Editing AS-201

{{short description|1966 uncrewed, suborbital test flight within the Apollo program}}
{{use mdy dates|date=September 2021}}
 {{Infobox spaceflight
 | name = AS-201
 | image = AS-201 launch.jpg
 | image_caption = Launch of AS-201, the first flight of the Apollo spacecraft and Saturn IB launch vehicle
<!-- This flight did NOT have an insignia; DO NOT put back the Apollo Program insignia! -->
| mission_type          = Suborbital test flight
| operator              = [[NASA]]
| mission_duration = 37&nbsp;minutes, 19.7&nbsp;seconds
| suborbital_apogee     = {{convert|265.7|nmi|km|disp=flip|sp=us|abbr=off}}
| suborbital_range      = {{convert|4577|nmi|km|disp=flip|sp=us|abbr=off}}

| spacecraft            = [[Apollo command and service module|Apollo CSM]]-009
| manufacturer          = [[North American Aviation]]
| launch_mass           = {{convert|33,718|lb|kg|disp=flip|sp=us}}
| landing_mass          =

| launch_date           = {{start-date|February 26, 1966, 16:12:01|timezone=yes}}&nbsp;UTC 
| launch_rocket         = [[Saturn IB]] SA-201
| launch_site           = [[Cape Canaveral Air Force Station|Cape Kennedy]] [[Cape Canaveral Air Force Station Launch Complex 34|LC-34]]

| landing_date          = {{end-date|February 26, 1966, 16:49:21|timezone=yes}}&nbsp;UTC 
| landing_site          = South Atlantic Ocean<br/>{{coord|8|56|S|10|43|W|type:event|name=AS-201 splashdown}}
| recovery_by           = {{USS|Boxer|CV-21|6}}
| previous_mission      = [[AS-105]]
| next_mission          = [[AS-203]]
| programme             = [[Apollo program]]
}}

'''AS-201''' (Also known as '''SA-201''', '''Apollo 1-A''', or '''Apollo 1''' prior to the 1967 pad fire,<ref>{{cite web|title=The Apollo Program - Apollo 1 |url=https://www.nasa.gov/mission/apollo-1/ |website=NASA |access-date=May 12, 2025}}</ref> flown February 26, 1966, was the first [[Uncrewed spacecraft|uncrewed]] test flight of an entire production Block I [[Apollo command and service module]] and the [[Saturn IB]] launch vehicle. The spacecraft consisted of the second Block I command module and the first Block I service module. The [[suborbital flight]] was a partially successful demonstration of the service propulsion system and the [[reaction control system]]s of both modules, and successfully demonstrated the capability of the command module's [[heat shield]] to survive re-entry from [[low Earth orbit]].

==Vehicle configuration==

===Spacecraft===
{{Main|Apollo command and service module}}
The command and service module CSM-009 was a Block I version, designed before the [[lunar orbit rendezvous]] method was chosen for the [[Apollo program|Apollo]] lunar landing; therefore it lacked capability to dock with a [[lunar module]]. Block I also employed preliminary designs of certain subsystems, and was heavier than the Block II version with lunar mission capability. All previous command and service modules flown (with one exception) were [[Boilerplate (spaceflight)|boilerplate]] versions.<ref name="AS201post">{{cite report|title=Postlaunch Report for Mission AS-201 (Apollo Spacecraft 009) |url=https://ntrs.nasa.gov/api/citations/19670074061/downloads/19670074061.pdf |date=May 6, 1966 |publisher=NASA |access-date=May 12, 2025}}</ref>

CM-009 was the second production Block I command module to fly, the first being CM-002 flown on a [[Little Joe II]] rocket for the final launch escape system abort test, designated [[A-004]]. CM-009 varied from the production configuration by the omission of the guidance and navigation system; crew couches, displays, and associated equipment; and by the addition of a control programmer and open-loop emergency detection system.

SM-009 was the first production Block I service module to fly. It varied from the production configuration by replacement of the electrical power-generating [[fuel cell]]s with batteries, and omission of the [[Unified S-band|S-band]] communication equipment.

The launch also included a Block I launch escape system (LES), and the first flight of the Spacecraft–LM adapter (SLA) which connected the spacecraft to the launch vehicle.

===Launch vehicle===
{{Main|Saturn IB}}
The Saturn IB was the uprated version of the [[Saturn I]] rocket flown in ten earlier Apollo missions. It featured an upgrade of the first stage (S-IB-1) engines to increase total thrust from {{convert|1,500,000|lbf|kN|abbr=on}} of thrust to {{convert|1,600,000|lbf|kN|abbr=on}}, and replacement of the second stage with the [[S-IVB (rocket stage)|S-IVB]]. This stage used a new [[liquid hydrogen]]-burning [[J-2 (rocket engine)|J-2 engine]] which would also be used on the [[S-II]] second stage of the [[Saturn V]] lunar launch vehicle. A modified version of the S-IVB, with an in-space restartable J-2, would also be used as the third stage of the Saturn V. It also used a new model of the guidance and control system known as the [[Saturn V Instrument Unit|Instrument Unit]], which would also be used on the Saturn V.

==Objectives==
The objectives of the mission were to:
* Demonstrate the Saturn IB launch vehicle propulsion, guidance and electrical systems
* Demonstrate structural compatibility between the launch vehicle and CSM, ensuring the spacecraft's design loads weren't exceeded
* Demonstrate appropriate separation of all vehicle elements
* Demonstrate the CSM's heat shield, service propulsion system (including in-space restart), CM and SM reaction control systems, environmental control of cabin pressure and temperature, partial communications, stability and control, Earth landing system, and electrical power subsystem.
* Evaluate the Emergency Detection System in an [[Open-loop controller|open-loop]] configuration
* Demonstrate the CM heat shield [[Ablation|ablator]] at a 200 BTU/ft<sup>2</sup>/sec heat transfer rate
* Demonstrate support facilities for launch, mission control, and recovery

The mission profile called for the Saturn IB to launch the spacecraft on an east-by-southeast heading into a high ballistic trajectory; then the CSM would separate from the SLA. The service module engine would be fired twice, then the command module would re-enter and land in the south Atlantic Ocean.

==Preparation for flight==
[[File:Saturn Apollo Program (6522248).jpg|thumb|S-IB-1 undergoing a full-duration static firing at [[Marshall Space Flight Center|MSFC]] on April 13, 1965]]
[[File:651220Saturn1Bpropellantloadingtests.jpg|thumb|S-IB-1 undergoing propellant tests for AS-201 on December 20, 1965]]
The first piece of the rocket to arrive at the Cape was the S-IB stage on August 14, 1965, by the barge ''Promise''. It was built by Chrysler and featured eight H-1 engines built by Rocketdyne. The S-IVB second stage arrived next on September 18. The Instrument Unit that would control the launch vehicle arrived October 22, the command module arrived three days later and the service module on October 27.<ref name="moonport">{{cite report|title=Moonport - A History of Apollo Launch Facilities and Operations |first1=Charles D. |last1=Benson |first2=William Barnaby |last2=Faherty |date=1978 |url=https://www.google.com/books/edition/Moonport/BEYCAAAAIAAJ?hl=en&gbpv=1&bsq=barge%20Promise |publisher=NASA |access-date=May 14, 2025}}</ref>{{rp|368-369}}

The first stage was erected at the pad soon after arriving at [[Cape Canaveral Air Force Station|Cape Kennedy]]. The second stage joined it on October 1. After fixing some problems in the Instrument Unit it was mated to the S-IVB on October 25. The CSM was mated on December 26.<ref name="moonport"/>{{rp|369}}

The first problem encountered by NASA came on October 7. The [[RCA 110A]] computer which would test the rocket and thus, automating the process, was ten days behind schedule meaning that it would not be at the Cape before November 1. This meant that by the middle of October little could be done at the pad. When the computer finally did arrive it continued to have problems with the punch cards and also the capacitors that did not operate well under a protective coating. In the end however the testing of the launch vehicle was still on schedule.<ref name="moonport"/>{{rp|349-352, 372}}

Testing was running around the clock during December. Technicians were testing the CSM's fuel systems during the day and the testing was running on the rocket at night.

There was even an instance of a variant of the [[Y2K bug]] in the computer. As it ran past midnight, when the time changed from 2400 to 0001 the computer could not handle it and "turned into a pumpkin" according to an interview with Frank Bryan, a [[Kennedy Space Center]] Launch Vehicle Operations Engineering staff member.<ref name="moonport"/>{{rp|373}}
[[File:APOLLO SPACECRAFT 009 - SATURN 1B 201 - ON PAD - COMPLEX 34 - CAPE (S66-20410).jpg|thumb|Saturn 1B countdown demonstration at [[LC 34]] on February 6, 1966]]
In the end the testing regimen slowly completed and the plugs-out tests were completed proving that the rocket could function by itself.

==Flight==

===Launch attempt===
The first launch attempt was scheduled for February 26, 1966. There were several small delays, but when the pressure in one of the fuel tanks in the S-IVB fell below the allowed limits, the onboard computer aborted the launch four seconds before launch.<ref name="moonport"/>{{rp|375-377}}

Though the problem could be fixed easily, it was thought that it could not be done within the launch window. After running a simulated launch and 150 seconds of flight to show that the rocket could operate with the lower pressure in the fuel tank, the launch was reinstated.<ref name="moonport"/>{{rp|375-377}}

===Flight===
Finally, after months of delays and problems, the first flight of the Saturn IB lifted off from Pad 34. The first stage worked perfectly, lifting the rocket to {{convert|57|km|nmi|sp=us}}, when the S-IVB took over and lifted the spacecraft to {{convert|425|km|nmi|sp=us}}. The CSM separated and continued upwards to {{convert|488|km|nmi|sp=us}}.<ref name="AS201vid">{{cite AV media | url=https://www.youtube.com/watch?v=V5n6td7JFb0 |title=AS-201 - First Saturn IB Launch - Apollo Test Flight |date=February 26, 1966 |website=youtube.com |access-date=May 12, 2025}}</ref>

The CSM then fired its own rocket to accelerate the spacecraft towards Earth. The first burn lasted for 184 seconds. It then fired later for ten seconds. This proved that the engine could restart in space, a crucial part of any crewed flight to the Moon.

It entered the atmosphere traveling {{convert|8300|m/s|ft/s|sp=us}}. It [[splashdown (spacecraft landing)|splashed down]] 37 minutes after launch, {{convert|72|km|nmi|sp=us}} from the planned touch down point, and was on board the [[aircraft carrier]] {{USS|Boxer|CV-21|6}} two hours later.<ref>{{cite web |archive-url=https://web.archive.org/web/20020616023612/http://nssdc.gsfc.nasa.gov/database/MasterCatalog?sc=APST201 |url=http://nssdc.gsfc.nasa.gov/database/MasterCatalog?sc=APST201 |title=AS-201 NSSDC ID:APST201 |website=NASA |archive-date=June 16, 2002|access-date=May 12, 2025}}</ref>

==Problems==
[[Image:AS201 Command Module.jpg|right|thumb|AS-201 CM-009 exhibited at the Strategic Air and Space Museum.]]
There were three problems encountered on the flight. The service module engine worked properly for only 80 seconds, interrupted by the presence of [[helium]] pressurant gas in the combustion chamber. Helium was used to pressurize the fuel tanks but should not have been in the combustion chamber. This was caused by a break in an [[oxidizer]] line that allowed helium to mix with the oxidizer.

The second problem was an electrical system failure which caused the command module to lose steering control during reentry. Last, measurements that were intended to be taken during reentry, failed due to a short circuit.<ref>{{cite web|title=Heat Shield, Fragment, Ablated, Apollo CM 009 |url=https://airandspace.si.edu/collection-objects/heat-shield-fragment-ablated-apollo-cm-009/nasm_A19731423003 |website=National Air & Space Museum |access-date=May 12, 2025}}</ref> Both of these problems were found to be due to incorrect wiring, and were easily fixed.

==Capsule location==
After the flight the capsule was also used for drop tests at [[White Sands Missile Range]]. It is now on display at the [[Strategic Air and Space Museum]], [[Ashland, Nebraska]].<ref>{{cite web|title=55 Years Ago: Apollo AS-201 Test Flight |first=John |last=Uri |url=https://www.nasa.gov/history/55-years-ago-apollo-as-201-test-flight/ |website=NASA |date=March 1, 2001 |access-date=May 12, 2025}}</ref>

==See also==
{{Portal|Spaceflight}}
*[[Splashdown]]

==References==
{{Reflist}}

==External links==
{{Commons category}}
*[http://www.hq.nasa.gov/office/pao/History/SP-4205/cover.html Chariots for Apollo: A History of Manned Lunar Spacecraft] {{Webarchive|url=https://web.archive.org/web/20151020095653/http://www.hq.nasa.gov/office/pao/History/SP-4205/cover.html |date=October 20, 2015 }}

{{Include-NASA}}
{{Apollo program|state=expanded}}
{{NASA space program}}

{{Use American English|date=January 2014}}

[[Category:Apollo program missions|Apollo 02]]
[[Category:1966 in spaceflight]]
[[Category:Spacecraft launched by Saturn rockets]]
[[Category:Saturn IB]]