Stardust mission

Panels of siUca aerogels have already been flown on several Space Shuttle missions (74). Currently a STARDUST mission has been planned by NASA to use aerogels to capture cometary samples (>1000 particles of >15 micron diameter) and interstellar dust particles... 

Stardust February 7, 1999, saw the start of NASA s Stardust mission the cometary probe, the first mission to collect cosmic dust and return the sample to Earth, has a time-of-flight mass spectrometer (CIDA, Cometary and Interstellar Dust Analyser) on board. This analyses the ions which are formed when cosmic dust particles hit the instrument s surface. In June 2004, the probe reached its goal, the comet 8 IPAVild 2, getting as close as 236 km The CIDA instrument, which was developed at the Max Planck Institute for Extraterrestrial Physics in Garching (near Munich), studied both cometary dust and interstellar star dust. 

It is reasonable to consider the assumption that life began, somehow, among one of the mixtures of small organic molecules that are produced by abiotic processes. The only natural examples in hand today are the components of meteorites that have fallen to Earth (see Section 5.2.1) and particles returned by the Stardust mission. Spectroscopy has also yielded partial lists of the organic molecules in interstellar space and interplanetary dust clouds. 

The Stardust mission succeeded in bringing solid particles from the Wild 2 comet to the Earth. Comets are the intriguing celestial bodies that are believed the last witnesses of the formation of the solar system. They are considered to be aggregates of primordial interstellar dust particles, the last reminders of protosolar nebula. Even simple spectroscopic observation indicates that comets are rich in simple organic species, which may undergo further photochemical transformations during their life within the solar system [35, 36], Hundreds of organic molecules... 

Sulfur is relatively undepleted by condensation into interstellar grains, so that its isotopic composition has been partly measured by radioastronomers, who detect emission lines from the molecule CS in the interstellar medium. By comparing rotational transition lines from 13C34S with those from 12C33S it has been found that the sulfur isotopic ratio in the interstellar gas is 34S/33S = 6.3 l, which is in reasonable agreement with the value 5.5 in the solar system. One will certainly hope to check this with measurements of S isotopes in interstellar grains that today drift into the solar system and that can be captured by NASA s STARDUST mission. 

Presolar grains are found in small quantities (with concentrations of ppb to several 100 ppm, see Table 2.1) in all types of primitive Solar System materials (Lodders Amari 2005 Zinner 2007). This includes primitive meteorites (the chondrites), IDPs, some of which might originate from comets, Antarctic micrometeorites (AMMs), and samples from comet Wild 2 collected by NASA s Stardust mission. Presolar grains are nanometer to micrometer in size. The isotopic compositions, chemistry, and mineralogy of individual grains with sizes >100 nm can be studied in the laboratory. Important analysis techniques are secondary ion mass spectrometry (SIMS) and resonance ionization mass spectrometry (RIMS)... 

With the success of the Stardust mission, tests of our models for solar nebula, and thus protoplanetary disk evolution, are no longer limited to asteroidal bodies (meteorites), but now can be applied to cometary bodies as well. Stardust returned dust grains that were ejected from the surface of comet Wild 2, a Jupiter-family cometthatis thought to have formed at distances of >20 AU from the Sun (Brownlee et al. 2006). Thus, we now have samples of materials from the outer solar nebula that can be studied in detail. 

Among the goals for the Stardust mission was identifying the origin of the crystalline silicates in comets, whose presence in comets had been known from observations of comets Halley and Hale-Bopp (as reviewed in Bockelee-Morvan... 

Figure 5.5 Winds in the solar nebula might be one of the possible processes responsible for the mixing of hot and cold components found in both meteorites and comets. Meteorites contain calcium-aluminum-rich inclusions (CAIs, formed at about 2000 K) and chondrules (formed at about 1650K), which may have been created near the proto-Sun and then blown (gray arrows) several astronomical units away, into the region of the asteroids between Mars and Jupiter, where they were embedded in a matrix of temperature-sensitive, carbon-based cold components. The hot component in comets, tiny grains of annealed silicate dust (olivine) is vaporized at about 1600 K, suggesting that it never reached the innermost region of the disk before it was transported (white arrows) out beyond the orbit of Pluto, where it was mixed with ices and some unheated silicate dust ( cold components). Vigorous convection in the accretion disk may have contributed to the transport of many materials and has been dramatically confirmed by the Stardust mission (Nuth 2001).

In order to consider the processes of dust coagulation in the early Solar System, we first review the characteristics of this material. Of considerable importance is the fact that these samples - represented principally by chondritic meteorites, but also by IDPs and by samples from Comet Wild 2 collected by the Stardust mission - all come from parent bodies of different kinds. As a result, even the most primitive of these materials has been processed, both physically and chemically, to different degrees. The processes that affected Solar System dust may have occurred in different environments such as the solar nebula (e.g. evaporation/condensation, annealing) and asteroidal parent bodies (aqueous alteration and/or thermal processing, mild compaction to extensive lithihcation). A major challenge is to understand the effects of this secondary processing. 

Fortunately, and perhaps surprisingly, the Universe provides a means to address these important questions. Today we are witnessing as the answers emerge to these age-old questions. We now know that asteroids and comets of the Solar System have preserved a detailed record of the dramatic events that four billion years ago gave birth to our planetary system in only a few million years. Gravity and radiation pressure conspire to deliver almost pristine samples of the early Solar System to Earth in the form of meteorites and interplanetary dust particles. We have also taken this process one step further with the successful return of particles from the coma of comet Wild 2 by NASA s Stardust mission. Detailed chemical and mineralogical analyses of these materials allow for the reconstruction of the history of our planetary system. 

Thus, it is necessary to consider the role of the dust in the ISM. Dust comprises about 1% ofthe mass ofthe material in the ISM and can act as a surface upon which chemistry can occur (Fig. 4). Although we have yet to actually examine a piece of interstellar dust we believe it is similar to that found in the Solar System and recently collected by the Stardust mission. The dust is either carbonaceous or silicate in nature, comprising of small particles, typically sub-microns in size, probably with an irregular (fractal ) structure. Being so cold (around 10 K) the dust grains act as a depository for any gaseous molecules which "stick" to the surface. Hence H atoms may collide with the surface, and subsequent reaction between such H ... 

Finally, let us recall the attempts to measure the 244Pu content in the local ISM, which may have some interesting astrophysical implications. At present, this can be done through the analysis of dust grains of identified interstellar origin recovered in deep-sea sediments (e.g. [52]). In a near future, the determination of elemental and isotopic composition of the ISM grains will be a major goal of research with their recovery to Earth by the Stardust mission [53],... 

Comets EUV spectroscopy in-situ dust collection (see also IDPs) Cl chondritic meteorites Ar abundance, upper limits for He, Ne. Stem 1999a. Stardust mission Lodders and Osborne 1999 Ehrenfreund et al. 2001. 

Comets are space snowballs with some dirt sprinkled in. No, really. Comets are typically balls of rock, frozen water, and gases. Sometimes other chemicals are present in much smedler amounts these include methanol and ethtmol, hydrocarbons, and in 2009 NASA s Stardust mission confirmed that glycine (an amino acid) was present in the comet Ccdled Wild 2. 

The Stardust Mission was designed around the fact that low-density aerogel had been demonstrated to be an excellent hypervelocity particle capture medium [17]. The mission plan was to transport a grid of aerogel cells into space, rendezvous with a comet, capture material from the comet in the aerogel, and return the collected samples to the earth [20]. The primary science requirement of the mission was that 1,000 cometary particles, 15 pm or larger in diameter, be captured and returned to Earth. 

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