Scientific Questions about the Nature of Saturn - Essay Example

INTRODUCTION In thousands of years humans have viewed the sky with a lot of mystery on what lays beyond. Instruments have been invented to give a clear picture of the deep space that goes on to infinity. It was not enough to just view, spacecrafts have been sent to explore this deep space to satisfy human desire for knowledge of what lays beyond. The Cassini-Huygens mission was one of the most ambitious projects that have ever been undertaken to explore planet Saturn, and solve unanswered mysteries. In this essay the Cassini-Huygens mission is given an overall view. The Cassini mission was officially known as the Cassini-Huygens after two scientists; Christian Huygens, (1929-1965). He was a Dutch scientist and discovered Saturn rings in 1655 and its largest moon Titan. The other scientist is Jean-Dominique Cassini (1625-1712) who discovered Saturn’s satellites Lapetus, Rhea, Tethys and Diope. Then in 1675 he discovered the narrow gap separating Saturn’s rings which today is known as the Cassini Division. The Cassini-Huygens is a collaboration of three space administrations namely NASA of the United States of America, ESA of the European Union and ASI of Italy. The spacecraft was launched on October 15th 1997 on board Titan-IVB/Centaur at Cape Canaveral, United States. After a space voyage of seven years it arrived at Saturn in July 2004.The journey included four gravity assist maneuvers that served to increase the spacecrafts velocity. The first maneuver was a fly-by Venus in April 1998 and a second one in June 1999. The third one was a fly-by earth on August 1999 and a final fly-by Jupiter on December 2000.This gravity assist maneuvers gave the spacecraft the speed it needed to get to the outer planetary system which could have required more than 68,040 kilograms of rocket fuel. Cassini is still in operation with an extended mission of up to 2017 while the Huygens probe landed on moon Titan after separation from the Cassini spacecraft after orbiting only thrice around Saturn. After seperation from the Cassini orbiter, it Titan took 22 days, travelling on a collision course to meet Titan at an angle of around 60 degrees, and travelled in its atmosphere for two and half hours. The Cassini orbiter had to perform a deviation maneuver to avoid plunging into Titan’s atmosphere. After Huygens landed on the Titan surface it took more than two and half hours of data gathering before it exhausted the power from its batteries. Mission Objectives The mission was to answers many scientific questions about the nature of Saturn and its moon Titan which has an atmosphere of its own. The main objectives were to investigate the source of Saturn’s energy that gives it 87% more energy than it receives from sunlight. Examine and give data that would shed light on the source of Saturn’s rings and their colors. The mission is also expected to give insight into the source of the moon Iapetus dark organic matter covering one side and why the moon Enceladus has such a smooth surface. The mission is to investigate what chemical activity is in Titan’s atmosphere and the source of its abundant methane gas that is associated with biological activity here on earth. The mission was also to establish whether there are lakes on Titan and any existence of complex compounds and pre-biotic molecules and also critically examine the magnetosphere of Saturn, its atmosphere and the atmosphere and composition of its rings. The presence of water and biological activity in Saturn and its moons is also an objective of this mission. Since the landing of the Huygens probe on Titan’s surface many of these objectives have been met with collected data and still others are still under investigation. Some data was lost when there was a malfunction of equipment on the Cassini orbiter that was supposed to switch on and receive transmission from the Huygens probe, however this data was picked by Antennas on earth and most of it reconstructed by scientists. Transmission from the Huygens probe was transmitted for two and half hours, two hours longer than initially expected. As Cassini continues to orbit around Saturn and its moons much data is being gathered and analyzed by scientist worldwide. Cassini Orbiter The Cassini spacecraft is more than 6.8 meters(22ft) high and more than 4meters(13ft) wide. The nature of the mission necessitated the complexity of the spacecraft. It has one thousand six hundred and thirty interconnected electronic components, twenty two thousand wire connections and 14 kilometers (8.7 miles) of wire cabling. The core control computer is a ML-STD-1750A Control system which was chosen because of its robustness in a hostile environment like the one Cassini mission is exposed to. With a distance of about 10 astronomical units away from earth it is not possible for real time control to take place because of the time lag of about seventy minutes from the spacecraft to Earth and the same time lag again from Earth to the spacecraft. The control of the craft relies heavily on the installed program for collision avoidance and prediction of the control team from Earth to steer around as it orbits around Saturn. The instruments on the Cassini orbiter gather data and send it back to earth. It has to gather and store data then send it back to Earth. To do this it has twelve sophisticated instruments that. The first is the plasma spectrometer (CAPS)that measurers the energy and electrically charged particles that the instruments encounters. It determines Satan’s magnetic field and molecules from its atmosphere. It will analyze Saturn’s magnetosphere, plasma and solar wind around it. The Cosmic Dust Analyzer (CDA) measures the size, speed and direction of tiny dust particles escaping from Saturn or its proximity. This may give information about the nature of the planet or nature of formation of the universe. This is to give insight into the mystery of what other celestial bodies are made of. Composite Infrared Spectrometer measures infrared waves from objects to determine their thermal properties, temperature and composition. It develops a three dimension profile of what Saturn’s environment looks like. It will give an intimate understanding that would involve the rings composition, surface temperature of the moons and altitude profile. The Ion and Neutral Mass Spectrometer (INMS) analyses charged and neutral particles. This will give the atmospheric composition and determine the kind of atoms and ions present in whatever sample it analyses. Imaging Science System instrument takes pictures in visible, near- ultraviolet and near-infrared spectrum. It has continued to take hundreds of images stored them and radioed them back to earth for processing and scientific interpretation. It has two cameras one that captures images in a small area but in high resolution and another one that captures images in a wide area but in lower resolution. Their spectrum ranges from 0.2 to 1.1 pixels in resolution. The Dual Technique Magnetometer maps Saturn’s magnetosphere to determine its general profile model in both strength and direction. The models are in three dimensions and include the moons of Saturn. Magnetospheric Imaging Instrument (MIMI) is a direct and remote instrument developing images of tiny particles trapped in Saturn’s magnetosphere. This data helps to understand its interaction with solar wind, ionosphere, the moons, overall configuration and dynamics of the magnetosphere and its influence on Saturn’s rings. The onboard radar is to map Titan’s surface and giving topographical information and capture any radio signals coming from Titans. It then will relay this information back to earth. This instrument is not limited to Titan only but to all the moons around Saturn. Radio and Plasma Ware Instruments (RPWS). This instrument measures plasma waves flowing from the sun’s ionized gases to Saturn natural radiation emissions and radio activity from the Saturn or its moons. Radio Science Subsystem (RSS) searches for gravitational forces and atmospheric properties by measuring changes in received signals back on earth. It uses radio antennas based on Earth to do this. Ultra-violet Imaging Spectrograph (UVIS) Captures images of objects by sensing ultra violet light reflected off such objects as rocks, clouds and liquids to give information about their structure and composition. It can take both spectral readings and spatial readings. It is particularly adept to determining composition of gasses. It then takes lots of pictures to create movies of how substances are moved around by forces. Visible and infrared Mapping Spectrometer (VIMS) is a remote sensing instruments that capturers images in both visible and infrared spectrum. It gives information about composition of moon surfaces. I t observes changes in cloud movements over long periods of time and gives the structural information of rings by means of observing light form either the sun or other stars pass through the rings. Cassini is powered by three Radioisotope Thermoelectric Generators (RTGs) which use heat from the natural decay of 260 pounds of plutonium -238 stored in form of plutonium dioxide. The current is generated by a thermocouple. Their excellent performance has allowed extension of the mission up to 2017. Huygens Probe The Huygens probe had six complex instruments that gathered a wide range of scientific data ones the probe landed on Titan. These instruments were the Huygens Atmospheric structure Instrument (HASI) which has a set of sensors. Accelerometers measured the forces in all directions as the probe descended through the atmosphere. The Permittivity and Electromagnetic Wave Analyzer measured electron and ion conductivities of the atmosphere and searched for electromagnetic wave activity. The HASI subsystem also had a microphone that recorded all acoustic events during the descent of the probe and subsequent landing. This gave for the first time audible recordings from another planetary system. Aerosol collector and Pyrolyser (ACP) collected aerosols for chemical composition analysis after extension of the sampling devices on entry into Titan’s atmosphere and landing. About 30 milligrams of the material was collected. Descent Imager/Spectral Radiometer (DISR) This instrument took images in a wide spectral range a few hundred meters before impact with the Titan Surface to get a spectral view of material on the Titan Surface. Doppler Wind Experiment (DWE) used radio signals to deduce atmospheric properties. As the probe descended, winds blowing hard swung it causing Doppler Effect and the atmosphere added attenuation. All these effects were detected in the radio signal. Gas Chromatography and Mass Spectrography (GCMS) quantized and analyzed chemicals present in the atmosphere. The gas high up in the atmosphere of Titan was taken and sampled later when the probe landed on the Titan surface. Surface Science Package (SSP) measured physical properties at the site of impact and provided unique information about its composition. Other sensors in this package measured temperature, thermal conductivity, heat capacity, speed of sound and permittivity of liquid material at impact. The Huygens probe was controlled and maintained form German by the Huygens Probe Operations center in Germany. The Cassini is controlled by the Jet Propulsion Laboratory and the whole process, communication and interpretation of data is made through NASA’s Deep space network. Findings Major findings have been made and discoveries and solving of mysteries is in progress up to date. Saturn has more than sixty moons some merely a few kilometers and others huge than our own moon. Scientists have developed a great interest mainly on Titan, Enceladus and Iapetus. Images taken of Saturn show the moons orbiting within the ring gaps and some taking materials from the ring gaps. Waves of orbiting moons are also visible. The Cassini scientists have discovered menagerie of clouds in Saturn’s deeper atmosphere about 30 km below the usual clouds seen on Saturn. This may be as a result of Saturn’s rings’ shadows on Saturn’s atmosphere that cool it down making clouds sink deeper to where they cannot be seen while powerful lightning storms ten thousand times stronger than those on earth occur in deeper huge columns nearly as large as the entire earth. Saturn’s magnetic rotation appears to be slowing down. Measurements of Saturn’s kilometric radiation used to determine internal rotation rate appears to be six minutes slower than the rate measured by Voyager an earlier spacecraft to flyby Saturn. This is however being interpreted to mean that Saturn’s Kilometric radiation is probably coupled with deep rotation rate and so is still under investigation. Cassini scientists have discovered a ring that encircles the planet like a spring near the F rings orbit. There are straw like clumps in the A rings that are several kilometers and an oxygen atmosphere just above the rings. Mechanisms that create “spokes” in the B ring that disappear and reappear are yet to be identified. Saturn’s F rings continues to change and a moon Prometheus was imaged stealing particles from the ring and a new moon was discovered lying between the rings causing the Keeler Gap. A new radiation belt discovered around Saturn between the inner edge of the D ring and the top of Saturn’s atmosphere is to be observed and investigated how it interacts with Saturn’s magnetosphere. Images of Iapetus obtained on December 31st 2004 by (VIMS) showed that the Iapetus surface had water ice and organic material covering its surface. Pictures of landslides on Iapetus make it share a common feature with planets like Earth and Mars. The landslide is seen to have travelled many kilometers from the basin scarp 15 km high indicating the surface is very fine grained. The trailing surface is observed to have been fluffed by mechanical forces and spreads up to 120km in diameter. Iapetus lacks an atmosphere that could give it enough precipitation for it to have particles deposited on it, scientists believe material on its surface may have been captured else where in Saturn’s planetary system by means of ballistic impact. Images of Saturn’s second largest moon show that it is strewn with craters. This shows that it may have experienced intense geological activity in its formation. Data from Titan show that activities that may have led to the formation of Earth’s habitable nature are much the similar with those on Titan. Images captured by DISR show images of meteorology and geology, complex drainage network from highlands to lowlands. The difference is that while on Earth the fluid flowing is water, on Titan it is liquid methane at a temperature of -170 degrees Celsius. Lakes and seas have been observed on the northern pole that are hundreds of thousands of square kilometers filled with mixtures of probably methane and ethane. During descent Huygens discovered a second ionosphere layer between 140km and 40 km with electrical signals peaking at 60km. Instruments may have recorded signature lightning. Haze was in the whole atmosphere contrary to expectations that towards lower altitudes it would clear out. However it reduced in density towards the surface allowing viewing from a distance of about 40km. On the Titan surface, the heat generated by the impact of Huygens on the surface led to bursts of methane being released from the surface. This was detected by the instruments GCMS and SSP. SISR surface images showed a riverbed composed of dirty water-ice pebbles that are rock like due to the extremely low temperatures. Dark matter was observed at the end of drainage channels as a result of it being washed by methane rain down drainage channels. It is interesting to observe that Titan has hydro-carbon particles instead of dirt, water-ice rocks and pebbles instead of silicate rocks, volcanoes spewing out very cold water-ice particles and ammonia instead of hot lava. The atmosphere is covered by dark haze that is gradually reducing in thickness as you approach its surface. This matter prevents observation by visible light from outer space. It is this dark matter that is washed down by methane rain and deposited on its surface. Argon 36 was identified on Titan’s atmosphere as the Huygens probe descended but not xenon or krypton. It was however in low abundance which is considered by the scientists interesting as Titan is 50% water ice by mass which is an efficient courier of noble gases. Argon 40 was detected at the surface of Titan indicating possibility of geological activity internally. The surface of Titan had organic compounds not seen in the atmosphere such as cyanogens and ethane indicating a complexity of Titan’s atmosphere and surface. Titan’s aerosols play an important role in determining atmospheric activity like cooling and heating. They influence creation of alternate cold and warm heating leading to circulation patterns that result in very strong winds. The ACP obtained direct measurements of the chemical make-up of these aerosols particles. Analysis of the products of pyrolisis, where organic materials are chemically decomposed by heating at a temperature of 600 degrees Celsius identified ammonia and hydrogen cyanide. Since ammonia is not present as a gas in the atmosphere it means the aerosols are a result of chemical reactions that produced complex organic molecules. They are not simply condensates. Titan hence offers an insight on early building blocks of life on earth. Cassini spacecraft detected an atmosphere around Enceladus during the fly-bys of 17 Feburuary and March 9 2005. On its south pole, which is almost free of impact craters its littered with house sized boulders which are curved by unique techtonique patterns found only in this region of the moon. The absence of impact craters on the South Pole suggests that it is younger than other terrains of Enceladus. On July 14th 2005 images from (CIS) COMPOSITE Infrared Spectrometer showed the south pole of Enceladus to have a warm south pole of about 85 Kelvin. This explained the presence of clouds of water vapor as some parts had temperatures of well up to 110 Kelvin. This makes Enceladus the only third solid body in the solar system after Earth and Jupiter’s moon Jo where internal geological process create hot spots on the surface. Recently scientists studying heating of Enceladus as a result of sheering of its ice outer shell discovered the ice particles are salt-rich and probably from an under sea of Titan that maybe located between an outer ice shell and a mineral-rich rocky core. According to a study published in Geophysical Research on March 4th 2007 Carly Howett said that the possibility of liquid water, a tidal energy source and observation of organic (carbon-rich) chemicals in the plume of Enceladus make the satellite a strong astrobiological interest. The moon Phoebe is made of materials that suggest it may have been made from materials that are from an outer solar system that got captured by Saturn’s gravitational force. Angioletta Coradini of the Inistituto di Fisica devo Spazio Interplanetario, CNR, Rome, said that Phoebe’s organic and cyanide composition are unlike any surface observed within the inner solar system. Data from he Cassini spacecraft suggest that Saturn’s majestic rings have their own atmosphere that is separate from the planet Saturn itself. This was determined by the ion and neutral spectrometer (INMS) and Cassini Plasma Spectrometer (CAPS). According to ESA website, Dr Andrew Coates co-investigator for CAPS, from the Mullard Space Science Laboratory (MSSL) at University College London said that water comes off the rings, it is split by sunlight; the resulting hydrogen and atomic oxygen are lost while the molecular oxygen is retained by gravitation forces and retained by the rings. Dr. Coates adds that the ring atmosphere was probably kept in check by gravitational forces, loss and supply of material from the rings. Cassini on September 24th-26th 2005 flew by Hyperion and Tethys and showed Hyperion to be sponge like and irregular in shape, it is observed to be spinning with a chaotic rotation and scientist say much of its interior is empty. Conclusion More data continues to be received and analyzed. Scientist continue to get deeper insight into what an early earth looked like and new strange ways that planet Saturn and its moons mainly Titan and Enceladus generate their own energy which may give us an idea of how to make our own in future. As more data is analyzed and the Cassini orbiter takes new images of the Saturn planetary system, scientist continue to find the signs of a primitive habitable like environment or one that has even the remotest possibility of having it. Other type data like cosmic dust give information about interactions with other systems apart from our solar system. The Cassini Huygens mission has brought a great deal of knowledge to humanity and continues to do so encouraging future explorations to this planetary system. But as of now, scientists are busy analyzing the overwhelming data they have continued to receive and the mission had been extended to about 2017, however as of now, engineers are investigating what caused it to go on safe mode. This has therefore caused unforeseeable changes to this great mission. Bibliography esa cassini-huygens. 2000-2010. European Space Agency. 11 April 2011 NASA. April 11th 2011. NASA. 11 April 2011 Cassini–Huygens. April 11th 2011. Wikipedia. 11 April 2011 < http://en.wikipedia.org/wiki/Cassini_spacecraft> Read More