meters wide. In addition, it has a capacity of 15,000 cubic meters of ballast water since then, which stabilizes the position of the platform.
The Falcon 9 requires a landing area of about 22 meters wide, so that when placed on the floating platform a very precise control of both the rocket and the ship is required. Therefore, the autonomous spaceport drone ship with four driven by diesel engines is azimuth thruster (Portable Dynamic Positioning System) of the US company Thrustmaster. With the help of GPS radiolocation it can thus maintain its position automatically against wind and water currents. Even in a storm, the landing platform should not deviate more than 3 meters from its intended position. In addition, the ship has no own propulsion and is towed to its location.
After a storm that caused major damage, the platform was rebuilt in March and April 2015. Among other things, two thrust units were replaced by stronger ones (now each about 1000 hp) and installed a breakwater wall.
First Landing Tests
SpaceX uses rocket stages for the tests, which are already being used for commercial satellite launches or for the supply flights to the International Space Station (ISS) on behalf of NASA. These paid by the client rockets need only be additionally equipped with the landing control and retractable landing legs. Subsequently, it is planned to refuel the landed rocket stage on a trial basis and to start again.
Already in the apron, z. For example, in April and July 2014, SpaceX had launched two commercial satellite missions, such as For example, for Orbcomm, the first stage could be landed on a trial basis in a controlled manner, but then just directly on the ocean, where the steps disappeared.
The first rocket launch was SpaceX’s fifth supply flight to the ISS (SpaceX CRS-5), scheduled for December 16, 2014, but deferred to January 10, 2015 due to engine problems.
First attempt: SpaceX CRS-5
On the fifth supply flight to the ISS, the launch of the Falcon 9 on 10 January 2015 at 9:47 UTC and the transport of the cargo space ship Dragon into orbit. The first stage could again be controlled back into the atmosphere as intended and also reached the landing craft. The rocket stage crashed on landing. According to Elon Musk, there was not enough 10% hydraulic fluid on board, so the four lattice fins mounted on top of the rocket lost their stabilization and control function. The landing platform was only slightly damaged.
The ship was stationed at about 320 miles northeast of the launch site of the Cape Canaveral Air Force Station at 30.8 degrees north latitude and 78.1 degrees west longitude.
2nd attempt: Launch of the Deep Space Climate Observatory
On Feb. 11, 2015 SpaceX launched a Falcon 9 rocket on behalf of the USAF NASA and NOAA project Deep Space Climate Observatory, and wanted to do the second landing attempt. However, a strong storm in the landing area did not allow the drone ship to be used. However, it was possible to control the rocket with a deviation of only 10 meters to the originally intended position.
3rd attempt: SpaceX CRS-6
On the sixth supply flight to the ISS, Falcon 9 was launched on 14 April 2015 at 20:10:41 UTC. As in the first test, the first stage reached the autonomous spaceport drone ship with the new name Just Read the Instructions. However, the first step came obliquely after an approach, in which she staggered strongly to the vertical, and crashed.
4th attempt: SpaceX CRS-7 (failed)
In the seventh supply flight to the ISS after the planning exploded on June 28, 2015, the Falcon 9 used. Thus, the return attempt was omitted in the first time the second ASDS, Of Course I Still Love You should be used.
5th attempt: Jason-3
On January 17, 2016, the last Falcon 9 version 1.1 with the Earth observation satellite Jason 3 launched on board the Vandenberg Air Force Base. The satellite was successfully transported to orbit. The starting parameters would have allowed a return of the first stage to the launch site in principle, but it was not granted in time for approval by the competent environmental authority for land landing. Therefore, a ship landing on the Pacific was planned. On landing, one of the four landing legs gave way, presumably it was not locked in the open position. Due to lack of stability, the rocket stage tipped over on the landing platform and was largely destroyed. Pictures showed that the engine block was left on the deck.
6th attempt: SES-9
For the launch of SES-9 on March 4, 2016 SpaceX was predicted by the launch parameters a very low probability of success. In contrast to the previous attempts with an engine, three engines were used to decelerate. The landing failed and I sank again damaged, u. a. with a hole in the deck and some debris of the rocket on the deck back to the harbor.
7th attempt: CRS-8
On April 8, 2016, a Falcon 9 was launched for a supply mission to the ISS. 9 minutes and 10 seconds after the successful start, the first step continued upright on Of Course I Still Love You. For the first time a successful and safe landing of a first stage on an Autonomous spaceport drone ship was successful.
After the successful landing, a squad of welders were dropped off on the landing platform, which welded the folding supports on the steel platform, so that the almost 50-meter-high rocket does not tip over in rough seas.
Further missions
May 6, 2016: Successful first-night landing at launch of JCSAT-14 on Of Course I Still Love You. The landing was due to the launch parameters with three engines.
May 27, 2016: further successful landing of the first stage at the start of Thaicom-8 on Of Course I Still Love You. The landing was due to the launch parameters with three engines. On landing, there were minor difficulties. The crumple zone of the Falcon 9 first stage was exploited on one side so far that the rocket tipped on deck. Video footage from a camera on the Falcon 9 was released.
June 15, 2016: First-degree crash landing after the launch of Eutelsat 117 West B / ABS 2A on Of course i still love you. The landing should be done again with three engines, but by reduced output of an engine, there was a hard impact and destroy the stage. The three engines went to maximum power too early, until the stage almost stopped. The fuel went out, then the rocket tipped over, because an outer engine was first under-supplied, and fell from approximately 20 meters height on the Drone ship.
January 14, 2017: Successful first-stage landing at launch of Iridium Next 1 on Just Read the Instructions. When decelerating from 2000 to 1000 m / s before entering the atmosphere, 3 engines were detonated, for landing to achieve a slower deceleration, but only one engine.
June 23, 2017: Successful landing of the first stage at the start of BulgariaSat-1 on Of Course I Still Love You. This landing was due to the launch parameters with three engines. It was also, after the successful reuse of a first stage at the start of SES-10, the second reuse of a first stage and thus the second landing of the same. It was used at the mission on January 14, 2017, making it the first first tier to land on both drone chips.
June 25, 2017: Successful first-stage landing at launch of Iridium Next 2 on Just Read the Instructions. When decelerating from 2000 to 1000 m / s before entering the atmosphere, 3 engines were detonated, for landing to achieve a slower deceleration, but only one engine.
August 24, 2017: Successful first-stage landing at the start of FORMOSAT-5 on Just Read the Instructions.
October 9, 2017: Successful first-stage landing at launch of Iridium Next 3 on Just Read the Instructions.
October 11, 2017: Successful landing of the first stage at the start of SES-11 / EchoStar 105 on Of Course I Still Love You.
October 30, 2017: Successful landing of the first level at the start of Koreasat 5A on Of Course I Still Love You.
February 6, 2018: Crash of the center core of the first Falcon Heavy next to the Of Course I Still Love You. Wreckage of the center core damaged parts of the Spaceport ship.
First successful deployment of a recycled first tier: Mission SES-10 on March 30, 2017
With the resumed first stage of the Falcon 9 of the mission SpaceX CRS-8 on April 8, 2016 succeeded on March 30, 2017 in the mission SES -10 both the transport of the second stage and the payload, the eponymous communications satellite SES-10, into space, as well as a new landing on one of SpaceX’s two autonomous spaceport drone ship, the I Love Love You Course in the Atlantic Ocean. The launch of the rocket was previously from the Kennedy Space Center Launch Complex 39a.
Source from Wikipedia