miércoles, 17 de octubre de 2012

NASA - NASA History Program Office to Host Solar system Exploration @ 50 Symposium

NASA Symposium Marks 50 Years Of Solar System Exploration
 WASHINGTON -- Media representatives are invited to attend a NASA History symposium about past, present and future solar system exploration. The event takes place Oct. 25-26 from 8:30 a.m. - 5 p.m. EDT, at the Lockheed Martin Global Vision Center in Crystal City, Va.

The event is free and open to the public with prior registration. The deadline for registration is Friday, Oct. 19 at 5 p.m. The two-day event will be streamed live on the agency's website at:

The Solar System Exploration @ 50 Symposium will explore the milestones of our 50-year history of planetary exploration, what we have learned, and how we have learned it. The symposium is sponsored by the NASA History Program Office and the Science Mission Directorate at NASA Headquarters in Washington, NASA's Jet Propulsion Laboratory in Pasadena, Calif., and the Smithsonian's National Air and Space Museum in Washington.

Media representatives interested in attending should email Dwayne Brown at
Yvette Smith at
For a complete list of speakers and to register, visit:  
 
National Space Science Data Center Header

Mariner 2

NSSDC ID: 1962-041A

Description

The Mariner 2 spacecraft was the second of a series of spacecraft used for planetary exploration in the flyby, or nonlanding, mode and the first spacecraft to successfully encounter another planet. Mariner 2 was a backup for the Mariner 1 mission which failed shortly after launch to Venus. The objective of the Mariner 2 mission was to fly by Venus and return data on the planet's atmosphere, magnetic field, charged particle environment, and mass. It also made measurements of the interplanetary medium during its cruise to Venus and after the flyby.

Spacecraft and Subsystems

Mariner 2 consisted of a hexagonal base, 1.04 meters across and 0.36 meters thick, which contained six magnesium chassis housing the electronics for the science experiments, communications, data encoding, computing, timing, and attitude control, and the power control, battery, and battery charger, as well as the attitude control gas bottles and the rocket engine. On top of the base was a tall pyramid-shaped mast on which the science experiments were mounted which brought the total height of the spacecraft to 3.66 meters. Attached to either side of the base were rectangular solar panel wings with a total span of 5.05 meters and width of 0.76 meters. Attached by an arm to one side of the base and extending below the spacecraft was a large directional dish antenna.
The Mariner 2 power system consisted of the two solar cell wings, one 183 cm by 76 cm and the other 152 cm by 76 cm (with a 31 cm dacron extension (a solar sail) to balance the solar pressure on the panels) which powered the craft directly or recharged a 1000 Watt-hour sealed silver-zinc cell battery, which was used before the panels were deployed, when the panels were not illuminated by the Sun, and when loads were heavy. A power-switching and booster regulator device controlled the power flow. Communications consisted of a 3 Watt transmitter capable of continuous telemetry operation, the large high gain directional dish antenna, a cylindrical omnidirectional antenna at the top of the instrument mast, and two command antennas, one on the end of either solar panel, which received instructions for midcourse maneuvers and other functions.
Propulsion for midcourse maneuvers was supplied by a monopropellant (anhydrous hydrazine) 225 N retro-rocket. The hydrazine was ignited using nitrogen tetroxide and aluminum oxide pellets, and thrust direction was controlled by four jet vanes situated below the thrust chamber. Attitude control with a 1 degree pointing error was maintained by a system of nitrogen gas jets. The Sun and Earth were used as references for attitude stabilization. Overall timing and control was performed by a digital Central Computer and Sequencer. Thermal control was achieved through the use of passive reflecting and absorbing surfaces, thermal shields, and movable louvers.
The scientific experiments were mounted on the instrument mast and base. A magnetometer was attached to the top of the mast below the omnidirectional antenna. Particle detectors were mounted halfway up the mast, along with the cosmic ray detector. A cosmic dust detector and solar plasma spectrometer detector were attached to the top edges of the spacecraft base. A microwave radiometer and an infrared radiometer and the radiometer reference horns were rigidly mounted to a 48 cm diameter parabolic radiometer antenna mounted near the bottom of the mast. All instruments were operated throughout the cruise and encounter modes except the radiometers, which were only used in the immediate vicinity of Venus.

Mission Profile

After launch and termination of the Agena first burn, the Agena-Mariner was in a 118 km altitude Earth parking orbit. The Agena second burn some 980 seconds later followed by Agena-Mariner separation injected the Mariner 2 spacecraft into a geocentric escape hyperbola at 26 minutes 3 seconds after lift-off. Solar panel extension was completed about 44 minutes after launch. On 29 August 1962 cruise science experiments were turned on. The midcourse maneuver was initiated at 22:49:00 UT on 4 September and completed at 2:45:25 UT 5 September. On 8 September at 17:50 UT the spacecraft suddenly lost its attitude control, which was restored by the gyroscopes 3 minutes later. The cause was unknown but may have been a collision with a small object. On October 31 the output from one solar panel deteriorated abruptly, and the science cruise instruments were turned off. A week later the panel resumed normal function and instruments were turned back on. The panel permanently failed on 15 November, but Mariner 2 was close enough to the Sun that one panel could supply adequate power. On December 14 the radiometers were turned on. Mariner 2 approached Venus from 30 degrees above the dark side of the planet, and passed below the planet at its closest distance of 34,773 km at 19:59:28 UT 14 December 1962. After encounter, cruise mode resumed. Spacecraft perihelion occurred on 27 December at a distance of 105,464,560 km. The last transmission from Mariner 2 was received on 3 January 1963 at 07:00 UT. Mariner 2 remains in heliocentric orbit.

Scientific Results

Scientific discoveries made by Mariner 2 included a slow retrograde rotation rate for Venus, hot surface temperatures and high surface pressures, a predominantly carbon dioxide atmosphere, continuous cloud cover with a top altitude of about 60 km, and no detectable magnetic field. It was also shown that in interplanetary space the solar wind streams continuously and the cosmic dust density is much lower than the near-Earth region. Improved estimates of Venus' mass and the value of the astronomical unit were made.
Total research, development, launch, and support costs for the Mariner series of spacecraft (Mariners 1 through 10) was approximately $554 million.
 NASA

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JFK Receives Mariner Model

William H. Pickering, (center) director of NASA's Jet Propulsion Laboratory, presents a model of the Mariner spacecraft to President John F. Kennedy in 1961. NASA Administrator James Webb is standing directly behind the model. 
Image Credit: NASA
 Atlas Agena - the docking target for Gemini spacecraft. Atlas Rocket Gallery. NASA
http://exploration.grc.nasa.gov/education/rocket/gallery/atlas/atlas1.html

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Mariner 2

Mariner 2 was the world's first successful interplanetary spacecraft. Launched Aug. 27, 1962, on an Atlas-Agena rocket, Mariner 2 passed within about 34,000 kilometers (21,000 miles) of Venus, sending back valuable new information about interplanetary space and the Venusian atmosphere. Mariner 2 recorded the planet's temperature for the first time, revealing the its very hot atmosphere of about 500 degrees Celsius (900 degrees Fahrenheit). The spacecraft's solar wind experiment was the first to measure the density, velocity, composition and variation over time of the solar wind.

Subsequent missions have further explored Venus, detecting electrical activity, which was confirmed by the European Space Agency's Venus Express earlier this week.  
Image Credit: NASA/JPL

NASA’s exploration of the solar system began 50 years ago with the successful launch of the Mariner 2 spacecraft on Aug. 27, 1962. The spacecraft launched aboard an Atlas-Agena rocket and passed within about 21,000 miles (34,000 kilometers) of Venus, sending back valuable new information about interplanetary space and the Venusian atmosphere. The mission recorded the planet's temperature for the first time, revealing its very hot atmosphere of about 500 degrees Celsius (900 degrees Fahrenheit). The spacecraft's solar wind experiment was the first to measure the density, velocity, composition and variation over time of the solar wind. The probe stopped transmitting in 1963 after delivering a wealth of scientific information.

Since the success of Mariner 2, NASA successfully has launched a host of solar system mission, notably Cassini to study to Saturn and its moons, and multiple missions to Mars, the latest of which, Curiosity, landed on the Red Planet in August 2012.

To commemorate the 50th anniversary of this, the first successful planetary mission, the NASA History Program Office, in conjunction with the Division of Space History at the National Air and Space Museum, the NASA Science Mission Directorate and the Jet Propulsion Laboratory will host a symposium on Oct. 25-26, 2012. The event will be held at the Lockheed Martin Global Vision Center, 2121 Crystal Drive, Arlington, Va. Participation is open to the public, although registration will be required.

The Solar System Exploration @ 50 symposium will explore issues of interest to scholars, media and the public covering the 50-year history of the space age, what scientists have learned about the other bodies of the solar system and the process whereby they have learned it.

This symposium seeks to pursue broader questions relating to the history of planetary exploration, such as various flight projects and their broader implications for the exploration of other solar system bodies; development of space science disciplines and institution building; the relationships of organizations/international, civil/military, etc., one to another; as well as the relationship between robotic exploration and human spaceflight. The symposium participants also will offer analyses of the science of solar system origins and evolution.

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Guillermo Gonzalo Sánchez Achutegui
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ayabaca@hotmail.com
ayabaca@yahoo.com  
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