Skylab

Skylab as photographed by its departing final crew
Station statistics
COSPAR ID	1973-027A
Call sign	Skylab
Crew	3 (9 overall)
Launch	May 14, 1973 17:30:00 UTC
Launch pad	LC-39A, Kennedy Space Center
Reentry	July 11, 1979 16:37:00 UTC near Perth, Australia
Mass	169,950 lb (77,088 kg)[1] w/o CSM
Length	86.3 feet (26.3 m) w/o CSM
Width	55.8 feet (17.0 m) w/ one solar panel
Height	24.3 feet (7.4 m) w/ telescope mount
Diameter	21.67 feet (6.6 m)
Pressurised volume	319.8 m3 (11,290 cu ft) w/ docking adapter and airlock)
Perigee	269.7 mi (434.0 km)
Apogee	274.6 mi (441.9 km)
Orbital inclination	50°
Orbital period	93.4 min
Orbits per day	15.4
Days in orbit	2,249 days
Days occupied	171 days
Number of orbits	34,981
Distance travelled	~890,000,000 mi 1,400,000,000 km
Statistics as of Re-entry July 11, 1979

Skylab was a space station launched and operated by NASA, the space agency of the United States. Skylab orbited the Earth from 1973 to 1979, and included a workshop, a solar observatory, and other systems. It was launched unmanned by a modified Saturn V rocket, with a mass of 169,950 pounds (77 t).^[1] Three manned missions to the station, conducted between 1973 and 1974 using the Apollo Command/Service Module (CSM) atop the smaller Saturn IB, each delivered a three-astronaut crew. On the third mission, an additional Apollo / Saturn IB stood by, ready for launch if needed to rescue the crew in orbit.

Skylab included an Apollo Telescope Mount (a multi-spectral solar observatory), Multiple Docking Adapter with two docking ports, Airlock Module with EVA hatches, and the Orbital Workshop, the main habitable volume of the station. Power came from solar arrays, as well as fuel cells in the docked Apollo CSM. The rear of the station included a large waste tank, propellant tanks for maneuvering jets, and a heat radiator.

The station was damaged at launch when the micrometeoroid shield separated from the station and tore away, depriving the station of most of its power, removing protection from intense solar heating, and threatening to make the station unusable. The first crew was able to save it in the first ever in-space major repair, by deploying a replacement heat shade and freeing the single remaining, jammed main solar array.

Numerous scientific experiments were conducted aboard Skylab during its operational life, and crews were able to confirm the existence of coronal holes in the Sun. The Earth Resources Experiment Package (EREP), was used to view the Earth with sensors that recorded data in the visible, infrared, and microwave spectral regions. Thousands of photographs of Earth were taken, and records for human time spent in orbit were extended.

Plans were made to refurbish and reuse Skylab, using the Space Shuttle to boost its orbit and repair it. However, development of the Shuttle was delayed, and Skylab reentered Earth's atmosphere and disintegrated in 1979, with debris striking portions of Western Australia.

After Skylab's demise, the focus shifted to the reusable Spacelab module, an orbital workshop that could be deployed from the Space Shuttle and returned to Earth. The next American space station project was Space Station Freedom, which was never completed, although it eventually led to the construction of the US Orbital Segment of the International Space Station, starting in 1998. Shuttle-Mir was another project, and led to the U.S. funding Spektr, Priroda, and the Mir Docking Module in the 1990s.

Background[link]

The exact origin of the project is difficult to pinpoint because a number of different but related proposals were developed by various government agencies before Skylab itself was launched.

Early studies[link]

A key event took place in 1959, when rocket scientist and space architect Wernher von Braun, then head of the Development Operations Division at the Army Ballistic Missile Agency, submitted his final Project Horizon plans to the U.S. Army. The overall goal of Horizon was to place a human on the Moon, a mission that would soon be taken over by the rapidly forming NASA. Although concentrating on the Moon missions, von Braun also detailed an orbiting laboratory built out of an Horizon upper stage,^[2]:23 an idea used for Skylab.^[2]:9

A number of NASA centers studied various space station designs in the early 1960s. Studies generally looked at platforms launched by the Saturn V, followed up by crews launched on Saturn IB using an Apollo Command/Service Module,^[2]:10 or a Gemini capsule^[2]:14 on a Titan II-C, the latter being much less expensive in the case where cargo was not needed. Proposals ranged from an Apollo-based station with two to three men, or a small "canister" for four men with Gemini capsules resupplying it, to a large, rotating station with 24 men and an operating lifetime of about five years.^[2]:13-14 A proposal to study the use of a Saturn S-IV as a manned space laboratory was documented in 1962 by the Douglas Aircraft Company.^[3]

Air Force competition[link]

In September 1963, NASA and the Department of Defense (DoD) agreed to cooperate in building a space station.^[2]:17 In December, the US Air Force nonetheless announced Manned Orbital Laboratory (MOL), a small space station primarily intended for photo reconnaissance using large telescopes directed by a two-man crew. The station was the same diameter as a Titan II upper stage, and would be launched with the crew riding atop in a modified Gemini capsule with a hatch cut into the heat shield on the bottom of the capsule.^{[2]:17-19[4][5]} MOL competed for funding with a NASA station for the next five years,^[2]:15 and led to changes being made to the NASA plans, so that they would resemble MOL less.^[2]:17

Development[link]

Apollo Applications Program[link]

After landing on the moon in 1969, NASA management was concerned about losing the 400,000 workers involved in Apollo.^[2]:20,22 It set up the Apollo Logistic Support System Office, originally intended to study various ways to modify the Apollo hardware for scientific missions. The office initially proposed a number of projects for direct scientific study, including an extended-stay lunar mission which required two Saturn V launchers, a "lunar truck" based on the Lunar Module (LEM), a large manned solar telescope using an LEM as its crew quarters, and small space stations using a variety of LEM or CSM-based hardware. Although it did not look at the space station specifically, over the next two years the office would become increasingly dedicated to this role. In August 1965, the office was renamed, becoming the Apollo Applications Program (AAP).^[2]:20

As part of their general work, in August 1964 the Manned Spacecraft Center (MSC) presented studies on an expendable lab known as Apollo "X", short for Apollo Extension System. "Apollo X" would have replaced the LEM carried on the top of the S-IVB stage with a small space station slightly larger than the CSM's service area, containing supplies and experiments for missions between 15 and 45 days' duration. Using this study as a baseline, a number of different mission profiles were looked at over the next six months.

Wet workshop[link]

Dr. von Braun's sketch of a Space Station based on conversion of a Saturn V stage, 1964.

Wernher von Braun proposed a more ambitious plan to build a much larger station. His design replaced the S-IVB third stage of a complete Saturn V with an aeroshell, primarily as an adapter for the CSM on top. Inside the shell was a cylindrical equipment section slightly smaller in diameter than the CSM. On reaching orbit, the S-II second stage would be vented to remove any remaining hydrogen fuel, then the equipment section would be slid into it via a large inspection hatch. The station filled the entire interior of the S-II stage's hydrogen tank, with the equipment section forming a "spine" and living quarters between it and the walls of the booster. This would have resulted in a very large 33-by-45-foot (10.1 by 13.7 m) living area. Power was to be provided by solar cells lining the outside of the S-II stage.^[2]:22

One problem with this proposal was that it required a dedicated Saturn V launch to fly the station. At the time the design was being proposed, all of the then-contracted Saturn Vs were already earmarked for Moon missions. However, several planned Earth-orbit test missions for the LEM and CSM had been canceled, leaving a number of Saturn IBs free for use. Further work led to the idea of building a smaller station based on the S-IVB instead, launching it on a surplus Saturn IB.

Since the Saturn I had a much lower payload capability than the Saturn V, the S-IV stage could not be left empty; its thrust would be needed for the mission. This limitation led to the development of the "wet workshop" concept, which led naturally out of von Braun's idea of using an existing stage after its fuel had burned off. However, in this case the station was to be built out of the S-IVB stage itself, as opposed to the S-II below it. A number of S-IVB-based stations were studied at MSC, but even the earliest, from mid-1965, had much in common with the Skylab design that actually flew. An airlock would be attached to the hydrogen tank, in the area where the LEM would sit on a lunar mission, and a minimum amount of equipment would be installed in the tank itself in order to avoid taking up too much fuel volume. Floors of the station would be made from an open metal framework that allowed the fuel to flow through it. After launch, a follow-up mission launched by a Saturn IB would launch additional equipment, including solar panels, an equipment section and docking adapter, and various experiments. Douglas Aircraft, builder of the S-IVB stage, was asked to prepare proposals along these lines. The company had for several years been proposing stations based on the S-IV stage, before it was replaced by the S-IVB.^[2]:25

An early "wet workshop" version of Skylab.

On 1 April 1966, MSC sent out contracts to Douglas, Grumman, and McDonnell for the conversion of a S-IVB spent stage, under the name Saturn S-IVB spent-stage experiment support module (SSESM).^[2]:30 In May, astronauts voiced concerns over the purging of the stage's hydrogen tank in space. Nevertheless, in late July it was announced that the Orbital Workshop would be launched as a part of Apollo mission AS-209, originally one of the Earth-orbit CSM test launches, followed by two Saturn I/CSM crew launches, AAP-1 and AAP-2.

MOL remained AAP's chief competitor for funds, although the two programs cooperated on technology. NASA considered flying experiments on MOL, or using its Titan IIIC booster instead of the much more expensive Saturn IB. But they decided that the Air Force station was not large enough, and that converting Apollo hardware for use with Titan would be too slow and too expensive.^[2]:45-48 The DoD later canceled MOL in June 1969.^[2]:109

Dry workshop[link]

Design work continued over the next two years, in an era of shrinking budgets.^[6] In August 1967, NASA announced that the lunar mapping and base construction missions examined by the AAP were being canceled. Only the Earth-orbiting missions remained, namely the Orbital Workshop and Apollo Telescope Mount solar observatory.

Later, several Moon missions were canceled as well, originally to be Apollo missions 18 through 20. The cancellation of these missions freed up three Saturn V boosters for the AAP program. Although this would have allowed them to develop von Braun's original S-II based mission, by this time so much work had been done on the S-IV based design that work continued on this baseline. With the extra power available, the wet workshop was no longer needed;^[2]:109-110 the S-IC and S-II lower stages could launch a "dry workshop", with its interior already prepared, directly into orbit.

Habitability[link]

Illustrated cutaway of main interior

A dry workshop simplified plans for the interior of the station.^[2]:130 Industrial design firm Raymond Loewy/William Snaith recommended emphasizing habitability and comfort for the astronauts by, for example, providing a wardroom for meals and relaxation,^[2]:133-134 and a window to view the Earth and space, although astronauts who participated in Skylab planning were dubious about the designers' focus on areas such as color schemes.^[2]:137 Habitability had not previously been an area of concern when building spacecraft, due to their small volume and brief mission durations, but the Skylab missions would last for months.^[2]:133 NASA sent a scientist on Jacques Piccard's Ben Franklin submarine in the Gulf Stream in July and August 1969, to learn how six people would live in an enclosed space for four weeks.^[2]:139-140

Astronauts were uninterested in watching movies on a proposed entertainment center or playing games, but did want books and individual music choices.^[2]:137 Food was also important; early Apollo crews complained about its quality, and a NASA volunteer found living on the Apollo food for four days on Earth to be intolerable; its taste and composition, in the form of cubes and squeeze tubes, were unpleasant. Skylab food significantly improved on its predecessors by prioritizing edibility over scientific needs.^[2]:141-142

Each astronaut had a private sleeping area the size of a small walk-in closet, with a curtain, sleeping bag, and locker.^[7]:82 Designers also added a shower^{[2]:139[7]:80} and a toilet;^{[2]:152-158[7]:30} the latter was both for comfort and to obtain precise urine and feces samples for examination on Earth.^[2]:165

Operational history[link]

Completion and launch[link]

Launch of the modified Saturn V rocket carrying the Skylab space station

On 8 August 1969, the McDonnell Douglas Corporation received a contract for the conversion of two existing S-IVB stages to the Orbital Workshop configuration. One of the S-IV test stages was shipped to McDonnell Douglas for the construction of a mock-up in January 1970. The Orbital Workshop was renamed "Skylab" in February 1970 as a result of a NASA contest.^[2]:115 The actual stage that flew was the upper stage of the AS-212 rocket (the S-IVB stage - S-IVB 212). The mission computer used aboard Skylab was the IBM System/4Pi TC-1, a relative of the AP-101 Space Shuttle computers.

Skylab was launched 14 May 1973 by a Saturn V (the last launch of such a rocket) with the upper stage removed, but with the avionics remaining in the same position (different from the Saturn INT-21 rocket, which could launch payloads not based on the S-IVB) into a 235-nautical-mile (435-km) orbit. The launch is sometimes referred to as Skylab 1, or SL-1. Severe damage was sustained during launch and deployment, including the loss of the station's micrometeoroid shield/sun shade and one of its main solar panels. Debris from the lost micrometeoroid shield further complicated matters by pinning the remaining solar panel to the side of the station, preventing its deployment and thus leaving the station with a huge power deficit.^[2]:253-255

Manned missions[link]

Skylab in orbit in 1973 as flown, docking ports in view

Three manned missions were made to Skylab: SL-2, SL-3 and SL-4 (see also the Mission designations section below).

The station underwent extensive repair during a spacewalk (extra-vehicular activity, or EVA) by the crew of the SL-2 mission, which launched on 25 May 1973 atop a Saturn IB. If the crew had failed to repair Skylab in time, the plastic insulation inside the station would have melted, releasing poisonous gas and making Skylab completely uninhabitable. They stayed in orbit with Skylab for 28 days. Two additional missions followed, with the launch dates of 28 July 1973 (SL-3) and 16 November 1973 (SL-4), and mission durations of 59 and 84 days, respectively. The last Skylab crew returned to the Earth on 8 February 1974.

Orbital operations[link]

Skylab orbited Earth 2,476 times during the 171 days and 13 hours of its occupation during the three manned Skylab missions. Astronauts performed ten spacewalks, totaling 42 hours and 16 minutes. Skylab logged about 2,000 hours of scientific and medical experiments, 127,000 frames of film of the Sun and 46,000 of the Earth.^[2]:340 Solar experiments included photographs of eight solar flares, and produced valuable results^[7]:155 that scientists stated would have been impossible to obtain with unmanned spacecraft.^[2]:342-344 The existence of the Sun's coronal holes were confirmed because of these efforts.^[2]:357 Many of the experiments conducted investigated the astronauts' adaptation to extended periods of microgravity.

Owen Garriott performing an EVA in 1973

A typical day began at 6 AM Central Time Zone.^[2]:307-308 Although the toilet was small and noisy, both veteran astronauts—who had endured earlier missions' rudimentary waste-collection systems—and rookies complimented it.^{[2]:165,307[7]:80[8]} The first crew enjoyed taking a shower once a week, but found drying themselves in weightlessness^[8] and vacuuming excess water difficult; later crews usually cleaned themselves daily with wet washcloths instead of using the shower. Astronauts also found that bending over in weightlessness to put on socks or tie shoelaces strained their stomach muscles.^[2]:306-308

Breakfast began at 7 AM. Astronauts usually stood to eat, as sitting in microgravity also strained their stomach muscles. They reported that their food—although greatly improved from Apollo—was bland and repetitive, and weightlessness caused utensils, food containers, and bits of food to float away; also, gas in their drinking water contributed to flatulence. After breakfast and preparation for lunch, experiments, tests and repairs of spacecraft systems and, if possible, 90 minutes of physical exercise followed; the station had a bicycle and other equipment, and astronauts could jog around the water tank. After dinner, which was scheduled for 6 PM, crews performed household chores and prepared for the next day's experiments. Following lengthy daily instructions (some of which were up to 15 meters long) sent via teleprinter, the crews were often busy enough to postpone sleep.^{[2]:309,334[9]:2-7}

Each Skylab mission set a record for the amount of time astronauts spent in space. The station offered what a later study called "a highly satisfactory living and working environment for crews", with enough room for personal privacy.^[9]:2-4 Although it had a dart set,^[10] playing cards, and other recreational equipment in addition to books and music players, the window with its view of Earth became the most popular way to relax in orbit.^{[7]:79-80,134-135}

Post SL-4 plans[link]

Skylab in February 1974, as SL-4 departs

Skylab was abandoned after the end of the SL-4 mission in February 1974, but to welcome visitors the crew left a bag filled with supplies and left the hatch unlocked.^[11] NASA discouraged any discussion of additional visits due to the station's age,^[2]:335,361 but in 1977 and 1978, when the agency still believed the Space Shuttle would be ready by 1979, it completed two studies on reusing the station.^[9]:3-1[11] By September 1978, the agency believed Skylab was safe for crews, with all major systems intact and operational.^[9]:3-2 It still had 180 man-days of water and 420 man-days of oxygen, and astronauts could refill both;^[11] the station could hold up to about 600 to 700 man-days of drinkable water and 420 man-days of food.^[9]:2-7

The studies cited several benefits from reusing Skylab, which one called a resource worth "hundreds of millions of dollars"^[9]:1-13 with "unique habitability provisions for long duration space flight."^[9]:3-11 Since no more operational Saturn V rockets were available after the Apollo program, four to five shuttle flights and extensive space architecture would have been needed to build another station as large as Skylab's 12,400 cubic feet (350 m³) volume.^{[9]:1-12 to 1-13} Its ample size—much greater than that of the shuttle alone, or even the shuttle plus Spacelab^[9]:2-8—was enough, with some modifications, for up to seven astronauts^[9]:2-31 of both sexes,^[9]:3-14 and experiments needing a long duration in space;^[9]:1-13 even a movie projector for recreation was possible.^[9]:3-11

Proponents of Skylab's reuse also said repairing and upgrading Skylab would provide information on the results of long-duration exposure to space for future stations.^[11] The most serious issue for reactivation was stationkeeping, as one of the station's gyroscopes had failed^[2]:361 and the attitude control system needed refueling; these issues would need EVA to fix or replace. The station had not been designed for extensive resupply. However, while plans had originally called for Skylab crews to perform only limited maintenance^[7]:34 they successfully made major repairs during EVA, such as the SL-2 crew's deploying of the solar panel^[7]:73-75 and the SL-4 crew's repair of the primary coolant loop.^{[2]:317[7]:130[9]:3-21} The SL-2 crew fixed one item during EVA by, reportedly, "hit[ting] it with [a] hammer."^[7]:89

Some studies also said, beyond the opportunity for space construction and maintenance experience, reactivating the station would free up shuttle flights for other uses,^[9]:1-13 and reduce the need to modify the shuttle for long-duration missions.^{[9]:2-9 to 2-10} Even if the station were not manned again, went one argument, it would serve as a useful experimental platform.^[9]:2-61

Shuttle mission plans[link]

The reactivation would likely have occurred in four phases:^[11]

Concept for proposed Skylab re-boost

1. An early Space Shuttle flight would have boosted Skylab to a higher orbit, adding five years of operational life. The shuttle might have pushed or towed the station, but attaching a booster—the Teleoperator Retrieval System (TRS)—to the station would have been more likely, based on astronauts' training for the task. Martin Marietta won the contract for the $26 million^[12] TRS, which contained about three tons of propellant.^[13] The remote-controlled booster had TV cameras and was designed for duties such as space construction and servicing and retrieving satellites the shuttle could not reach. After rescuing Skylab (or, if NASA chose, aiming it into the ocean) the TRS would have remained in orbit for future use.^[14]
2. In two shuttle flights, Skylab would have been refurbished. In January 1982, the first mission would have attached a docking adapter and conducted repairs. In August 1983, a second crew would have replaced several system components.
3. In March 1984, shuttle crews would have attached a solar-powered Power Expansion Package, refurbished scientific equipment, and conducted 30- to 90-day missions using the Apollo Telescope Mount and the earth resources experiments.
4. Over five years, Skylab would have been expanded to accommodate six to eight astronauts, with a new large docking/interface module, additional logistics modules, Spacelab modules and pallets, and an orbital vehicle space dock using the shuttle's external tank.

The first three phases would have required about $60 million in 1980s dollars, not including launch costs.

After departure[link]

After a boost of 6.8 miles (10.9 km) by SL-4's Apollo CSM before its departure, Skylab was left in a parking orbit of 269 miles (433 km) by 283 miles (455 km)^[2]:361 that was expected to last until at least the early 1980s, based on estimates of the 11-year sunspot cycle that began in 1976.^[2]:361[15] At the end of SL-4, only one Saturn IB rocket remained in the inventory—it was later used for Apollo-Soyuz Test Project—while all other Saturn IB and Saturn V rocket parts had been donated to museums. NASA began considering the potential risks of a space station reentry as early as 1962, but decided to not incorporate a retrorocket system in Skylab due to cost and acceptable risk.^[2]:127-129

The spent 49-ton Saturn V S-II stage which had launched Skylab in 1973 remained in orbit for almost two years, and made an uncontrolled reentry on January 11, 1975. Some debris, most prominently the five heavy J-2 engines, likely survived to impact in the North Atlantic Ocean. Although this event did not receive heavy media or public attention, it was followed closely by NASA and the Air Force, and helped emphasize the need for improved planning and public awareness for Skylab's eventual reentry.^{[citation needed]}

Solar activity[link]

Greater-than-expected solar activity^[2]:362 heated the outer layers of the Earth's atmosphere and thereby increased drag on Skylab. By late 1977, NORAD accurately forecast a reentry in mid-1979;^[15] a National Oceanic and Atmospheric Administration (NOAA) scientist criticized NASA for using an inaccurate model for the second most-intense sunspot cycle in a century, and for ignoring NOAA predictions published in 1976.^[2]:362-363

The reentry of the USSR's nuclear powered Cosmos 954 in January 1978, and the resulting radioactive debris fall in northern Canada, drew more attention to Skylab's orbit. Although Skylab did not contain radioactive materials, the State Department warned NASA about the potential diplomatic repercussions of station debris.^[2]:363 Battelle Memorial Institute forecast that up to 25 tons of metal debris could land in 500 pieces over an area 4,000 miles long and 1,000 miles wide. The lead-lined film vault, for example, might land intact at 400 feet per second.^[16]:80 Ground controllers re-established contact with Skylab in March 1978^[15] and recharged its batteries.^[17] Although NASA worked on plans to reboost Skylab with the Space Shuttle through 1978 and the TRS was almost complete, the agency gave up in December when it became clear that the shuttle would not be ready in time;^{[2]:363-367[12]} its first flight, STS-1, did not occur until April 1981. Also rejected were proposals to launch the TRS using one or two unmanned rockets^[11] or to attempt to destroy the station with missiles.^[16]:80

Re-entry[link]

Skylab's demise was an international media event, with merchandising of t-shirts and hats with bullseyes,^[16]:80 wagering on the time and place of re-entry, and nightly news reports. The San Francisco Examiner offered a $10,000 prize for the first piece of Skylab delivered to its offices; the competing Chronicle offered $200,000 if a subscriber suffered personal or property damage.^[17] NASA calculated that the odds of station re-entry debris hitting a human were 1 to 152^[2]:369—although the odds of debris hitting a city of 100,000 or more were 1 to 7—and special teams were readied to head to any country hit by debris and requesting help.^[17]

In the hours before re-entry, ground controllers adjusted Skylab's orientation to try to minimize the risk of re-entry on a populated area.^[17] They aimed the station at a spot 810 miles (1,300 km) south southeast of Cape Town, South Africa, and re-entry began at approximately 16:37 UTC 11 July 1979.^[2]:371 The Air Force provided data from a secret tracking system able to monitor the reentry.^[18] The station did not burn up as fast as NASA expected, however. Due to a 4% calculation error, debris landed southeast of Perth, Western Australia,^[2]:371 and was found between Esperance and Rawlinna, from 31° to 34°S and 122° to 126°E. Residents and an airline pilot saw dozens of colorful fireworks-like flares as large pieces broke up in the atmosphere.^[16]:81 The Shire of Esperance facetiously fined NASA A$400 for littering, a fine which remained unpaid for 30 years.^[19] The fine was paid in April 2009, when radio show host Scott Barley of Highway Radio raised the funds from his morning show listeners and paid the fine on behalf of NASA.^[20]

Fragment of Skylab recovered after its re-entry through Earth's atmosphere, on display at the U.S. Space & Rocket Center.

Seventeen year-old Stan Thornton found 24 pieces of Skylab at his home in Esperance. A Philadelphia businessman flew him, his parents, and girlfriend to San Francisco, where he collected the Examiner prize.^{[2]:371[16]:81} In a coincidence for the organizers, the annual Miss Universe pageant was scheduled to be held a few days later, on 20 July 1979 in Perth. A large piece of Skylab debris was displayed on the stage.^[21] Analysis of the debris showed that the station had not disintegrated until 10 miles above the Earth, much lower than expected.^[16]:82

After the demise of Skylab, NASA did not launch another space station until it began construction of the International Space Station (ISS) in 1998, in partnership with Russia, the European Space Agency (ESA), Japan and Canada. A proposed all-American successor to Skylab, Space Station Freedom, was merged into the plans for the ISS in 1993.

Planned, but unflown missions[link]

Skylab 5[link]

Skylab 5 would have been a short 20-day mission to conduct scientific experiments and boost Skylab into a higher orbit. Vance Brand (commander), Don Lind (command module pilot), and William B. Lenoir (science pilot) would have been the crew for this mission, with Brand and Lind being the prime crew for the never-flown Skylab Rescue flights.^[22] Brand and Lind also trained for a mission that would have aimed Skylab for a controlled deorbit.^[18]

Skylab B[link]

A flight-quality backup Skylab was built. NASA considered using it for a second station in May 1973 or later, to be called Skylab B (S-IVB 515), but decided against it. Launching another Skylab with another Saturn V rocket would have been very costly, and it was decided to spend this money on the development of the Space Shuttle instead. The backup is on display at the National Air and Space Museum in Washington, D.C.

Engineering mock-ups[link]

A full-size training mock-up once used for astronaut training is located at the Lyndon B. Johnson Space Center visitor's center in Houston, Texas. Another full-size training mock-up has been decaying in a museum parking lot exposed to the elements in Huntsville, Alabama, after it was moved outdoors to make way for an exhibit on the Soviet and later Russian Mir space station. This Skylab engineering mock-up was being considered for restoration and display at the U.S. Space & Rocket Center.^[23]

Mission designations[link]

The numerical identification of the manned Skylab missions was the cause of some confusion. Originally, the unmanned launch of Skylab and the three manned missions to the station were numbered SL-1 through SL-4. During the preparations for the manned missions, some documentation was created with a different scheme -- SLM-1 through SLM-3 -- for those missions only. William Pogue credits Pete Conrad with asking the Skylab program director which scheme should be used for the mission patches, and the astronauts were told to use 1-2-3, not 2-3-4. By the time NASA administrators tried to reverse this decision, it was too late, as all the in-flight clothing had already been manufactured and shipped with the 1-2-3 mission patches.^[24]

Mission	Emblem	Commander	Pilot	Science Pilot	Launch date	Landing date	Duration (days)
Skylab 1 SL-1		unmanned launch of space station			1973-05-14 17:30:00 UTC	1979-07-11 16:37:00 UTC	2248.96
Skylab 2 SL-2 (SLM-1)		Pete Conrad	Paul Weitz	Joseph Kerwin	1973-05-25 13:00:00 UTC	1973-06-22 13:49:48 UTC	28.03
Skylab 3 SL-3 (SLM-2)		Alan Bean	Jack Lousma	Owen Garriott	1973-07-28 11:10:50 UTC	1973-09-25 22:19:51 UTC	59.46
Skylab 4 SL-4 (SLM-3)		Gerald Carr	William Pogue	Edward Gibson	1973-11-16 14:01:23 UTC	1974-02-08 15:16:53 UTC	84.04

Program cost[link]

The Skylab program cost $2.2 billion from 1966 to 1974, or $10 billion in 2010 inflation-adjusted dollars. As its three three-man crews spent 510 total man-days in space, each man-day cost $19.6 million in 2010 dollars, compared to $7.5 million for the International Space Station.^[25]

Gallery[link]

• 

  The waste management facilities in the backup Skylab at the National Air and Space Museum.

• 

  An astronaut mannequin dines aboard the backup Skylab at the Smithsonian NASM.

• 

  SkyLab commemorative stamp, Issue of 1974. The commemorative stamp reflects initial repairs to the station, including the parasol sunshade.

• 

  Illustration of Skylab configuration with docked Command/Service Module

• 

  Vanguard (T-AGM-19) seen as a NASA Skylab tracking ship. Note the tracking radar and telemetry antennas.

Cut-away view of Skylab as planned, docked with Apollo CSM.

See also[link]

Spaceflight portal

• Skylab Medical Experiment Altitude Test (SMEAT)
• Splashdown (spacecraft landing)
• Mir

References[link]

 This article incorporates public domain material from websites or documents of the National Aeronautics and Space Administration.

Further reading[link]

Robbins Medallions issued for Skylab Missions.

• SKYLAB: A CHRONOLOGY by Roland W. Newkirk and Ivan D. Ertel with Courtney G. Brooks (NASA SP-4011 1977)
• SP-402 A New Sun: The Solar Results from Skylab
• Skylab Mission Evaluation - NASA report (PDF format)
• Skylab Reactivation Mission Report 1980 - NASA report (PDF format)

External links[link]

Wikimedia Commons has media related to: Skylab

NASA[link]

• NASA History Series Publications (many of which are on-line)
  • EP-107 Skylab, a guidebook (1973) 1
  • SP-4011 Skylab, a Chronology (1977) 1
  • SP-4208 Living and Working in Space: A History of Skylab (1983)
  • SP-400 Skylab, Our First Space Station (1977)
  • SP-401 Skylab, Classroom in Space (1977)
  • SP-399 Skylab EREP Investigations Summary (1978)
  • SP-402 A New Sun: Solar Results from Skylab (1979)
  • SP-404 Skylab's Skylab's Astronomy and Space Sciences (1979)
• Airlock Module under construction (1971) (Medium)
• Airlock and Docking Module together (1972) (Medium)
• Skylab Crew Quarters Illustration
• Apollo (in foreground) and Skylab space food (M487)

3rd Party[link]

• eoPortal: Skylab
• Historic Spacecraft: Skylab
• Skylab reboost module
• Skylab Reentry (Chapter 9 of SP-4208)
• Skylab cutaway drawing from Encyclopædia Britannica
• Cutaway line drawing of Skylab
• Skylab "Christmas tree"

v t e Project Skylab missions Flown Skylab 1 · Skylab 2 · Skylab 3 · Skylab 4 Canceled Skylab 5 Unflown Skylab Rescue · Skylab B

v t e United States human spaceflight programs Active ISS (joint) Previous X-15 (suborbital) Mercury Gemini Apollo Skylab Apollo-Soyuz (with USSR) Space Shuttle Shuttle-Mir (with Russia) Canceled MISS Orion (nuclear) Dyna-Soar Manned Orbiting Laboratory National Aero-Space Plane Space Station Freedom (now ISS) Orbital Space Plane Project Constellation

v t e Missions of the Apollo program Rocket tests SA-1 SA-2 SA-3 SA-4 SA-5 AS-203 Abort tests QTV Pad Abort Test-1 A-001 A-002 A-003 Pad Abort Test-2 A-004 Boilerplate tests A-101 A-102 A-103 A-104 A-105 Unmanned missions AS-201 AS-202 Apollo 4 Apollo 5 Apollo 6 Skylab 1 Low Earth orbit missions Apollo 7 Apollo 9 Skylab 2 Skylab 3 Skylab 4 Apollo-Soyuz Test Project Lunar orbit missions Apollo 8 Apollo 10 Lunar landing missions Apollo 11 Apollo 12 Apollo 14 Apollo 15 Apollo 16 Apollo 17 Failed missions Apollo 1 (AS-204) Apollo 13 List of missions Mission types Canceled missions

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Danilo Gentili
Born	(1979-09-27) September 27, 1979 (age 32) Santo André, SP, Brazil
Occupation	Advertiser, comedian, writer, cartoonist, reporter, TV show host and businessman.
Website
http://www.danilogentili.com/

Danilo Gentili Junior, better known as Danilo Gentili (Santo André, September 27, 1979) is an advertiser, comedian, writer, cartoonist, reporter, businessman and talk-show host. Has emerged in Brazil as part of the comedy TV show CQC Brasil, Rede Bandeirantes and recently has got his own talk-show, Agora é Tarde.^[1]

Biography[link]

Danilo Gentili graduated in 2003 in Social Communication - Advertising UniABC.^[2] In 2006 he founded a comedy show called Comedia ao Vivo,.^[3] That same year, he joined the Stand-Up Comedy group Clube da Comédia. Danilo is a cartoonist and caricaturist. Wrote a column on Mondays for one of the newspapers with more printed issues in Brazil, Metro. In 2008 he was awarded 'Paulistano of the Year' by Veja megazine and collaborated with the largest circulation magazine in Brazil, Mad. In 2010, alongside his comedy partner Rafinha Bastos and producer Ítalo Gusso, opened at Rua Augusta in São Paulo, the first American style comedy club in Brazil, called Comedians Comedy Club.^[4]

CQC[link]

After a few appearances on TV, he was invited to participate in comedy TV show called Custe o que Custar (CQC), on TV Bandeirantes. On his “audition”, which was actually his first interview, he left the singer Agnaldo Timóteo on an awkward situation with all his nonsense questions. That interview paid off. It was a big success. What was supposed to be a temporary job, turned out to be his great starting point on TV.

The show became famous due to “Inexperienced Reporter” (Reporter Inexperiente), a part of the show where Danilo pretended to be a newbie interviewing guests and asking them all kinds of nonsense questions. After a while he started doing more than that on the show. So he stood out on CQC interviewing people all over, especially about politics. At the Congress he became that reporter that every politician was afraid of. They tried to avoid being ridiculed when faced with his questions and being confronted with truths (which the viewers themselves would like to do so).

During the CQC Season of 2010/2011, Danilo Gentili was conducting segments on the show called “Protest Now” and "National Identity".

On the last episode of the 2011 season, Danilo said his goodbye to the show so he could dedicate 100% of himself to his new project, the talk show "Agora é Tarde". At the occasion, he was honored by the show, which he was a part of for 4 seasons.

Agora é Tarde[link]

Host and co-creator of the late-night show Agora é Tarde (It's too late)^[5].. This late-night talk show premiered June 2011 on TV Band and got high ratings and great reviews. The show has Ultraje a Rigor as the supporting band, has comedy segments, stand-up monologue, round-table with comedians talking about recent news and Brazilian stars as the main guests. His main opponent, not directly in the format Jô Soares is a "dinosaur of the tv" as he says in his acid comments during their show. The dispute of late nights in Brazil begins to reassemble the remote battle between David Letterman and Jay Leno on American TV, Danilo and Jô often indirect attack each other in shows where they are asked and that they have improved the quality of shows and interest in being interviewed Brazilian celebrities. Danilo often says that Jô did not invent the format and that his opponent got settled for decades because he didn't have any competition. The media still doubter the politically incorrect boy of possibly becoming one of the biggest interviewers in Latin America. The show have been considered the Brazilian version of 'The Daily Show', with Jon Stewart.

Awards[link]

O Globo[link]

'Agora é Tarde' was chosen by this important newspaper publication as "Best 2011 TV Show" and Danilo Gentili, the 'Best TV Show Host'.

Troféu Imprensa[link]

'Agora é Tarde' was chosen by the Brazilian Press Association as the 'Best Talk Show' in the 2012 edition of the awards.

Critics' Recognition[link]

Other than the awards, the show has been highly acclaimed by the critcs for the quality of the show and also for the host's skills. According to the columnist Flávio Ricco, from UOL, "Danilo showed, more than anything, to be a real hard worker. A lot of what you see on the show is due to his strength and perseverance.'

Comedy Central Apresenta[link]

“Comedy Central Apresenta” (Comedy Central Presents) is the first show from Comedy Central produced in Brazil. Danilo Gentili was chosen by the channel as the host of this project, that mainly consists on a typical stand-up night club show.

Businessman[link]

In 2010, alongside his comedy partner Rafinha Bastos and producer Ítalo Gusso, opened at Rua Augusta in São Paulo, the first American style comedy club in Brazil, called Comedians Comedy Club,^[6] which opens Tuesdays through Sundays.

International Critics[link]

The New York Times[link]

In 2011 Danilo Gentili was mentioned in The New York Times for his comedian work in Brazil. About him, The New York Times wrote:

"Supplying Brazil’s Laugh Track" - With his baby face, boyish manner and goofy laugh, Mr. Gentili, 32, is the enfant terrible of comedy in Brazil. He has built his reputation on a willingness to ask celebrities — and especially politicians — questions that are considered embarrassing, outrageous or disrespectful. Recently he also got himself into trouble with a Twitter post that enraged Jewish community leaders in São Paulo. Even so, in June he became host of a late-night talk show on a national network and the big question now is: Will that format succeed in taming him? So far, the answer is no.^[7]

"A Brazilian’s Comic Mania: Social Media" - Danilo Gentili, partner of a comedy club, has more than a touch of Bill Maher in him, as shown by a DVD called “Politicamente Incorreto.” “We’re not considered artists, we’re compared to punk rockers playing in the garage to see what happens, and I’m fine with that,” said Mr. Gentili, 32, who has just been given a late-night talk show on the Bandeirantes network.^[8]

The Guardian[link]

"Brazil's stand-up comics lead social revolution against powerful elites" - Danilo Gentili comedy also drew attention of England’s leading newspaper, The Guardian. In Tom Phillips's article, Gentili is named a comedian that leads a revolution “a highly controversial but also wildly popular comedian who is blazing a trail for stand-up comedy in South America's largest nation, is a man who enjoys living on the edge.”

The newspaper has highlighted the following of Mr. Gentili: "We earn money this way. If people get on TV they'll earn more money, even better. But if they don't, damn it. This will keep happening. So they don't owe allegiance to anyone.",

"Anywhere in the world people understand that the role of the comedian is to crack jokes. One day they'll understand it in Brazil, too, I hope," he said.^[9]

Manager Magazin[link]

Danilo Gentili was once again mentioned in an international article. After the British 'The Guardian' ^[9] and American 'The New York Times',^[8] now it's German Manager Magazin - a business magazine from the Der Spiegel group, one of the most important ones in Germany - who mentions the Brazilian comedian.

In the article, that brings to attention the advances of Brazilian technology, Gentili is presented as an influential comedian online, with more than 2 million twitter followers. http://www.manager-magazin.de/unternehmen/it/0,2828,795446,00.html

Prospect Magazine[link]

Danilo Gentili made the headline of another British article, this time the 'Prospect Magazine' compares the Brazilian comedian with Jon Stewart and stats that Gentili is helping Brazil match economic weight with cultural clout.^[10]

Forbes Magazine[link]

The worldwide famous Forbes magazine add Danilo Gentili on their list of "Names you Need to Know". With a brief history on the comedians and a Q&A, the magazine highlights Danilo as the country’s latest comic phenomenon. ^[11]

Stand-up Comedy[link]

Politically Incorrect[link]

In October 2010, Danilo had his first stand-up solo about politics broadcast LIVE. Over a million people watched the show online. The show became a DVD, an audiobook on CD available for download and the book "Politically Incorrect."

Danilo Gentili: Volume 1[link]

Considered a great surprise for the Brazilian comedy, Danilo sees the world in a very peculiar way. With a humorous and critical view of events, he builds his shows from the common life: personal frustrations, relationships, politics, current events, unusual facts and even the most trivial things, everything becomes raw material for his funny and clever work. Danilo Gentili naturally seem to know the recipe of the genre: originality, surprise, charisma and connection with the audience, these are the perfect ingredients for a good dose of humor, the one of the best medicine there is. After years of performing in bars and theaters, Danilo selected the tested and approved material by his audience and put together a 1-hour solo show and recently has documented that show so it will come out as a DVD later 2011.

Work[link]

Television[link]

In São Paulo Gay Pride Parade, 2009.

Theater[link]

• 2005/2009 - Clube da Comédia Stand-Up - author and comedian
• 2006/2009 - Comédia Ao Vivo - creator, comedian and author
• 2009 - Divina Comédia - creator, comedian and author (alongside other comedians)
• 2007/2008 - Circuito Baviera Premium - comedian and author
• 2008/2011 - Danilo Gentili Volume 1 (Stand-Up Comedy Solo Show) - comedian and author
• 2010 - Politicamente Incorreto (Stand-Up Comedy Solo Show) - comedian and author
• 2011 - Virada Cultural de São Paulo

Cartoonist[link]

• 2009 - Mad Magazine - Writer and cartoonist

Businessman[link]

• 2010 - Comedians Comedy Club^[13] - Partner

Products[link]

DVD[link]

• 2010 - Politicamente Incorreto
• 2011 - Danilo Gentili - Volume 1

Books[link]

• 2009 - Como se Tornar o Pior Aluno da Escola (How to Become School's Worst Student) - Panda Books Publishing Company - author and illustrator
• 2010 - Politicamente Incorreto (Politically Incorrect) - Panda Books Publishing Company - author and illustrator

Games[link]

• 2011 - O Mundo vs Danilo Gentili (The World versus Danilo Gentili) –^[14]

References[link]