Pioneer 11: First Spacecraft to Saturn

Forty years ago today — April 5, 1973 — an Atlas Centaur rocket launched from Cape Canaveral carrying the Pioneer 11 space probe.

(Pioneer 11. NASA image.)

Pioneer 11 launched at 02:11 April 6th UTC, though it was still April 5th in Florida when it lifted off. It followed its sister ship, Pioneer 10, which had launched a little over a year before (on March 2, 1972).

Pioneer 11 was the first spacecraft to travel to Saturn, and returned close-up pictures of the ringed planet. On its way to Saturn, it used Jupiter’s gravity for course correction, and in so doing became the first spacecraft to photograph Jupiter’s polar region.

Pioneer 11 passed by Saturn on September 1, 1979, and then continued on toward the edge of the Solar System and the constellation Sagittarius. Contact with the spacecraft was lost in late 1995.

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Fifteen Years Apart: Apollo 6 and STS-6

Forty-five years ago today — April 4, 1968 — the final qualification flight of the Saturn V launch vehicle and the Apollo spacecraft launched from the Kennedy Space Center.

(Apollo 6 launch. NASA image.)

Apollo 6 consisted of a complete three-stage Saturn V, a Command and Service Module, and a “boilerplate” or “pathfinder” Lunar Module. The mission encountered several major problems:

Two minutes and five seconds after launch, the Saturn V structure underwent a severe pogo oscillation, without damage to the spacecraft structure. Due to a manufacturing flaw and unrelated to the pogo oscillations, structural panels were lost from the lunar module adapter. Finally, after the completion of first stage firing and part way through the second stage burn, two of the five second stage J-2 engines shut down prematurely. The planned 175 km circular Earth orbit was not achieved, instead, after completion of the third stage burn, the spacecraft was in a 172.1 x 223.1 km, 89.8 min orbit. After two orbits, the third stage failed to reignite as planned, so the Service Module propulsion system was used to boost the spacecraft to an apogee of 22,225.4 km, from which the planned lunar reentry simulation took place at 36,025 km/hr, slightly less than the planned velocity of 40,000 km/hr. The Command Module splashed down 80 km off target 9 hr 50 min after launch and was recovered in good condition.

Fifteen years later, on April 4, 1983, the Space Shuttle Challenger launched from the Kennedy Space Center on its first flight, mission STS-6. Astronauts Paul J. Weitz, Karol J. Bobko, Donald H. Peterson and Story F. Musgrave spent 5 days in space and deployed the first Tracking and Data Relay Satellite.

The STS-6 mission was not without its problems. The Inertial Upper Stage placed TDRS-1 in the wrong orbit, and later the satellite’s own thrusters were used to put it into the correct orbit (much like the service module’s thrusters being used on Apollo 6, and some recent spacecraft which have been recovered by judicious use of on-board propulsion). Nevertheless, the overall STS-6 mission was successful and featured the first spacewalk from a Shuttle.

Looking back at these two launches, it seems our space exploits have regressed instead of progressed. Given 10 years between Explorer 1 and Apollo 6, and 15 years between Apollo 6 and STS-6, and 30 years since then, you might think that we should have a colony on Mars by now. So this image of Challenger rolling out in the fog seems apt:

(STS-6 rollout to pad 39A, in the fog. NASA image.)

Here’s hoping we soon catch up to the future!

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The Mystery of Salyut 2

Forty years ago today — April 3, 1973 — the USSR launched Salyut 2 from the Baikonur Cosmodrome on a Proton K rocket.

(Line drawing of an Almaz space station. NASA image from Wikimedia Commons.)

According to the National Space Science Data Center, Salyut 2 “was designed for scientific research and testing of onboard systems and units” and failed “11 days after launch [due to] an unexplainable accident.”

The Wikipedia entry tells a different story: that Salyut 2 was one of the Soviet Union’s Almaz modules — a space station designed for military use, in answer to the USAF’s proposed Manned Orbiting Laboratory — and the first of the Almaz units to reach orbit. The station’s true purpose was hidden in plain sight by its being designated as a Salyut module.

Wikipedia also includes an explanation for the Almaz/Salyut’s failure:

Three days after the launch of Salyut 2, the Proton’s spent third stage exploded. Thirteen days into its mission, Salyut 2 began to depressurise, and its attitude control system malfunctioned. An inquiry into the failure initially determined that a fuel line had burst, burning a hole in the station. It was later discovered that a piece of debris from the third stage had collided with the station, causing the damage.

The source for the additional Salyut 2 information is this Russian Space Web page, which also notes that

Soon after the accident, official Soviet sources announced that the Salyut-2 had completed its operations “after a series of tests.” For years, official Soviet sources continued to claim that “during entire flight (of Salyut-2) reliable radio-contact with the station had been maintained … and all onboard systems and science equipment of the station had functioned normally.”

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Exploring Earth’s Atmosphere, a Lunar Flyby, and a Space Odyssey

Fifty years ago today — April 2, 1963 — two quite different launches happened in the U.S. and the Soviet Union.

(Explorer 17. NASA image.)

The U.S. launched Explorer 17, also known as Atmospheric Explorer A, the first in a series of satellites to study the upper atmosphere. The satellite launched in the late evening — already April 3rd, UTC — on a Thor-Delta rocket out of Cape Canaveral, and operated until its batteries failed in July 1963.

Earlier in the day, the Soviet Union had launched Luna 4, the “first successful spacecraft of their ‘second generation’ lunar program.” It launched from the Baikonur Cosmodrome on a Molniya rocket — a Modified SS-6 (Sapwood) ICBM. Interestingly, the USSR did not reveal Luna 4’s intended mission, but “was announced it would travel to ‘the vicinity of the Moon.'”

Rather than being sent on a straight trajectory toward the Moon, the spacecraft was placed first in a 167 x 182 km Earth orbit and then was rocketed in a curving path towards the Moon. Luna 4 achieved the desired initial trajectory but during trans-lunar coast the Yupiter astronavigation system failed (most likely due to thermal control problems) and the spacecraft could not be oriented properly for the planned midcourse correction burn. Communications were maintained, but Luna 4 missed the Moon by about 8400 km (sources give reports of 8336.2, 8451, and 8500 km) at 13:25 UT on 5 April 1963 and entered a 89 250 x 694 000 km equatorial Earth orbit. The spacecraft transmitted at 183.6 MHz at least until 7 April. The orbit is believed to have been later perturbed into a heliocentric orbit.

… It was speculated the probe was designed to perform a soft landing on the Moon based on the trajectory and on the later attempted landings of the Luna 5 and 6 spacecraft, as well as the advances made over the 3 years since the successful Luna 3 flyby. (And the fact that a lecture program entitled “Hitting the Moon”, scheduled to be broadcast on Radio Moscow at 7:45 p.m. the evening of April 5, was cancelled.)

Before all of this happened, on this date 55 years ago President Dwight D. Eisenhower sent “draft legislation to Congress establishing the ‘National Aeronautics and Space Agency.'” The name was soon changed to the National Aeronautics and Space Administration. You can read more about NASA’s beginnings here.

Finally, 45 years ago today — April 2, 1968 — 2001: A Space Odyssey premiered at the Uptown Theatre in Washington, DC. This page includes a retrospective on its early run.

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Pegasus Carries Solar Explorer

Fifteen years ago today — April 1, 1998* — a Pegasus XL originating from Vandenberg AFB carried a small satellite to study the Sun’s atmosphere.

(Coronal “loops” above the Sun’s surface, in a false-color image from TRACE. NASA image.)

The Transition Region And Coronal Explorer, or TRACE, carried a single multi-spectral instrument to

examine the three-dimensional magnetic structures which emerge through the Sun’s photosphere (the visible surface of the Sun) and define both the geometry and dynamics of the upper solar atmosphere (the transition region and corona).

In more detail, TRACE was built to achieve three primary objectives:

  1. follow the evolution of magnetic field structures from the solar interior to the corona;
  2. investigate the mechanisms of the heating of the outer solar atmosphere; and,
  3. determine the triggers and onset of solar flares and mass ejections.

The effectiveness of TRACE’s telescopic sensor was due to its sophisticated attitude control system, which combined magnetic-torquers, reaction wheels, and inertial gyros to maintain its pointing accuracy within 5 arc-seconds.

The TRACE mission lasted until June 2010, and produced some stunning images of our Sun.


*April 2nd UTC.

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Last Saturn-Apollo Block 1 Suborbital Test Flight

Fifty years ago today — March 28, 1963 — the Saturn-Apollo 4 mission was launched from Cape Canaveral.

(Saturn SA-4. NASA image.)

Saturn-Apollo (SA) 4, or Apollo SA-4, was the final “Block 1” Saturn test, the last of four test launches of the Saturn rocket’s first stage.

The rocket was launched on a sub-orbital flight to an altitude of 129 km and a peak velocity of 5906 km/hr. After 100 seconds of flight, a pre-set timer cut off engine no. 5 as planned to test the “engine-out” capability of the booster. Fuel was successfully routed to the other seven engines and the flight continued.

Also on this date in space history, 30 years ago, the first of an advanced series of remote-sensing spacecraft, NOAA 8, launched into a polar orbit atop an Atlas E rocket out of Vandenberg AFB. Unfortunately, the satellite did not live out its two-year planned operational life: it failed in June 1984.

Finally, 10 years ago today — March 28, 2003 — Japan launched a pair of reconnaissance satellites, IGS (Information Gathering Satellite) 1A and IGS 1B, from Tanegashima Space Center on an H-2A rocket. According to the National Space Science Data Center, “One of the two spacecraft uses optical cameras with a resolution of one meter; the other uses synthetic aperture radar to provide images at a resolution of a few meters,” but it is unclear which satellite carried which sensor.

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Last Launch from San Marco, Kenya

Twenty-five years ago today — March 25, 1988 — a joint U.S.-Italy mission lifted off from the San Marco Range, Kenya, on a Scout launch vehicle.

(Scout X-4 rocket with the earlier US-Italian satellite San Marco 1. NASA image from Wikimedia Commons.)

The last satellite orbited from the San Marco facility on the Kenyan coast, San Marco D/L carried a specialized suite of sensors to study the interaction between the solar wind and the Earth’s thermosphere and ionosphere. One instrument, the Wind and Temperature Spectrometer, failed after 20 days, but the rest of the spacecraft operated nominally. Though the satellite was intended to last a full year, it re-entered the atmosphere on December 6, 1988.

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Space History: the Nascent Strategic Defense Initiative

Thirty years ago today — March 23, 1983 — President Ronald Reagan announced a research program that would eventually become the Strategic Defense Initiative (SDI).

President Reagan called for a major research-and-development effort on space-based defenses against ballistic missile attacks. Some of the work I did in the Air Force was related to SDI, which became known (usually pejoratively) as “Star Wars.”

Those of us who were geeks of one stripe or another didn’t really mind the nickname.

According to this excerpt from Way Out There in the Blue: Reagan, Star Wars and the End of the Cold War by Frances Fitzgerald,

The announcement, made in an insert into a routine defense speech, came as a surprise to everyone in Washington except for a handful of White House aides. The insert had not been cleared with the Pentagon, and although Reagan was proposing to overturn the doctrine which had ruled U.S. nuclear strategy for more than three decades, the secretary of defense and the secretary of state were informed only a day or so before the speech was broadcast.

I find that fascinating: visionary, and quite bold. I appreciate that.

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Space History, 1958: Vanguard 1

Fifty-five years ago today — March 17, 1958 — a Vanguard rocket carried the Vanguard 1 satellite to orbit out of Cape Canaveral.

(Vanguard 1. Note the very small solar panels on the side of the satellite. NASA image.)

Vanguard 1 was placed in an elliptical orbit with a perigee of 654 km (406 mi) and an apogee of 3969 km (2466 mi), inclined 34.25 degrees from the equator.

Original estimates had the orbit lasting for 2000 years, but it was discovered that solar radiation pressure and atmospheric drag during high levels of solar activity produced significant perturbations in the perigee height of the satellite, which caused a significant decrease in its expected lifetime to only about 240 years.

Vanguard 1’s batteries ran down in June 1958, stopping its battery-powered 10-mW transmitter, but its solar-powered 5-mW transmitter continued operating until May 1964. Vanguard 1 may still be optically tracked from Earth, and is the longest-orbiting man-made satellite.

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X-38 ‘Crew Return Vehicle’ Test Flight

Fifteen years ago yesterday — March 12, 1998 — NASA conducted the first “drop test” of the X-38 at the Dryden Flight Research Center at Edwards AFB.

(The X-38 drops away from NASA’s B-52. NASA image from Wikimedia Commons.)

The X-38 program developed a series of prototype “lifeboats” for the International Space Station. The Crew Return Vehicle (CRV) would have been

an emergency vehicle to return up to seven International Space Station (ISS) crewmembers to Earth. It [would] be carried to the space station in the cargo bay of a space shuttle and attached to a docking port. If an emergency arose that forced the ISS crew to leave the space station, the CRV would be undocked and – after a deorbit engine burn – the vehicle would return to Earth much like a space shuttle.

The X-38 program was cancelled in 2002.

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