FLY BY ON ENCELADUS

ENCELADUS FLYBYScott CoughlinBrian LachHolden Martin Outline1. Background2. Applications for LifeGeological StructureTiger StripesChemicals Found3. Previous Flyby MissionsVoyager 1 and 2Cassini4. Cassini 2.0New ApproachesNew Technology5. LogisticsCost/Budget

BackgroundEnceladus is Saturns 14th moon in terms of distanceEnceladus is 500 km in diameter making it Saturns sixth largest moonEnceladus travel in Saturns E-Ring

3Some More Background!

Saturns E-RingEnceladus circles with Saturns E-ring and many people believe that the water jets (or plumes) that come from Enceladus actually are the cause of Saturns E-ring

Numerous mathematical models show that such a ring is unstable, with a lifespan between 10,000 and 1,000,000 years. Therefore, particles composing it must be constantly replenished. Enceladus is orbiting inside this ring, in a place where it is narrowest but present in its highest density.The E Ring is the widest and outermost ring of Saturn. It is an extremely wide but very diffuse disk of microscopic icy or dusty material, beginning at the orbit of Mimas and ending somewhere around the orbit of Rhea, though some observations suggest that it extends beyond the orbit of Titan, making it 1,000,000km wide. However, numerous mathematical models show that such a ring is unstable, with a lifespan between 10,000 and 1,000,000 years. Therefore, particles composing it must be constantly replenished. Enceladus is orbiting inside this ring, in a place where it is narrowest but present in its highest density. Therefore, several theories suspected Enceladus to be the main source of particles for the E Ring. This hypothesis was supported by Cassini's flyby.

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Geological Features1.) Silicate Core 2.) Outer water-ice-rich mantle3.) Plate Tectonics4.) Diapir5.) Giant Plumes/Geysers 6.) Tiger StripesIn south polar regionsWarmest part of planet

Why Enceladus?In May 2011 NASA scientists at an Enceladus Focus Group Conference reported that Enceladus "is emerging as the most habitable spot beyond Earth in the Solar System for life as we know it.Properties: Liquid water, organic carbon, nitrogen [in the form of ammonia], and an energy source.This is key because according to Chris McKay, an astrobiologist at NASA's Ames Research Center, besides Earth, "there is no other environment in the Solar System where we can make all those claims."The PlumesDramatic plumes, both large and small, spray water ice out from many locations along the tiger stripes near the south pole of Saturn's moon Enceladus. From right to left, the four major stripes are Damascus, Baghdad, Cairo and Alexandria sulci.

Analysis of PlumesJack Hunter (J.H.) Waite, of the Southwest Research Institute in San Antonio, Texas and his colleagues say ammonia detected in the jets from Enceladus south pole provides the strongest evidence yet for the existence of liquid water beneath the surface. Analyses of Cassini through the heart of the plumes show that 99% of the mass of plume ice-particles is salt-rich. This implies that the water in plume ice came from salty liquid water somewhere beneath the surface, say researchers. Below is the chemical measurement of one of these plumes.

This is a chemical measurement contains all of the three things mentioned earlier: Liquid water, organic carbon, nitrogen. Tiger Stripes

Data from Cassini's composite infrared spectrometer of Enceladus' south polar terrain, which is marked by linear fissures, indicate that the internal heat-generated power is about 15.8 gigawatts, approximately 2.6 times the power output of all the hot springs in the Yellowstone region, or comparable to 20 coal-fueled power stations.The image above shows that at least three of the south polar fractures are active along almost their full lengthsthe fourth one, on the right, was only partially covered by this scan. The level of activity varies greatly along the fractures. The warmest parts of the fractures tend to lie on locations of the plume jets identified in earlier images. The main "tiger stripe" fractures are not the only sources of heat, however; additional warm spots are seen in the upper right part of the scan. The warm regions are probably concentrated within less than a few hundred meters (a few hundred yards) of the fractures, and their apparent width in this image results from the relatively low resolution of the infrared data.

10More on Tiger StripesApril 14, 2012- The Fields, Particles and Waves instruments (a.k.a. MAPS) are prime (particularly the ion and neutral mass spectrometer [INMS]) to study the composition, density, three-dimensional structure and variability of plumes; with E-14, and E-17, this flyby provides good coverage of south polar regions.

The Tiger StripesHow Hot is Hot?-140 F or -90 CMay seem cold but is about 270 degrees warmer then the rest of the planetIt is formed through a combination of tidal heating and pressurized liquid which then shoots out water vapor and ice particles

Previous MissionsVoyager 1 and 2Launched in 1977. Flew by Saturn system in 1980 and 1981, respectively.First to place Enceladus on the map for possible places of life in our solar system.CassiniLaunched October 15, 1997.Flown by Enceladus 33 times an average of 34480 km away but with some flybys as close as 25 km.Most recent just yesterday May 2, 2012.Voyager 1 and Voyager 2In the early 1980s, the two Voyager spacecrafts passed Enceladus and found essentially all of the basic background information stated earlier.500 km in diameterSurface reflected almost 100 percent of sun light, etc.Voyager 1 and 2 were important because they catapulted Enceladus to the forefront of prospective places for life in our solar system.

Cassini-HuygensObjectives regarding Enceladus:Determine the characteristics and geological history of EnceladusDetermine the different physical processes that created the surface of EnceladusInvestigate composition and distribution of surface materials on Enceladus particularly dark, organic material, and condensed iceDetermine the bulk composition and internal structure of EnceladusInvestigate interaction of Enceladus with Saturns magnetosphere and ring system

First Flybys July 14 & March 9, 2005During the first two close flybys (175km & 500km) of Enceladus, Cassini discovered a deflection in the local magnetic field, and measurements taken pointed to ionized water vapor as the main component.Cassini observed water ice geysers erupting from the south pole, giving credibility to the idea that Enceladus supplies the particles of Saturns E ring.It was hypothesized that pockets of liquid water exist near the surface making Enceladus one of the few bodies in the solar system to contain liquid water.Second Flyby March 12, 2008This close flyby (within 50km of the surface) passed through the plumes of Enceladus southern geysers and detected water, carbon dioxide, and various hydrocarbons using a mass spectrometer.This flyby also involved mapping surface features that were at a much higher temperature than their surroundings with an infrared spectrometer.A cosmic dust analyzer was intended to be used to collect data, but malfunctioned.Third Flyby November 21, 2009The third flyby came within 1600km of the surface.The composite infrared spectograph (CIRS) was expected to map thermal emission from the tiger stripe Baghdad Sulcus.Data and images returned were expected to help create the most detailed image of the southern part of the moons Saturn facing hemisphere and a contiguous thermal map of one of the tiger stripe features.

Image of Baghdad SulcusMay 2, 2012Flybys are happening continually even as recent as yesterday!This flyby is a radio science (RSS) gravity flyby, which is designed to understand the internal structure of Enceladus, particularly the concentration of mass under the south polar region. RSS will have its usual three periods of observation: two wings and closest-approach. The MAPS pointing will be optimized to gather data near closest approach.

New DiscoveriesCassini has been doing wonders for data collection about Enceladus. Information concerning the plumes has all come from Cassini.Infrared imaging has allowed a new model of the interior temperature and design of Enceladus to be made.

Most importantly it has affirmed that there is most likely liquid water on Enceladus, the most important discovery for a planet to potentially have life.

NASA provides daily images from CassiniWhat Can Be Done?Cassini 2.0Cassinis instruments only revealed basic information concerning the prospects of life.New instruments would help confirm findings about the plumes and the hot spots.Possible ApproachesOne-way mission:Multiple flybys of Enceladus and other moonsCrash the orbiter at end of missionLander probe (Huygens probe)

Jet mission: 16 flybys of Enceladus and Titan (futureplanets.blogspot.com/2011/03/jet-cost-capped-titan-enceladus.html)

Closest Cassini Enceladus flyby: 50 km (http://en.wikipedia.org/wiki/Cassini%E2%80%93Huygens#Venus_and_Earth_fly-bys_and_the_cruise_to_Jupiter)

Huygens: 319 kg; Huygens separated from the Cassini orbiter on December 25, 2004; landed on titan22Other Approaches Round-trip flight:More focused mission to collect plume materialAnalyze plume material in lab on Earth

Picture: failed Russian Mars probe; failed to leave Earth; crashed back down; This artist's concept shows fuel from Russia's failed Mars probe Phobos-Grunt burning from a ruptured fuel tank as the spacecraft re-enters the atmosphere. (http://www.space.com/14242-russia-spacecraft-phobos-grunt-crash-earth.html)23Getting there (and maybe back)1.2 billion km (~8 AU) to Saturn at closest pointCassini: 7 years travel time at up to 45 km/sec

Getting there:multiple gravity boosts from Venus, Earth, and Jupiter reduces travel timeRequires special alignment of planets; small launch window

Getting there: initial launch into space2 gravity boosts from venus, one from earth, and one from jupiter; see picturespecial alignment of planets that wont happen for another 600 years; not feasible until 2030sWithout gravity boost : 9-10 years

gravity boost:speed of spacecraft relative to planet is same before and after capture, but spacecraft acquires the momentum of the planet revolving around Sun. To gain interplanetary momentum while already in flight, the trajectory of the Cassini mission included several gravitational slingshot maneuvers: two fly-by passes of Venus, one more of the Earth, and then one of the planet Jupiter. using special alignment of planets that wont happen for another 600 years (http://www.youtube.com/watch?v=hRjaBORkhog)

But it may be too late to get a mission there the fast way, via a gravity boost from Jupiter. This would cut the journey time from ten years to as little as seven, but the next Jupiter-assist window hits its peak in 2015-17, and then closes until the 2030s (But it may be too late to get a mission there the fast way, via a gravity boost from Jupiter. This would cut the journey time from ten years to as little as seven, but the next Jupiter-assist window hits its peak in 2015-17, and then closes until the 2030s)

September 2020 and arriving at Saturn in October 2029, delivering up to 6265 kg to Saturn approach, and an EVEEGA-SEP backup trajectory launching in 2021 for a 2031 arrival. Transfer times to Saturn are longer than for the Cassini-Huygens mission because in the 20182022 launch period Jupiter gravity assists to Saturn are not available.During SEP thrusting, the flight system makes use of an inner planet gravity assist trajectory that delivers it to Saturn approxi- mately 9 years after launch. When the SEP stage is no longer viable due to increasing distance from the sun, about five years after launch, the SEP stage is jettisoned using the highly reliable fault tolerant Superzip interface which routinely releases payloads from launch vehicles. Upon Saturn arrival the orbiters chemical propulsion system places the flight system into orbit around Saturn, followed by approximately two years of Saturn tour sci- ence.(http://sci.esa.int/science-e/www/object/index.cfm?fobjectid=44033)24Staying there:Engine to slow spacecraft into Saturns orbitSteer mainly with Titan flybys

Getting Back:More gravity boosts!Extra weight for heat shield, parachute, fuel

Staying there:- Need to use main engine to slow probe into Saturns orbit

power source: Because of Saturn's distance from the Sun, solar arrays were not feasible as power sources for this space probe.[20] To generate enough power, such arrays would have been too large and too heavy.[20] Instead, the Cassini orbiter is powered by three radioisotope thermoelectric generators (RTGs), which use heat from the natural decay of about 33 kilograms (72 pounds) of plutonium-238 (in the form of plutonium dioxide) to generate direct current electricity via thermoelectrics.[20]plenty of power for the spacecrafts lifetime

Cassini fired main rockets for 95 minutes to slow probe(http://articles.cnn.com/2004-07-01/tech/cassini.orbit_1_cassini-program-manager-saturn-orbit-nasa-s-cassini?_s=PM:TECH)

Engines: http://www2.jpl.nasa.gov/basics/bsf11-4.php

25Purpose of Cassini 2.0Assess astrobiological potential and geology of Enceladus

Plumes and E-ring:Confirm liquid water is source of plumesLook for biomarkers, elements for lifeex: confirm fraction of CO vs. N2 vs. hydrocarbons

Further study of Enceladus surface

Biomarker: substance - such as an element, isotope, or molecule, or phenomenon - that provides scientific evidence of past or present life.

http://futureplanets.blogspot.com/2011/03/jet-cost-capped-titan-enceladus.html:Science: The three goals of the mission are to determine the processes that have shaped and are shaping Titan, to assess the astrobiological potential of Enceladus and Titan, and to investigate the formation and evolution of Enceladus and Titan. These three goals are then detailed in eleven science objectives and thirty-one science questions that cannot be answered by the Cassini mission. Three examples are given. First, the Cassini mission has discovered that mass 28 in Enceladus plume has possible CO, N2 and/or hydrocarbon components. JET would confirm what fraction is CO vs. N2 vs. hydrocarbons. Second, the Cassini-Huygens mission has discovered that rivers and valleys are carved into plateaus and mountains. JET would search for sedimentary layering in valleys to determine the history of the flows.26Titan Saturn System Mission (TSSM)Joint NASA/ESA proposal for an exploration of Saturn, Titan, and Enceladus

Minimum of seven close Enceladus flybys

Exploring the composition of the Enceladus plumes and whether the source region is liquid water http://en.wikipedia.org/wiki/Titan_Saturn_System_Mission

Titan Saturn System Mission (TSSM) was a joint NASA/ESA proposal for an exploration of Saturn and its moons Titan and Enceladus,

Mission to Jupiter and its moons was given priority in 2009 over this misison27Cassini InstrumentsOptical remote sensing- detect electromagnetic light (infrared, visible, and ultraviolet; low- and high-res)

Fields, particles, and waves- study dust (plumes), plasma, and magnetic fields

Microwave remote sensing- use radio waves to map atmospheres and surface

Different instruments: http://saturn.jpl.nasa.gov/spacecraft/cassiniorbiterinstruments/

12 instruments

Optical sensing: low-res for wide views, high-res for closeups

ALSO HAS communications antenna TO RETURN DATA28Cassini 2.0 Instruments ROSINA (Rosetta Orbiter Spectrometer for Ion and Neutral Analysis) Mass SpectrometerReveal chemical composition of Enceladus plumesCharacterize complex organic molecules with a 10 larger mass range, 100 higher resolution, and 1000 better sensitivity than Cassini Search for biomarkers: carbon-12,-13 ratio

BEST LINK: http://futureplanets.blogspot.com/2011/03/jet-cost-capped-titan-enceladus.html

Rosetta is a robotic spacecraft of the European Space Agency on a mission to study the comet 67P/ChuryumovGerasimenko. ROSINA (Rosetta Orbiter Spectrometer for Ion and Neutral Analysis). The instrument consists a double focus magnetic mass spectrometer DFMS and a reflectron type time of flight mass spectrometer RTOF. The DFMS has a high resolution (can resolve N2 from CO) for molecules up to 300 amu. The RTOF is highly sensitive for neutral molecules and for ions.[2- Improvement on Cassinis Ion and Neutral Mass Spectrometer (INMS)

Cassini is only equipped to find the building blocks of life, not more complex molecules amino acid L isomers

CDA: http://saturn.jpl.nasa.gov/news/newsreleases/newsrelease20110622/

This plot shows results from Cassini's ion neutral mass spectrometer and cosmic dust analyzer, obtained during the spacecraft's close approach to Enceladus on July 14, 2005.

Within a minute of that closest approach, the two instruments detected material coming from the surface of the moon. The ion neutral mass spectrometer measured a large peak in the abundance of water vapor at approximately 35 seconds before closest approach to Enceladus, as it flew over the south polar region at an altitude of 270 kilometers (168 miles).

The high rate detector of the cosmic dust analyzer observed a peak in the number of fine, powder-sized icy particles coming from the surface approximately a minute before reaching closest approach, at an altitude of 460 kilometers (286 miles).

The character of these detections is very similar to the venting of vapor and fine, icy particles from the surfaces of comets when they are warmed as they near the Sun. On Enceladus however, it is believed that internal heat, possibly from tidal forces, is responsible for the activity. The close but different occurrences of the two detections are yielding important clues to the location of the vents and even the venting process.

But acetylene, methane, ethanol and acetate aren't biomarkers. What's needed, Oremland and McKay agree, is to examine the ratios of carbon's two stable isotopes: carbon-12 and carbon-13. Chemical and geophysical processes don't distinguish between the two. But the biological processes we know tend to favour the lighter isotope. Thus, if the methane coming from Enceladus is relatively rich in carbon-12, it's a strong sign of biological activity. Similarly, if the plume is emitting ethanol and acetate rich in light carbon, acetylene-eating bugs may be at work.

Amino acids might also reveal life, especially if they reproduce, or reverse, Earth life's overwhelming preference for 'L' isomers over their mirror image 'D' isomers, a skew not seen in abiotic processes. Any such bias would be "persuasive evidence for a biological origin," says McKay. (http://www.nature.com/news/2011/110531/full/news.2011.337.html)

Mock mission to Enceladushttp://www.airspacemag.com/space-exploration/FEATURE-enceladus.html#29Cassini 2.0 Instrumentshttp://futureplanets.blogspot.com/2011/06/enceladus-mission-options.html

Similarly, TIGER would provide 10 m/pix images of selected Enceladus tiger stripe fractures, permitting detailed thermal modeling.30The MissionLaunch 2016, arrive 2023Multiple flybys of Enceladus and TitanSample different South pole plumes on Enceladus, thermal mappingCost: $500 million (Cassini: ~$2.5 billion)

Cost: $425 million

Cassini: The total cost of this scientific exploration mission is about US$3.26billion, including $1.4billion for pre-launch development, $704 million for mission operations, $54million for tracking and $422million for the launch vehicle.

Picture: http://saturn.jpl.nasa.gov/photos/imagedetails/index.cfm?imageId=4497. Enceladus with saturn rings and titan in background31