Mariner program
The Mariner program NASA was used to explore the Earth-like planets in the solar system, ie Mercury, Venus and Mars. A total of ten space probes were launched 1962-1973.
Missions
Mariner until 5 and 10 were all Marinersonden probe pairs, that is, two sensors of the same type are relatively rapid succession, in the same so-called start window starts. Even with Mariner 10 was on another launch pad a rocket with a replacement copy for the case of a false start ready. The second copy was after the successful launch of Mariner 10 but not started. The spacecraft weighed between 200 ( at Mariner 1 and 2) and 1000 kg ( at Mariner 8 and 9), Mariner 1, 2 and 5 had no cameras on board. The probes Mariner 1-5 flew on the rocket Atlas - Agena into space, the probe Mariner 6 to 10 on an Atlas - Centaur, three of the probes suffered false starts.
Mariner 1 and 2
Mariner 1 and 2 were based on the Ranger lunar probes and were relatively quickly - in less than one year - designed to successfully send a probe to Venus before the USSR. The instrumentation was very modest due to the low power of the carrier rocket Atlas Agena B and included detectors for cosmic rays, dust and charged particles, magnetometers and for the exploration of Venus, an infrared and microwave radiometers. The biggest challenge was to build a spacecraft that could work 2500 hours in interplanetary space was. The Ranger probes on which Mariner 1 and 2 based should only be a few days running. Mariner 2 weighed 202.8 kg, of which 18.6 kg on the experiments. Built by probes from JPL for NASA, the U.S. National Aeronautics and Space.
Mariner 1 went on startup on July 22, 1962, when a faulty control program lost when the launcher came off the course and had to be blown up 290 seconds after the start. A developer had missed a slash in the specification of a program for controlling the drive and instead of smoothed values used raw data ( see Related links ), resulting in an erroneous and potentially dangerous dysregulation of the drive. Mariner 2 was launched on August 27, 1962 and discovered already on its way to Venus postulated by Ludwig Biermann in the 1950s solar wind. Very soon there were problems with the probe: After a course correction on 4 September 1962, the pressure increased in the nitrogen tank, with the evolution of fuel. Another course correction was no longer possible. The end of October eased the performance of the two solar panels, which all turned out on 15 November 1962. Since the probe is approached to the sun, however, enough of the current of the second panel in order to operate the probe. Other defects followed, however, could be resolved from the ground. When the probe happened on December 14, 1962 Venus at a distance of 34,773 km without problems and all measuring instruments, data that you joked at NASA, JPL would be the abbreviation for " Just Plenty of Luck " (Eng. " Just a lot of luck "). On January 3, 1963 Mariner 2 was made final.
The probe determined the temperature of Venus to 425 degrees Celsius, was not detected in water vapor of the atmosphere and the upper height of the cloud specific layer to about 55-80 km.
Mariner 3 and 4
Mariner 3 and 4 had as a goal the flyby of Mars. The slightly more powerful Atlas Agena D made it possible to bring a 260.8 kg mass spacecraft on the way. Of this total, 15.8 kg on the experiments. The span of the probes was 6.88 m and height 2.89 m. Mariner 3 and 4 were the first to a TV camera, but its picture quality was very modest. An image comprised only 200 lines with 200 points. The images were stored on the flight path on a tape recorder, which could take 22 pictures. The transfer to the earth lasted over 8 hours per image.
The experiments involved remains a magnetometer, and various detectors for dust, charged particles and high-energy rays. These were also active during the flight to Mars. Half of these experiments fell in the Mariner 4 but already on its way to Mars.
Mariner 3 was launched on November 5, 1964. First time you put a new lightweight payload fairing of fiberglass reinforced plastic one. However, this melted by the heat of friction during ascent and remained on the probe stick. So the solar panels could not be extended and the probe had to remain in Earth orbit as it was too heavy even to go to Mars.
For the Mariner 4 launch was postponed and made a new fairing made of metal. Mariner 4 was launched on 28 November 1964 and flew the first underground space probe to land on Mars on July 15, 1965 at a distance of 9844 kilometers over. The probe took within 22 minutes to 22 pictures that were sent to Earth during the next few days. They showed a very moon-like Mars, but accounted for only 1% of the surface. It was also found that Mars has no or only a very weak magnetic field. The atmosphere has a base pressure of at most 30 mbar, and is 80 to 100 % of carbon dioxide and up to 16 % nitrogen and 8 % argon. Until 20 December 1967, a communication with the probe was possible.
Mariner 5
Mariner 5 was one of the two single missions in the program. It started a reserve copy of Mariner 3 and 4 for Venus. Changes in the probe resulted from the reduced distance from the sun of Venus. So a shield was attached to the bottom of the probe and reduces the solar panels. 245 kg spacecraft had a wingspan of 5.48 m and was 2.89 m high. The equipment for experiments weighed 15.8 kg. They were largely identical to those on board Mariner 3 and 4, but replacing a UV photometer the camera, and an additional building block made it possible to send a carrier wave with well-defined frequency.
Main mission, launched on June 14, 1967 probe was to disappear behind the Venus and to send a pure carrier wave whose frequency, phase and amplitude changes were measured on Earth. This could be used to determine properties of the ionosphere, atmosphere and internal composition of Venus.
Mariner 5 graduated on 19 October 1967 a successful flyby of the planet Venus and delivered numerous scientific data. It was found that Venus has a mean radius of 6051.8 km, is hardly flattened and the atmosphere must be very tight. The base pressure was set to 75 to 100 bar, the estimated surface temperature of 500 degrees Celsius.
Mariner 6 and 7
Mariner 6 and 7 were two more flyby probes. You should pass the Mars and make more and better resolution images than Mariner 4. The availability of the Atlas - Centaur launch vehicle allowed it to start much heavier probes. Mariner 6 and 7 were respectively 412.8 kg heavy, of which 57.6 kg on the experiments. For the first time there was also a control program on board. They renounced the experiments to investigate the interplanetary space probes and gave the two cameras, an ultraviolet spectrometer and an infrared radiometer on the way.
Mariner 6 was launched on 24 February 1969. She was sent on a very fast track and passed Mars on July 31, 1969. Thereby, the flyby distance of 3430 kilometers, was significantly lower than that of Mariner 4 allowed this and further improvements of transmitters and receivers to transmit an image in a matter of minutes. The probe made initially from a distance 50 pictures of Mars that showed the entire planet, then the flyby another 25 shots with the wide-angle camera, which were transferred directly.
Mariner 7 was launched on 27 March 1969. On 2 August 1969, the probe produced 93 shots on during the approach, covering two full rotations of the planet. During the passage, there was a further 33 pictures. Both probes passed the Mars in the southern hemisphere and mapped 20 percent of the surface. The ground pressure and temperatures could be determined more accurately. In recordings from Mariner 7 was the size of Phobos, the larger of Mars' two moons, are determined to 22.4 × 17.6 km. The photos that have just been published once one or two weeks after the return of the Apollo 11 astronauts, so met a sensitized public.
Mariner 8 and 9
Mariner 8 and 9 had the task for the first time in an orbit around Mars to wheel. The probes were based on Mariner 6 and 7, but were much harder because now were added also an engine and fuel for braking into Mars orbit. Mariner 8 and 9 each weighing 998 kg, of which 63.1 kg was attributable to the instruments. These were improved versions of those from Mariner 6 and 7, supplemented by an infrared spectrometer. In particular, the camera has been improved and made much sharper pictures than Mariner 6 and 7
Originally Mariner 8 should conduct a mapping of the planet with the wide-angle camera and shoot Mariner 9 particularly interesting areas with the telephoto camera in detail. After the false start of Mariner 8 on 8 May 1971 caused by a defective diode in the control computer of the Centaur upper stage, the program of Mariner 9 was changed. Mariner 9 was launched on 30 May 1971. November 14, 1971, the probe fired its engine for 915.6 seconds and waved in a 1397 km x 17,616 km orbit with an inclination of 64.28 degrees. Mariner 9 became the first underground probes at all, the einschwenkte in orbit around another planet. At this time raged on Mars is the largest dust storm since 1953, so the first photos showed only the peaks of some high volcanoes. At the beginning of 1972, the atmosphere cleared up, and Mariner 9 began to map Mars. Surface temperatures were determined and the composition of the atmosphere.
The time between the observation of detail regions was extended from five to 17 days. Every day made the probe over 21 hours recording ( max. 36 pieces) on the tape recorder and transferred them during the rest of three hours to the earth. Most of the pictures were taken near the mars next point. Already in July 1971 we noticed a leak in the nitrogen tank, who served with 176 bar pressure for position control. Thus, the mission duration was limited, for now, the probe lost constantly nitrogen, and decreased the pressure. After 349 days in orbit, the gas pressure was on October 27, 1972 depleted and the probe was turned off. She had until then 7329 images transmitted to Earth.
Mariner 10
Mariner 10, the last of the Mariner series, was again a flyby probe - but with very complex path maneuvers. You should first visit the sun next planet Mercury. As the first spacecraft ever they took advantage of a planet, in this case, the Venus, a swing-by maneuvers, which submitted the probe to Mercury. To get from the Earth near the Sun to Mercury, a probe must train their energy that she has noticed by the web speed of the earth to reduce about 60 percent. By decelerating the swing-by the cheaper Atlas - Centaur could be used as a launcher instead of the Titan IIIC. In addition, the data were transferred much more quickly by the use of the X- band. The probe was based on the bus from Mariner 8 and 9, but had to be modified for the low sun distance. The total start mass was 503 kg. It was built to probe of Boeing. The instruments, including two cameras, weighed 78.2 kg and contained seven experiments.
After starting on November 3, 1973, the probe passed on 5 February 1974, the Venus, of which she was wearing over 4165 images. Mercury was first happened March 29, 1974 at a distance of 705 km, with 2450 images were transmitted. Thus, a space probe arrived at the planet for the first time. Mercury turned the probe into a 176 -day orbit around the sun. Since Mercury orbits the Sun itself in 88 days, to probe and Mercury met after 176 days later at the same point of the Mercury orbit. However, Mercury rotates in 59 days once around its own axis, and so he turns after every three sidereal rotations (star days ) the sun again the same page. The next meeting on September 21, 1974 took place at a greater distance of about 50,000 km, so as not to affect the trajectory of the probe by the outgoing Mercury gravity. The last meeting on March 16, 1975, however, led up to 375 km to connect with Mercury, in order to study the magnetic field better. On 24 March 1975, the stocks of fuel were exhausted and the probe was turned off. Mariner 10 was until March 2011 ( the arrival of MESSENGER at Mercury ) was the only Mercury probe.
Results
- The Mariner program was considered a great technical success: There were only three false starts ( success rate 70 %), which was a very good value for the pioneering days of space flight.
- The U.S. could deliver all the inner planets from the USSR was the first nation recordings.
- The planet Mercury was detected by Mariner 10 to 45 % photographically ( about 9000 frames).
- The planet Venus was explored by Mariner 2, 5 and 10, although the U.S. interest in this planet then subsided noticeably. The planet was later explored in more detail by the Soviet Union. Only one probe, Mariner 10, also made images of the planet.
- The planet Mars has attracted more attention: Mariner 4 explored about 1 % of the surface, Mariner 6 and 7 about 20%. Through the first Mars orbiter, Mariner 9, succeeded in creating the first map of Mars, albeit of poor quality. Life as on Earth, which reported after the Mariners, has not been possible on Mars.