Splashdown Explained

Splashdown is the method of landing a spacecraft or launch vehicle in a body of water, usually by parachute. This has been the primary recovery method of American capsules including NASA’s Mercury, Gemini, Apollo and Orion along with the private SpaceX Dragon. It is also possible for the Boeing Starliner, Russian Soyuz, and the Chinese Shenzhou crewed capsules to land in water in case of contingency. NASA recovered the Space Shuttle solid rocket boosters (SRBs) via splashdown, as is done for Rocket Lab's Electron first stage.

As the name suggests, the vehicle parachutes into an ocean or other large body of water. Due to its low density and viscosity, water cushions the spacecraft enough that there is no need for a braking rocket to slow the final descent as is the case with Russian and Chinese crewed space capsules or airbags as is the case with the Starliner.^[1]

The American practice came in part because American launch sites are on the coastline and launch primarily over water.^[2] Russian launch sites such as Baikonur Cosmodrome are far inland, and most early launch aborts would descend on land.

History

The splashdown method of landing was used for Mercury, Gemini and Apollo (including Skylab, which used Apollo capsules). Soyuz 23 unintentionally landed on a freezing lake with slushy patches of ice during a snowstorm.^{[3] [4]}

On early Mercury flights, a helicopter attached a cable to the capsule, lifted it from the water and delivered it to a nearby ship. This was changed after the sinking of Liberty Bell 7. All later Mercury, Gemini and Apollo capsules had a flotation collar (similar to a rubber life raft) attached to the spacecraft to increase their buoyancy. The spacecraft would then be brought alongside a ship and lifted onto deck by crane.

After the flotation collar is attached, a hatch on the spacecraft is usually opened. At that time, some astronauts decide to be hoisted aboard a helicopter for a ride to the recovery ship and some decided to stay with the spacecraft and be lifted aboard ship via crane. All Gemini and Apollo flights (Apollos 7 to 17) used the former, while Mercury missions from Mercury 6 to Mercury 9, as well as all Skylab missions and Apollo-Soyuz used the latter, especially the Skylab flights as to preserve all medical data. During the Gemini and Apollo programs, NASA used for the astronauts to practice water egress.

Apollo 11 was America's first Moon landing mission and marked the first time that humans walked on the surface of another planetary body. The possibility of the astronauts bringing pathogens from the Moon back to Earth was remote, but not ruled out. To contain any possible contaminants at the scene of the splashdown, the astronauts donned special Biological Isolation Garments and the outside of the suits were scrubbed prior to the astronauts being hoisted aboard and escorted safely inside a Mobile Quarantine Facility.^[5] Both the SpaceX Dragon 1 and Dragon 2 capsules were designed to use the splashdown method of landing. The original cargo Dragon splashed down in the Pacific Ocean off the coast of Baja California. At the request of NASA, both the crew and cargo variations of the Dragon 2 capsule splash down off the coast of Florida, either in the Atlantic Ocean or the Gulf of Mexico.^{[6] [7]}

The early design concept for Orion (then known as the Crew Exploration Vehicle) featured recovery on land using a combination of parachutes and airbags, although it was also designed to make a contingency splashdown if needed. Due to weight considerations, the airbag design concept was dropped for Orion, and it conducts landings via splashdown in the Pacific Ocean off the coast of California.^[8]

Disadvantages

Perhaps the most dangerous aspect is the possibility of the spacecraft flooding and sinking. For example, when the hatch of Gus Grissom's Liberty Bell 7 capsule blew prematurely, the capsule sank and Grissom almost drowned. Since the spacecraft's flooding will occur from a location in its hull where it ruptures first, it is important to determine the location on the hull that experiences the highest loading.^[9] This location along the impacting side is determined by the surrounding `air cushion' layer, which deforms the water surface before the moment of impact, and results in a non-trivial geometry of the liquid surface during first touch-down.^{[10] [11] [12]} Soyuz 23 was dragged under a frozen lake by its parachutes. The crew became incapacitated by carbon dioxide and were rescued after a nine-hour recovery operation.^[13]

If the capsule comes down far from any recovery forces, the crew may be stranded at sea for an extended period of time. As an example, Scott Carpenter in Aurora 7 overshot the assigned landing zone by 400km (200miles). These recovery operation mishaps can be mitigated by placing several vessels on standby in different locations, but this can be an expensive option.

Exposure to saltwater can have adverse effects on vehicles intended for reuse, such as Dragon.^[14]

Launch vehicles

Some reusable launch vehicles recover components via splashdown. This was first seen with the Space Shuttle SRBs, with STS-1 launching in 1981. Out of 135 launches, NASA recovered all but two sets of SRBs.^[15]

SpaceX has conducted propulsive splashdowns of the Falcon 9 first stage, Super Heavy booster, and Starship spacecraft. These vehicles are designed to land on land or modified barges and do not always survive intact after tipping over in the water; SpaceX has mainly conducted propulsive splashdowns for development flights. After the launch of CRS-16, the booster experienced a control issue and splashed down in the ocean instead of making an intended landing at Landing Zone 1.^[16]

Rocket Lab intended to catch the first stage of their Electron rocket with a helicopter as it descended under parachute, but abandoned this idea in favor of parachute splashdown. In 2020, Rocket Lab made their first booster recovery.^[17]

List of spacecraft splashdowns

Crewed spacecraft

	Spacecraft	Agency	Landing date	Coordinates	Recovery ship	Miss distance (km)	Reference
1	Freedom 7	NASA	May 5, 1961	27.2283°N -128°W		5.6km (03.5miles)	[18]
2	Liberty Bell 7	NASA	July 21, 1961	27.5333°N -119°W		9.3km (05.8miles)	[19]
3	Friendship 7	NASA	February 20, 1962	21.4333°N -109°W	(USS Randolph**)	74	[20]
4	Aurora 7	NASA	May 24, 1962	19.45°N -122°W	(**)	400	[21]
5	Sigma 7	NASA	October 3, 1962	32.1°N -202°W		7.4	[22]
6	Faith 7	NASA	May 16, 1963	27.3333°N -202°W	USS Kearsarge	8.1	[23]
7	Gemini 3	NASA	March 23, 1965	22.4333°N -121°W	USS Intrepid	111	[24]
8	Gemini 4	NASA	June 7, 1965	27.7333°N -85°W		81	[25]
9	Gemini 5	NASA	August 29, 1965	29.7333°N -114°W	USS Lake Champlain	270	[26]
10	Gemini 7	NASA	December 18, 1965	25.4167°N -77°W	USS Wasp	12	[27]
11	Gemini 6A	NASA	December 16, 1965	23.5833°N -117°W	USS Wasp	13	[28]
12	Gemini 8	NASA	March 17, 1966	25.2333°N 136°W	(**)	2	[29]
13	Gemini 9A	NASA	June 6, 1966	27.8667°N -75°W	USS Wasp	0.7	[30]
14	Gemini 10	NASA	July 21, 1966	26.75°N -128°W		6	[31]
15	Gemini 11	NASA	September 15, 1966	24.25°N -70°W		5	[32]
16	Gemini 12	NASA	November 15, 1966	24.5833°N -126°W	USS Wasp	5	[33]
17	Apollo 7	NASA	October 22, 1968	27.5333°N -68°W		3	[34]
18	Apollo 8	NASA	December 27, 1968	8.125°N -166.2°W		2	[35]
19	Apollo 9	NASA	March 13, 1969	23.25°N -123°W	USS Guadalcanal	5	[36] [37]
20	Apollo 10	NASA	May 26, 1969	-15.0333°N -203°W		2.4	[38] [39]
21	Apollo 11	NASA	July 24, 1969	13.3167°N -178°W		3.13	[40] [41]
22	Apollo 12	NASA	November 24, 1969	-15.7833°N -174°W	USS Hornet	3.7	[42] [43]
23	Apollo 13	NASA	April 17, 1970	-21.6333°N -187°W		1.85	[44] [45]
24	Apollo 14	NASA	February 9, 1971	-27.0167°N -211°W		1.1	[46] [47]
25	Apollo 15	NASA	August 7, 1971	26.1167°N -166°W		1.85	[48] [49]
26	Apollo 16	NASA	April 27, 1972	-0.7167°N -169°W		0.55	[50] [51]
27	Apollo 17	NASA	December 19, 1972	-17.8833°N -173°W	USS Ticonderoga	1.85	[52] [53]
28	Skylab 2	NASA	June 22, 1973	24.75°N -129°W	USS Ticonderoga		[54]
29	Skylab 3	NASA	September 25, 1973	30.7833°N -149°W	USS New Orleans		[55]
30	Skylab 4	NASA	February 8, 1974	31.3°N -167°W	USS New Orleans
31	Apollo CSM-111	NASA	July 24, 1975	22°N -163°W	USS New Orleans	1.3	[56] [57]
32	Soyuz 23	USSR	October 16, 1976	Lake Tengiz	Mi-8 helicopter		[58]
33	Crew Dragon Demo-2	SpaceX	August 2, 2020	29.8°N -117°W	GO Navigator		[59]
33	Crew Dragon Crew-1	SpaceX	May 2, 2021	29.5333°N -97°W	GO Navigator		[60]
34	Inspiration4	SpaceX	September 18, 2021		GO Searcher		[61]
35	Crew Dragon Crew-2	SpaceX	November 7, 2021		GO Navigator
35	Axiom Mission 1	SpaceX	April 25, 2022		Megan
36	Crew Dragon Crew-3	SpaceX	May 6, 2022		Shannon		[62]
37	Crew Dragon Crew-4	SpaceX	October 14, 2022		Megan
38	Crew Dragon Crew-5	SpaceX	March 11, 2023		Shannon
39	Axiom Mission 2	SpaceX	May 31, 2023		Megan
40	Polaris Dawn	SpaceX	Sep 15, 2024

Uncrewed spacecraft

Spacecraft	Agency	Landing date	Coordinates	Recovery ship	Miss distance
Jupiter AM-18 (Able and Baker)	USAF	May 28, 1959	48to N Antigua Island		16km (10miles)[63]
Mercury-Big Joe	NASA	September 9, 1959	2407km (1,496miles) SE Cape Canaveral		925km (575miles)[64]
Mercury-Little Joe 2Sam The Rhesus Monkey	NASA	December 4, 1959	319km (198miles) SE Wallops Island, Virginia		? km[65]
Mercury-Redstone 1A	NASA	December 19, 1960	378.2km (235miles) SE Cape Canaveral		12.9km (08miles)[66]
Mercury-Redstone 2	NASA	January 31, 1961	675.9km (420miles) SE Cape Canaveral	[67]	209.2km (130miles)[68]
Mercury-Atlas 2	NASA	February 21, 1961	2293.3km (1,425miles) SE Cape Canaveral	USS Donner	20.9km (13miles)[69]
Discoverer 25 (Corona 9017)	USAF	June 16, 1961			mid-air recovery missed
Mercury-Atlas 4	NASA	September 13, 1961	257.5km (160miles) E of Bermuda		64.4km (40miles)[70]
Mercury-Atlas 5	NASA	November 29, 1961	804.7km (500miles) SE of Bermuda		? km[71]
Gemini 2	NASA	January 19, 1965	16.565°N -95.27°W 3423.1km (2,127miles) downrange from KSC	USS Lake Champlain	38.6km (24miles)[72]
AS-201	NASA	February 26, 1966	-8.18°N -11.15°W 8472km (5,264miles) downrange from KSC	USS Boxer	? km
AS-202	NASA	August 25, 1966	16.12°N 168.9°W 804.7km (500miles) southwest of Wake Island	USS Hornet	? km[73]
Gemini 2-MOL	USAF	November 3, 1966	8149.7km (5,064miles) SE KSC near Ascension Island		11.26km (07miles)[74]
Apollo 4	NASA	November 9, 1967	30.1°N -172.53°W		16km (10miles)
Apollo 6	NASA	April 4, 1968	27.6667°N -216°W	USS Okinawa	? km
Zond 5	USSR	September 21, 1968	-32.63°N 65.55°W	USSR recovery naval vessel and	105km (65miles)[75] [76]
Zond 8	USSR	October 27, 1970	730km (450miles) SE of the Chagos Archipelago, Indian Ocean	USSR recovery ship	24 km[77] [78]
Cosmos 1374	USSR	June 4, 1982	-17°N 98°W 560km (350miles) S of Cocos Islands, Indian Ocean	USSR recovery ship	? km
Cosmos 1445	USSR	March 15, 1983	556km (345miles) S of Cocos Islands, Indian Ocean	USSR recovery ship	? km
Cosmos 1517	USSR	December 27, 1983	near Crimea, Black Sea	USSR recovery ship	? km
Cosmos 1614	USSR	December 19, 1984	? km W of the Crimea, Black Sea	USSR recovery ship	? km
COTS Demo Flight 1	SpaceX	December 8, 2010	800km (500miles) west of Baja California, Mexico, Pacific Ocean	?	0.8km (00.5miles)[79]
Dragon C2+	SpaceX	May 31, 2012	26.92°N -120.7°W	?	?[80]
CRS SpX-1	SpaceX	October 28, 2012	?	American Islander[81]	?[82]
CRS SpX-2	SpaceX	March 27, 2013	?	American Islander	?[83]
Exploration Flight Test 1	NASA	December 5, 2014	23.6°N -116.4°W, 275miles west of Baja California
Crew Dragon Demo-1	SpaceX	March 8, 2019	In the Gulf of Mexico, off the coast of Pensacola, Florida	GO Searcher
SpaceX CRS-21	SpaceX	January 14, 2020	In the Gulf of Mexico, off the coast of Tampa, Florida	GO Navigator
Artemis I	NASA	December 11, 2022	Pacific Ocean, west of Baja California	USS Portland	4 nm
IFT-4	SpaceX	June 6, 2024	Indian Ocean
IFT-5	SpaceX	October 13, 2024	Indian Ocean
IFT-6	SpaceX	November 19, 2024	Indian Ocean

See also

• Apollo program
• Apollo–Soyuz Test Project
• Helicopter 66
• Project Gemini
• Project Mercury
• Skylab
• SpaceX Dragon 1
• SpaceX Dragon 2
• Water landing
• Zond program

Notes and References

1. Web site: Tous . Marcos . The science behind splashdown—aerospace engineer explains how NASA and SpaceX get spacecraft safely back . 28 June 2024. The Conversation . 27 November 2024.
2. Web site: Launch Services Program Launch Sites . NASA . 2009-05-14 . 2020-08-07.
3. Archived at Ghostarchive and the Wayback Machine: Web site: The Accidental Spacecraft Splashdown Which Almost Killed Its Crew. www.youtube.com.
4. Web site: Soyuz-23, Lands On A Frozen Lake . VideoCosmos . 2012-06-21 . dead . https://web.archive.org/web/20120414220743/http://www.videocosmos.com/soyuz23.shtm . 2012-04-14 .
5. Web site: Apollo 11 & 12 Recovery . Bob Fish . USS Hornet Museum's website.
6. News: Cargo Dragon heads for splashdown off Florida's west coast. Spaceflight Now. Stephen. Clark. 12 January 2021. 14 January 2021.
7. Web site: AUDIT OF COMMERCIAL RESUPPLY SERVICES TO THE INTERNATIONAL SPACE STATION. https://ghostarchive.org/archive/20221009/https://oig.nasa.gov/docs/IG-18-016.pdf . 2022-10-09 . live.
8. Web site: Solar System Exploration: News & Events: News Archive: NASA Announces Key Decision For Next Deep Space Transportation System . https://web.archive.org/web/20110703185450/http://solarsystem.nasa.gov/news/display.cfm?News_ID=37403 . dead . 2011-07-03 . Solarsystem.nasa.gov . 2011-05-24 . 2012-06-21.
9. Jain. U.. et al.. Journal of Fluid Mechanics. 2021. 938. 4. Air entrapment and its effect on pressure impulses in the slamming of a flat disc on water . A31 . 10.1017/jfm.2021.846. 2012.10137.
10. Jain. U.. et al.. Physical Review Fluids. 2021. 6. 4. Air-cushioning effect and Kelvin-Helmholtz instability before the slamming of a disk on water . L042001 . 10.1103/PhysRevFluids.6.L042001. 2106.09551.
11. Verhagen. J.H.G. Journal of Ship Research. 1967. The Impact of a Flat Plate on a Water Surface.
12. Asryan . N.G.. Izv. Akad. Nauk Arm. SSR Mekh. 1972. Solid plate impact on surface of incompressible fluid in the presence of a gas layer between them.
13. Web site: Carbon Dioxide (CO2) OCHMO-TB-004 Rev C . NASA . 27 November 2024.
14. Web site: NASA. 4-5. A FRAMEWORK FOR ASSESSING THE REUSABILITY OF HARDWARE (REUSABLE ROCKET ENGINES . 11 November 2024.
15. Web site: Gebhardt . Chris . 8 July 2012. One year on – Review notes superb performance of STS-135’s SRBs . NASA Spaceflight . 27 November 2024.
16. Web site: Bergin . Chris . 13 January 2019. CRS-16 Dragon returns to Earth following ISS departure . NASA Spaceflight . 27 November 2024.
17. Web site: Coldewey . Devin . Rocket Lab makes its first booster recovery after successful launch . TechCrunch . 19 November 2020. 27 November 2024.
18. Ezell (1988) p. 143
19. Ezell (1988) p. 144
20. Ezell, Volume II, p. 145
21. Ezell, Volume II, p. 146
22. Ezell, Volume II, p. 147
23. Ezell, Volume II, p. 148
24. Ezell, Volume II, p. 159
25. Ezell, Volume II, p. 160
26. Ezell, Volume II, p. 161
27. Ezell, Volume II, p. 162
28. Ezell, Volume II, p. 163
29. Ezell, Volume II, p. 164
30. Ezell, Volume II, p. 165
31. Ezell, Volume II, p. 166
32. Ezell, Volume II, p. 167
33. Ezell, Volume II, p. 168
34. Ezell, Volume II, p. 188
35. Ezell, Volume II, p. 189
36. Ezell, Volume III, p. 83
37. Orloff, p. 58
38. Ezell, Volume III, p. 84
39. Orloff, p. 78
40. Ezell, Volume III, p. 85
41. Orloff, p. 98
42. Ezell, Volume III, p. 86
43. Orloff, p. 120
44. Ezell, Volume III, p. 87
45. Orloff, p. 143
46. Ezell, Volume III, p. 88
47. Orloff, p. 168
48. Ezell, Volume III, p. 89
49. Orloff, p. 197
50. Ezell, Volume III, p. 91
51. Orloff, p. 225
52. Ezell, Volume III, p. 92
53. Orloff, p. 251
54. Ezell, Volume III, p. 104
55. Ezell, Volume III, p. 105
56. Ezell, Volume III, p. 112
57. https://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/19780009147_1978009147.pdf "ASTP Apollo Miss Distance"
58. News: Cosmonauts Land in Lake, Blizzard . The Milwaukee Journal . October 18, 1976 . UPI.
59. News: NASA Astronauts in SpaceX Capsule Make First Water Landing Since 1975 . The New York Times . August 2, 2020.
60. News: SpaceX Dragon splashes down in Gulf of Mexico, bringing 4 astronauts home . Orlando Sentinel . May 2, 2021.
61. News: SpaceX capsule returns four civilians from orbit, capping off first tourism mission . . September 18, 2021.
62. Web site: Jackie Wattles . SpaceX's wildly busy year continues with astronaut splashdown . 2022-05-06 . CNN.
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64. Web site: Big Joe Shot . nasa.gov . August 9, 2018.
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67. Web site: USS Donner LSD20 . Homestead.com . 2012-06-21.
68. News: Chimp Survives Space Shot . The Milwaukee Sentinel . Associated Press . February 1, 1961.
69. News: Space Capsule Soars 107 Miles High . Associated Press . The Florence Times . Florence, Alabama . February 21, 1961.
70. News: U.S. Robot Orbited, Returned . Meriden Journal . September 13, 1961.
71. News: Capsule Trouble Forces Early Landing Of Craft . Associated Press . Toledo, Ohio . Toledo Blade . November 29, 1961.
72. https://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/19650018359_1965018359.pdf "Gemini 2 Distance traveled, Landing Point, Miss Distance"
73. Web site: Apollo-Saturn Unmanned Missions. Cheryl L.. Mansfield. January 9, 2018. NASA.
74. News: Titan 3 Gives Spectacular Space Show . Sarasota, Florida . Sarasota Journal . November 3, 1966.
75. Book: Michael Cassutt. Red Moon. 2007. Tom Doherty Associates. 978-1-4299-7172-0. 320.
76. https://sse.jpl.nasa.gov/missions/profile.cfm?Sort=Alpha&Alias=Zond%2005&Letter=Z&Display=ReadMore "Zond 5, Landing Point, Miss Distance"
77. Book: Brian Harvey. Soviet and Russian Lunar Exploration. 2007. Springer Science & Business Media. 978-0-387-73976-2. 218.
78. https://sse.jpl.nasa.gov/missions/profile.cfm?Sort=Chron&MCode=Zond_08&StartYear=1970&EndYear=1979&Display=ReadMore "Zond 8, Landing Point"
79. Web site: "COTS 1 (SpaceX Dragon 1), Splashdown area". https://web.archive.org/web/20101210214816/http://www.spacex.com/press.php?page=20101208. dead. December 10, 2010.
80. Web site: History is made as Dragon splashes down safely in the Pacific! | Bad Astronomy | Discover Magazine . Blogs.discovermagazine.com . 2012-06-21 . dead . https://web.archive.org/web/20120705041532/http://blogs.discovermagazine.com/badastronomy/2012/05/31/history-is-made-as-dragon-splashes-down-safely-in-the-pacific/ . 2012-07-05 .
81. Web site: American Island . marinetraffic.com . August 9, 2018.
82. Web site: Dragon Returns to Earth . NASA. 2012-10-28 . 2012-10-29.
83. Web site: SpaceX brings home Dragon with 2,700 pounds of cargo. Spaceflightnow. 2013-03-26 . 2013-03-27.