Editing Ranger 5 (section)

== Mission ==
[[File:Ranger 5 Launch.jpg|thumb|right|Ranger 5 lifted off from launch Complex 12]]
Ranger 5 was scheduled for launch in June 1962, but [[NASA]] instead decided to fly the Mariner Venus probes (derived from Block I Ranger) first which gave more time to work out problems with the spacecraft. After [[Mariner 1]] ended its mission in the Atlantic Ocean instead of interplanetary space, the agency started coming under increased scrutiny from [[U.S. Congress|Congress]] due to its apparent inability to have any kind of success with planetary probes. [[Grand Old Party|Republican]] Congressman [[James G. Fulton|James Fulton]] confronted [[NASA]] Director of the Office of Programs J.J. Wyatt, noting that Mariner 1 had cost U.S. taxpayers $14 million and that there was no excuse at this point for failures every launch. As July 1962 ended, there had been 12 planetary probe attempts going back to 1958 and only two ([[Pioneer 4]] and [[Pioneer 5]]) accomplished all of their mission goals. It might have been small consolation that [[Soviet]] planetary probe efforts during this time were little more successful, but all of their failures were kept secret, so the Soviets did not have to answer to their public about the waste of tax money on failed space missions.

The successful launch of [[Mariner 2]] on August 27 momentarily blunted criticism of [[NASA]] and [[Jet Propulsion Laboratory]] and also seemed to verify the soundness of the [[Ranger program|Ranger]] design. Meanwhile, JPL engineers were still trying to figure out what had caused the computer failure on [[Ranger 4]], which had occurred during a period when the probe was out of range of ground tracking. The malfunction was especially puzzling because the probe had been given very thorough ground testing without any anomalies occurring. Examination of [[telemetry]] records seemed to suggest that the failure had occurred during separation of [[Ranger 4]] from the Agena, at the point where the electrical interface between the two was disconnected and Ranger 4 would have switched to internal power. The behavior of the probe indicated a transformer or inverter malfunction, probably a [[short circuit]] caused by loose metal coatings contacting the pins on the power umbilical attaching the probe to the Agena. Modifications to Ranger 5 included a backup timer to ensure continued operation of the telemetry system if the main computer failed, an additional nitrogen bottle to the attitude control system to reduce gas pressure, and an additional pyrotechnic igniter for the midcourse correction engine. Most importantly, extra diodes and fuses were added to the [[Electrical conductor|electrical]] lines to prevent another short from occurring.

[[File:Ranger block2.jpg|thumb|left|165px|Ranger 5]]
[[File:Ranger 5 Postlaunch Press Conference.jpg|thumb|Ranger Program officials Assembled for the Ranger 5 Postlaunch Press Conference at Cape Canaveral. Left to Right: Friedrich Duerr, Major J. Mulladay, Lt. Col. Jack Albert, [[Kurt H. Debus|Kurt Debus]], William Cunningham, and [[James Burke (space engineer)|James Burke]]]]
Ranger 5 was heat-sterilized like Rangers 3-4 had been, so as to prevent unintended contamination of the Moon with Earth microbes. Rolf Halstrup, who was in charge of the sterilization program, had vocally objected to this procedure as he was convinced that subjecting the probes to a heat dosage was damaging the sensitive electronics in them. He convinced [[JPL]] in [[Pasadena, California|Pasadena]] management that sterilization of Ranger 4 had "very likely" damaged the main computer sequencer and timer and that the procedure needed to be stopped to ensure reliability of the spacecraft. Management agreed to stop sterilizing Ranger probes, but only on [[Ranger 8]] and up, as [[Ranger 6|Rangers 6]]-[[Ranger 7|7]] had already been sterilized.

On August 20, Ranger 5 began the long cross-country trip from state of California to Florida and arrived there the day of [[Mariner 2]]'s launch. Atlas 215D and Agena 6005 arrived later that week and prelaunch checkouts were started. Initial preparations focused on the launch vehicle itself, which was causing almost as many problems as the Ranger probes themselves. The Atlas-Agena combination malfunctioned four out of the six times that [[NASA]] had launched it and every booster that was delivered to [[Cape Canaveral]] required modifications or repair work before it could fly. Moreover, in the year between [[Ranger 1]] and [[Mariner 2]], there had been no improvement whatsoever in the quality control of the Atlas-Agenas. Since Ranger launches had been delayed before by booster problems, technicians rushed to make sure nothing of the sort would delay Ranger 5's mission.

Tracking of [[Mariner 2]] was an ongoing job during this time and since NASA's [[Deep Space Network|deep space tracking networks]] could not handle both probes at once, it was decided to switch attention to Ranger 5 for its short mission.

After two launch attempts were aborted, one due to an electrical short in the probe and the other due to weather concerns, the go to fly was given for October 18. Liftoff took place at 12:59 PM EST and the [[Atlas-Agena|Atlas]] soon vanished into an overcast gray sky. A malfunction of the guidance system rate beacon at T+93 seconds resulted in noisy track rate data, but, unlike Ranger 3, discrete commands were received and issued by the guidance system properly. The Agena reached orbit successfully and began the burn to place Ranger 5 on a translunar trajectory.

Soon, however, high temperatures were detected in the computer system, and shortly afterwards, power generation from the solar panels ceased. The gamma ray detector was turned on, but the computer did not issue the command to align the spacecraft with Earth. Then the telemetry receivers at the tracking stations in Australia and South Africa malfunctioned, returning garbled data. It was obvious that an electrical short had disabled the [[solar panel]]s, which meant that Ranger 5 now had only a few hours before it would run out of battery power. JPL technicians thought that they could still partially salvage the mission by firing the midcourse correction engine to ensure impact with the Moon, but they had to do it quickly before power ran out. Ground controllers sent commands to unfurl the [[high-gain antenna]] and align the probe for the midcourse burn, but during this time more electrical shorts apparently occurred because there was a momentary dropout from the telemetry transmitter. The midcourse engine was fired, but Ranger 5 exhausted its batteries halfway through the burn. The radio [[transponder]] and [[telemetry]] signals ceased, followed by uncontrolled tumbling of the probe. Ranger 5 passed 450 miles from the [[lunar surface]] en route to a permanent orbit around the [[Sun]]. Signals were still received from the tiny seismometer capsule until fading as the probe's distance from Earth became too great.
Mission controllers tracked it to a distance of {{convert|1.3|e6km|mi}}.<ref name=nssdc1/>

This was the third attempt to impact the lunar surface with a Block II Ranger spacecraft. On this mission, just 15 minutes after normal operation, a malfunction led to the transfer of power from solar to [[Battery (electricity)|battery]] power. Normal operation never resumed; battery power was depleted after 8 hours, and all spacecraft systems died. The first midcourse correction was never implemented, and Ranger 5 passed the Moon at a range of 724 kilometers on October 21 and entered [[heliocentric orbit]]. It was tracked to a distance of 1,271,381 kilometers. Before loss of signal, the spacecraft sent back about 4 hours of data from the gamma-ray experiment.<ref name=nssdc1/>