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106-527: The Flats are about 12 miles (19 km) long and 5 miles (8 km) wide, with a crust almost 5 ft (1.5m) thick at the center and less than one inch (2.5 cm) towards the edges. It is estimated to hold 147 million tons of salt , approximately 90% of which is common table salt . Geologist Grove Karl Gilbert named the area after Benjamin Bonneville , a U.S. Army officer who explored the Intermountain West in

212-652: A radiation-hardened RAD6000 32-bit processor card. For storing data when the spacecraft was unable to communicate with Earth, the processor card was able to store 128  megabytes , 20% of which was occupied by the flight system software. The system software is a form of VxWorks , an embedded operating system developed by Wind River Systems . Comet and interstellar particles are collected in ultra low density aerogel . The tennis racket -sized collector tray contained ninety blocks of aerogel, providing more than 1,000 square centimeters of surface area to capture cometary and interstellar dust grains. To collect

318-452: A 15-watt transponder design originally intended for the Cassini spacecraft . The probe was powered by two solar arrays , providing an average of 330 watts of power. The arrays also included Whipple shields to protect the delicate surfaces from the potentially damaging cometary dust while the spacecraft was in the coma of Wild 2. The solar array design was derived primarily from

424-716: A Discovery-class mission in Denver, Colorado. JPL provided mission management for the NASA division for mission operations. The principal investigator of the mission was Dr. Donald Brownlee from the University of Washington. The spacecraft bus measured 1.7 meters (5 ft 7 in) in length, and 0.66 meters (2 ft 2 in) in width, a design adapted from the SpaceProbe deep space bus developed by Lockheed Martin Astronautics . The bus

530-403: A base. This is also true of some compounds with ionic character, typically oxides or hydroxides of less-electropositive metals (so the compound also has significant covalent character), such as zinc oxide , aluminium hydroxide , aluminium oxide and lead(II) oxide . Electrostatic forces between particles are strongest when the charges are high, and the distance between the nuclei of the ions

636-497: A human-made object. The capsule followed a drastic reentry profile, going from a velocity of Mach 36 to subsonic speed within 110 seconds. Peak deceleration was 34  g , encountered 40 seconds into the reentry at an altitude of 55 km over Spring Creek, Nevada . The phenolic-impregnated carbon ablator (PICA) heat shield , produced by Fiber Materials Inc., reached a temperature of more than 2,900 °C during this steep reentry. The capsule then parachuted to

742-508: A lack of aqueous processing of the cometary dust; limited pure carbon ( CHON ) was also found in the samples returned; methylamine and ethylamine was found in the aerogel but was not associated with specific particles. In 2010, Dr. Andrew Westphal announced that Stardust@home volunteer Bruce Hudson found a track (labeled "I1043,1,30") among the many images of the aerogel that may contain an interstellar dust grain. The program allows for any volunteer discoveries to be recognized and named by

848-597: A landing in Utah in the Bonneville Salt Flats . During the second encounter with Earth, the Sample Return Capsule was released on Jan 15, 2006. Immediately afterwards, Stardust was put into a "divert maneuver" to avoid entering the atmosphere alongside the capsule. Under twenty kilograms of propellant remained onboard after the maneuver. On 29 January 2006, the spacecraft was put in hibernation mode with only

954-589: A landing in the Bonneville Salt Flats after its flybys of asteroid 5535 Annefrank in 2002 and comet Wild 2 in 2004. Salt (chemistry) In chemistry , a salt or ionic compound is a chemical compound consisting of an assembly of positively charged ions ( cations ) and negatively charged ions ( anions ), which results in a compound with no net electric charge (electrically neutral). The constituent ions are held together by electrostatic forces termed ionic bonds . The component ions in

1060-415: A network with long-range crystalline order. Many other inorganic compounds were also found to have similar structural features. These compounds were soon described as being constituted of ions rather than neutral atoms , but proof of this hypothesis was not found until the mid-1920s, when X-ray reflection experiments (which detect the density of electrons), were performed. Principal contributors to

1166-453: A paste and then heated to a temperature where the ions in neighboring reactants can diffuse together during the time the reactant mixture remains in the oven. Other synthetic routes use a solid precursor with the correct stoichiometric ratio of non-volatile ions, which is heated to drive off other species. In some reactions between highly reactive metals (usually from Group 1 or Group 2 ) and highly electronegative halogen gases, or water,

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1272-507: A phase angle of 110 degrees. The AutoNav software was used during the flyby. During the flyby the spacecraft deployed the Sample Collection plate to collect dust grain samples from the coma , and took detailed pictures of the icy nucleus . On 19 March 2006, Stardust scientists announced that they were considering the possibility of redirecting the spacecraft on a secondary mission to image Comet Tempel 1 . The comet

1378-416: A potential energy well with minimum energy when the nuclei are separated by a specific equilibrium distance. If the electronic structure of the two interacting bodies is affected by the presence of one another, covalent interactions (non-ionic) also contribute to the overall energy of the compound formed. Salts are rarely purely ionic, i.e. held together only by electrostatic forces. The bonds between even

1484-456: A program titled, Stardust@home . In April 2014, NASA reported they had recovered seven particles of interstellar dust from the aerogel. Stardust was launched carrying two sets of identical pairs of square 10.16-centimeter (4 in) silicon wafers . Each pair featured engravings of well over one million names of people who participated in the public outreach program by filling out internet forms available in late 1997 and mid-1998. One pair of

1590-400: A reducing agent such as carbon) such that the metal ions gain electrons to become neutral atoms. According to the nomenclature recommended by IUPAC , salts are named according to their composition, not their structure. In the most simple case of a binary salt with no possible ambiguity about the charges and thus the stoichiometry , the common name is written using two words. The name of

1696-529: A role in determining the strength of the interactions and propensity to melt. Even when the local structure and bonding of an ionic solid is disrupted sufficiently to melt it, there are still strong long-range electrostatic forces of attraction holding the liquid together and preventing ions boiling to form a gas phase. This means that even room temperature ionic liquids have low vapour pressures, and require substantially higher temperatures to boil. Boiling points exhibit similar trends to melting points in terms of

1802-503: A salt can be either inorganic , such as chloride (Cl ), or organic , such as acetate ( CH 3 COO ). Each ion can be either monatomic (termed simple ion ), such as sodium (Na ) and chloride (Cl ) in sodium chloride , or polyatomic , such as ammonium ( NH 4 ) and carbonate ( CO 3 ) ions in ammonium carbonate . Salts containing basic ions hydroxide (OH ) or oxide (O ) are classified as bases , for example sodium hydroxide . Individual ions within

1908-460: A salt usually have multiple near neighbours, so they are not considered to be part of molecules, but instead part of a continuous three-dimensional network. Salts usually form crystalline structures when solid. Salts composed of small ions typically have high melting and boiling points , and are hard and brittle . As solids they are almost always electrically insulating , but when melted or dissolved they become highly conductive , because

2014-498: A shorter wavelength when they are involved in more covalent interactions. This occurs during hydration of metal ions, so colorless anhydrous salts with an anion absorbing in the infrared can become colorful in solution. Salts exist in many different colors , which arise either from their constituent anions, cations or solvates . For example: Some minerals are salts, some of which are soluble in water. Similarly, inorganic pigments tend not to be salts, because insolubility

2120-407: A target, and so the vast flat plane of the flats serves as an ideal location to measure the linear distance traveled by arrows without geographic interference. Both the 1977 (archer Don Brown) and 1982 (archer Alan Webster) world records were set there; while the current world record, achieved in 1987 (archer Don Brown), was set at the salt flats near Smith Creek, Nevada . The thickness of salt crust

2226-527: A variety of structures are commonly observed, and theoretically rationalized by Pauling's rules . In some cases, the anions take on a simple cubic packing and the resulting common structures observed are: Some ionic liquids , particularly with mixtures of anions or cations, can be cooled rapidly enough that there is not enough time for crystal nucleation to occur, so an ionic glass is formed (with no long-range order). Within any crystal, there will usually be some defects. To maintain electroneutrality of

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2332-626: A wide variety of uses and applications. Many minerals are ionic. Humans have processed common salt (sodium chloride) for over 8000 years, using it first as a food seasoning and preservative, and now also in manufacturing, agriculture , water conditioning, for de-icing roads, and many other uses. Many salts are so widely used in society that they go by common names unrelated to their chemical identity. Examples of this include borax , calomel , milk of magnesia , muriatic acid , oil of vitriol , saltpeter , and slaked lime . Soluble salts can easily be dissolved to provide electrolyte solutions. This

2438-483: Is K). When one of the ions already has a multiplicative prefix within its name, the alternate multiplicative prefixes ( bis- , tris- , tetrakis- , ...) are used. For example, Ba(BrF 4 ) 2 is named barium bis(tetrafluoridobromate) . Compounds containing one or more elements which can exist in a variety of charge/ oxidation states will have a stoichiometry that depends on which oxidation states are present, to ensure overall neutrality. This can be indicated in

2544-412: Is a critical factor in racing use of the salt flats. The Bureau of Land Management (BLM) has undertaken multiple studies on the topic; while a 2007 study determined that there was little change in the crust's thickness from 1988 to 2003, more recent studies have shown a reduction in thickness, especially in the northwest area where racing occurs. The flats' overall area has contracted significantly over

2650-407: Is a simple way to control the concentration and ionic strength . The concentration of solutes affects many colligative properties , including increasing the osmotic pressure , and causing freezing-point depression and boiling-point elevation . Because the solutes are charged ions they also increase the electrical conductivity of the solution. The increased ionic strength reduces the thickness of

2756-400: Is highest in polar solvents (such as water ) or ionic liquids , but tends to be low in nonpolar solvents (such as petrol / gasoline ). This contrast is principally because the resulting ion–dipole interactions are significantly stronger than ion-induced dipole interactions, so the heat of solution is higher. When the oppositely charged ions in the solid ionic lattice are surrounded by

2862-528: Is named iron(2+) sulfate (with the 2+ charge on the Fe ions balancing the 2− charge on the sulfate ion), whereas Fe 2 (SO 4 ) 3 is named iron(3+) sulfate (because the two iron ions in each formula unit each have a charge of 3+, to balance the 2− on each of the three sulfate ions). Stock nomenclature , still in common use, writes the oxidation number in Roman numerals (... , −II, −I, 0, I, II, ...). So

2968-548: Is required for fastness. Some organic dyes are salts, but they are virtually insoluble in water. Salts can elicit all five basic tastes , e.g., salty ( sodium chloride ), sweet ( lead diacetate , which will cause lead poisoning if ingested), sour ( potassium bitartrate ), bitter ( magnesium sulfate ), and umami or savory ( monosodium glutamate ). Salts of strong acids and strong bases (" strong salts ") are non- volatile and often odorless, whereas salts of either weak acids or weak bases (" weak salts ") may smell like

3074-414: Is small. In such cases, the compounds generally have very high melting and boiling points and a low vapour pressure . Trends in melting points can be even better explained when the structure and ionic size ratio is taken into account. Above their melting point, salts melt and become molten salts (although some salts such as aluminium chloride and iron(III) chloride show molecule-like structures in

3180-551: Is the formation of an F-center , a free electron occupying an anion vacancy. When the compound has three or more ionic components, even more defect types are possible. All of these point defects can be generated via thermal vibrations and have an equilibrium concentration. Because they are energetically costly but entropically beneficial, they occur in greater concentration at higher temperatures. Once generated, these pairs of defects can diffuse mostly independently of one another, by hopping between lattice sites. This defect mobility

3286-421: Is the source of most transport phenomena within an ionic crystal, including diffusion and solid state ionic conductivity . When vacancies collide with interstitials (Frenkel), they can recombine and annihilate one another. Similarly, vacancies are removed when they reach the surface of the crystal (Schottky). Defects in the crystal structure generally expand the lattice parameters , reducing the overall density of

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3392-411: Is the summation of the interaction of all sites with all other sites. For unpolarizable spherical ions, only the charges and distances are required to determine the electrostatic interaction energy. For any particular ideal crystal structure, all distances are geometrically related to the smallest internuclear distance. So for each possible crystal structure, the total electrostatic energy can be related to

3498-476: The Kapustinskii equation . Using an even simpler approximation of the ions as impenetrable hard spheres, the arrangement of anions in these systems are often related to close-packed arrangements of spheres, with the cations occupying tetrahedral or octahedral interstices . Depending on the stoichiometry of the salt, and the coordination (principally determined by the radius ratio ) of cations and anions,

3604-515: The Kuiper belt . In 2009 it was announced by NASA that scientists had identified one of the fundamental chemical building blocks of life in a comet for the first time: glycine , an amino acid, was detected in the material ejected from Comet Wild 2 in 2004 and captured by the Stardust probe. Glycine has been detected in meteorites before and there are also observations in interstellar gas clouds, but

3710-525: The Stardust Sample Collection tray, which was brought back to Earth for analysis. The spacecraft was three-axis stabilized with eight 4.41  N hydrazine monopropellant thrusters , and eight 1 N thrusters to maintain attitude control (orientation); necessary minor propulsion maneuvers were performed by these thrusters as well. The spacecraft was launched with 80 kilograms of propellant. Information for spacecraft positioning

3816-453: The Stardust capsule returned to Earth in 2006. Beginning in the 1980s, scientists began seeking a dedicated mission to study a comet. During the early 1990s, several missions to study Comet Halley became the first successful missions to return close-up data. However, the US cometary mission, Comet Rendezvous Asteroid Flyby , was canceled for budgetary reasons. In the mid-1990s, further support

3922-525: The Stardust find is described as a first in cometary material. Isotope analysis indicates that the Late Heavy Bombardment included cometary impacts after the Earth coalesced but before life evolved. Carl Pilcher, who leads NASA's Astrobiology Institute commented that "The discovery of glycine in a comet supports the idea that the fundamental building blocks of life are prevalent in space, and strengthens

4028-416: The anhydrous material. Molten salts will solidify on cooling to below their freezing point . This is sometimes used for the solid-state synthesis of complex salts from solid reactants, which are first melted together. In other cases, the solid reactants do not need to be melted, but instead can react through a solid-state reaction route . In this method, the reactants are repeatedly finely ground into

4134-405: The conjugate acid (e.g., acetates like acetic acid ( vinegar ) and cyanides like hydrogen cyanide ( almonds )) or the conjugate base (e.g., ammonium salts like ammonia ) of the component ions. That slow, partial decomposition is usually accelerated by the presence of water, since hydrolysis is the other half of the reversible reaction equation of formation of weak salts. Salts have long had

4240-580: The electrical double layer around colloidal particles, and therefore the stability of emulsions and suspensions . The chemical identity of the ions added is also important in many uses. For example, fluoride containing compounds are dissolved to supply fluoride ions for water fluoridation . Solid salts have long been used as paint pigments, and are resistant to organic solvents, but are sensitive to acidity or basicity. Since 1801 pyrotechnicians have described and widely used metal-containing salts as sources of colour in fireworks. Under intense heat,

4346-435: The electronegative halogens gases to salts. Salts form upon evaporation of their solutions . Once the solution is supersaturated and the solid compound nucleates. This process occurs widely in nature and is the means of formation of the evaporite minerals. Insoluble salts can be precipitated by mixing two solutions, one with the cation and one with the anion in it. Because all solutions are electrically neutral,

Bonneville Salt Flats - Misplaced Pages Continue

4452-617: The "World Finals" take place early October. These three events welcome cars, trucks, and motorcycles. The "Bub Motorcycle Speed Trials" are for motorcycles only. World records are contested at the Mike Cook ShootOut in September. The Southern California Timing Association and the Utah Salt Flats Racing Association organizes and plans the multi-vehicle events, but all event promoters contribute to prepping and maintaining

4558-727: The 1830s. In 1907, Bill Rishel and two local businessmen tested the suitability of the salt for driving by taking a Pierce-Arrow onto its surface. A railway line across the Flats was completed in 1910, marking the first permanent crossing. The first land speed record was set there in 1914 by Teddy Tetzlaff . Entertainment filmed at the Flats include portions of Walking with Dinosaurs Special - The Ballad of Big Al , Knight Rider , Warlock , Independence Day (1996) and its sequel , SLC Punk , Cremaster 2 from Cremaster Cycle , The Brown Bunny , The World's Fastest Indian , Gerry , The Tree of Life , Top Gear and Pirates of

4664-569: The Bonneville Salt Flats. The record for wheel-driven vehicles (449 MPH) was set there in 2018, and for rocket or jet propelled vehicles (630 MPH; since superseded) in 1970. Motorcar racing has taken place at the salt flats since 1914. Racing takes place at part of the Bonneville Salt Flats known as the Bonneville Speedway . There are five major land speed events that take place at the Bonneville Salt Flats. Bonneville "Speed Week" takes place mid-August followed by "World of Speed" in September and

4770-735: The Caribbean: At World's End . Furthermore, the Pontiac Bonneville (former flagship sedan of the Pontiac motor division), the Triumph Bonneville motorcycle, and the Bonneville International media company are all named for the Flats. The Bonneville Salt Flats hosts the annual US Flight Archery Championships. The goal of flight archery is to shoot arrows from bows at the greatest distance possible without regard to hitting

4876-540: The Small Spacecraft Technology Initiative (SSTI) spacecraft development guidelines. The arrays provided a unique method of switching strings from series to parallel depending on the distance from the Sun. A single nickel–hydrogen ( NiH 2 ) battery was also included to provide the spacecraft with power when the solar arrays received too little sunlight. The computer on the spacecraft operated using

4982-658: The anion and cation. This difference in electronegativities means that the charge separation, and resulting dipole moment, is maintained even when the ions are in contact (the excess electrons on the anions are not transferred or polarized to neutralize the cations). Although chemists classify idealized bond types as being ionic or covalent, the existence of additional types such as hydrogen bonds and metallic bonds , for example, has led some philosophers of science to suggest that alternative approaches to understanding bonding are required. This could be by applying quantum mechanics to calculate binding energies. The lattice energy

5088-507: The anions and net positive charge of the cations. There is also a small additional attractive force from van der Waals interactions which contributes only around 1–2% of the cohesive energy for small ions. When a pair of ions comes close enough for their outer electron shells (most simple ions have closed shells ) to overlap, a short-ranged repulsive force occurs, due to the Pauli exclusion principle . The balance between these forces leads to

5194-462: The atoms can be ionized by electron transfer , a process thermodynamically understood using the Born–Haber cycle . Salts are formed by salt-forming reactions Ions in salts are primarily held together by the electrostatic forces between the charge distribution of these bodies, and in particular, the ionic bond resulting from the long-ranged Coulomb attraction between the net negative charge of

5300-590: The cation (the unmodified element name for monatomic cations) comes first, followed by the name of the anion. For example, MgCl 2 is named magnesium chloride , and Na 2 SO 4 is named sodium sulfate ( SO 4 , sulfate , is an example of a polyatomic ion ). To obtain the empirical formula from these names, the stoichiometry can be deduced from the charges on the ions, and the requirement of overall charge neutrality. If there are multiple different cations and/or anions, multiplicative prefixes ( di- , tri- , tetra- , ...) are often required to indicate

5406-558: The compound is the result of a reaction between a strong acid and a weak base , the result is an acid salt . If it is the result of a reaction between a strong base and a weak acid , the result is a base salt . If it is the result of a reaction between a strong acid and a strong base, the result is a neutral salt. Weak acids reacted with weak bases can produce ionic compounds with both the conjugate base ion and conjugate acid ion, such as ammonium acetate . Some ions are classed as amphoteric , being able to react with either an acid or

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5512-462: The constituent ions, or the hydrated form of the same compound. The anions in compounds with bonds with the most ionic character tend to be colorless (with an absorption band in the ultraviolet part of the spectrum). In compounds with less ionic character, their color deepens through yellow, orange, red, and black (as the absorption band shifts to longer wavelengths into the visible spectrum). The absorption band of simple cations shifts toward

5618-406: The counterions can be chosen to ensure that even when combined into a single solution they will remain soluble as spectator ions . If the solvent is water in either the evaporation or precipitation method of formation, in many cases the ionic crystal formed also includes water of crystallization , so the product is known as a hydrate , and can have very different chemical properties compared to

5724-861: The crystal. Defects also result in ions in distinctly different local environments, which causes them to experience a different crystal-field symmetry , especially in the case of different cations exchanging lattice sites. This results in a different splitting of d-electron orbitals , so that the optical absorption (and hence colour) can change with defect concentration. Ionic compounds containing hydrogen ions (H ) are classified as acids , and those containing electropositive cations and basic anions ions hydroxide (OH ) or oxide (O ) are classified as bases . Other ionic compounds are known as salts and can be formed by acid–base reactions . Salts that produce hydroxide ions when dissolved in water are called alkali salts , and salts that produce hydrogen ions when dissolved in water are called acid salts . If

5830-464: The crystals, defects that involve loss of a cation will be associated with loss of an anion, i.e. these defects come in pairs. Frenkel defects consist of a cation vacancy paired with a cation interstitial and can be generated anywhere in the bulk of the crystal, occurring most commonly in compounds with a low coordination number and cations that are much smaller than the anions. Schottky defects consist of one vacancy of each type, and are generated at

5936-478: The development of a theoretical treatment of ionic crystal structures were Max Born , Fritz Haber , Alfred Landé , Erwin Madelung , Paul Peter Ewald , and Kazimierz Fajans . Born predicted crystal energies based on the assumption of ionic constituents, which showed good correspondence to thermochemical measurements, further supporting the assumption. Many metals such as the alkali metals react directly with

6042-521: The electrons in the metal ions or small molecules can be excited. These electrons later return to lower energy states, and release light with a colour spectrum characteristic of the species present. In chemical synthesis , salts are often used as precursors for high-temperature solid-state synthesis. Many metals are geologically most abundant as salts within ores . To obtain the elemental materials, these ores are processed by smelting or electrolysis , in which redox reactions occur (often with

6148-564: The electrostatic energy of unit charges at the nearest neighboring distance by a multiplicative constant called the Madelung constant that can be efficiently computed using an Ewald sum . When a reasonable form is assumed for the additional repulsive energy, the total lattice energy can be modelled using the Born–Landé equation , the Born–Mayer equation , or in the absence of structural information,

6254-417: The encounter with Comet Wild 2 in 2003. At 19:21:28 UTC, on 2 January 2004, Stardust encountered Comet Wild  2 on the sunward side with a relative velocity of 6.1 km/s at a distance of 237 km (147 mi). The original encounter distance was planned to be 150 km (93 mi), but this was changed after a safety review board increased the closest approach distance to minimize

6360-413: The end of the useful life for the spacecraft. At 04:50:20 UTC on 2 November 2002, Stardust encountered asteroid 5535 Annefrank from a distance of 3,079 km (1,913 mi). The solar phase angle ranged from 130 degrees to 47 degrees during the period of observations. This encounter was used primarily as an engineering test of the spacecraft and ground operations in preparation for

6466-425: The establishment of NASA. The return capsule is displayed in sample collection mode, alongside a sample of the aerogel used to collect samples. The comet samples show that the outer regions of the early Solar System were not isolated and were not a refuge where interstellar materials could commonly survive. The data suggest that high-temperature inner Solar System material formed and was subsequently transferred to

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6572-498: The examples given above would be named iron(II) sulfate and iron(III) sulfate respectively. For simple ions the ionic charge and the oxidation number are identical, but for polyatomic ions they often differ. For example, the uranyl(2+) ion, UO 2 , has uranium in an oxidation state of +6, so would be called a dioxouranium(VI) ion in Stock nomenclature. An even older naming system for metal cations, also still widely used, appended

6678-557: The findings are: a wide range of organic compounds , including two that contain biologically usable nitrogen ; indigenous aliphatic hydrocarbons with longer chain lengths than those observed in the diffuse interstellar medium ; abundant amorphous silicates in addition to crystalline silicates such as olivine and pyroxene , proving consistency with the mixing of Solar System and interstellar matter, previously deduced spectroscopically from ground observations; hydrous silicates and carbonate minerals were found to be absent, suggesting

6784-470: The first look at the changes to a comet nucleus produced after a close approach to the Sun. NExT also would extend the mapping of Tempel 1, making it the most mapped comet nucleus to date. This mapping would help address the major questions of comet nucleus geology. The flyby mission was expected to consume almost all of the remaining fuel, signaling the end of the operability of the spacecraft. The AutoNav software (for autonomous navigation) would control

6890-400: The grain. The aerogel was packed in an aluminium grid and fitted into a Sample Return Capsule (SRC), which was to be released from the spacecraft as it passed Earth in 2006. To analyze the aerogel for interstellar dust, one million photographs will be needed to image the entirety of the sampled grains. The images will be distributed to home computer users to aid in the study of the data using

6996-653: The ground, finally landing at 10:12 UTC at the Utah Test and Training Range , near the U.S. Army Dugway Proving Ground . The capsule was then transported by military aircraft from Utah to Ellington Air Force Base in Houston , Texas , then transferred by road in an unannounced convoy to the Planetary Materials Curatorial facility at Johnson Space Center in Houston to begin analysis. The sample container

7102-445: The ions become completely mobile. For this reason, molten salts and solutions containing dissolved salts (e.g., sodium chloride in water) can be used as electrolytes . This conductivity gain upon dissolving or melting is sometimes used as a defining characteristic of salts. In some unusual salts: fast-ion conductors , and ionic glasses , one or more of the ionic components has a significant mobility, allowing conductivity even while

7208-469: The ions become mobile. Some salts have large cations, large anions, or both. In terms of their properties, such species often are more similar to organic compounds. In 1913 the structure of sodium chloride was determined by William Henry Bragg and William Lawrence Bragg . This revealed that there were six equidistant nearest-neighbours for each atom, demonstrating that the constituents were not arranged in molecules or finite aggregates, but instead as

7314-446: The liquid phase). Inorganic compounds with simple ions typically have small ions, and thus have high melting points, so are solids at room temperature. Some substances with larger ions, however, have a melting point below or near room temperature (often defined as up to 100 °C), and are termed ionic liquids . Ions in ionic liquids often have uneven charge distributions, or bulky substituents like hydrocarbon chains, which also play

7420-399: The material as a whole remains solid. This is often highly temperature dependent, and may be the result of either a phase change or a high defect concentration. These materials are used in all solid-state supercapacitors , batteries , and fuel cells , and in various kinds of chemical sensors . The colour of a salt is often different from the colour of an aqueous solution containing

7526-614: The microchips was positioned on the spacecraft and the other was attached to the sample return capsule. Stardust was launched at 21:04:15 UTC on 7 February 1999, by the National Aeronautics and Space Administration from Space Launch Complex 17A at the Cape Canaveral Air Force Station in Florida, aboard a Delta II 7426 launch vehicle. The complete burn sequence lasted for 27 minutes bringing

7632-427: The most electronegative / electropositive pairs such as those in caesium fluoride exhibit a small degree of covalency . Conversely, covalent bonds between unlike atoms often exhibit some charge separation and can be considered to have a partial ionic character. The circumstances under which a compound will have ionic or covalent character can typically be understood using Fajans' rules , which use only charges and

7738-440: The name by specifying either the oxidation state of the elements present, or the charge on the ions. Because of the risk of ambiguity in allocating oxidation states, IUPAC prefers direct indication of the ionic charge numbers. These are written as an arabic integer followed by the sign (... , 2−, 1−, 1+, 2+, ...) in parentheses directly after the name of the cation (without a space separating them). For example, FeSO 4

7844-467: The opposite pole of a polar molecule, the solid ions are pulled out of the lattice and into the liquid. If the solvation energy exceeds the lattice energy , the negative net enthalpy change of solution provides a thermodynamic drive to remove ions from their positions in the crystal and dissolve in the liquid. In addition, the entropy change of solution is usually positive for most solid solutes like salts, which means that their solubility increases when

7950-453: The orbit of Wild 2 was affected by the gravitational pull of Jupiter , moving the orbit inward, closer to the Sun. In planning the mission, it was expected that most of the original material from which the comet formed would still be preserved. The primary science objectives of the mission included: The spacecraft was designed, built and operated by Lockheed Martin Astronautics as

8056-408: The particles without damaging them, a silicon -based solid with a porous, sponge -like structure is used in which 99.8 percent of the volume is empty space. Aerogel has 1 ⁄ 1000  the density of glass , another silicon-based solid to which it may be compared. When a particle hits the aerogel, it becomes buried in the material, creating a long track, up to 200 times the length of

8162-628: The past several decades. The cause or causes of this remain unclear, but many believe adjacent evaporative potash mining is the primary factor. Collaboration between racing organizations, the potash mine, and the BLM led to a pilot program begun in 1998 to release excess brine onto the salt flats during winter. Plans to increase the volume of brine returned to the salt flats are hoped to halt loss of crust thickness, or possibly restore it where it has become too thin to sustain human use. Land speed records and Land speed racing records have been set many times on

8268-473: The potential for catastrophic dust collisions. The relative velocity between the comet and the spacecraft was such that the comet actually overtook the spacecraft from behind as they traveled around the Sun. During the encounter, the spacecraft was on the Sunlit side of the nucleus, approaching at a solar phase angle of 70 degrees, reaching a minimum angle of 3 degrees near closest approach and departing at

8374-562: The recovery of particles of interstellar dust from the Discovery program's Stardust mission was announced. The Stardust samples are currently available for everyone to identify after completing the training at Berkeley webpage. The return capsule is currently located at the National Air and Space Museum in Washington, D.C. It began exhibition there on 1 October 2008, the 50th anniversary of

8480-407: The relative compositions, and cations then anions are listed in alphabetical order. For example, KMgCl 3 is named magnesium potassium trichloride to distinguish it from K 2 MgCl 4 , magnesium dipotassium tetrachloride (note that in both the empirical formula and the written name, the cations appear in alphabetical order, but the order varies between them because the symbol for potassium

8586-538: The salt. "Speed Week" events in August were canceled in 2015 and 2022, due to the poor condition of the salt in certain parts of the flats. The salt flats had been swamped by heavy rains earlier in the year, as usual, but this year the rains also triggered mudslides from surrounding mountains onto a section of the flats used for the land-speed racing courses. In 2004, the Stardust spacecraft released its sample-return capsule for

8692-422: The sample collector, which resided on the back side of the cometary dust collector. Dust grains are being observed and analyzed by a volunteer team through the citizen science project, Stardust@Home . The combined mass of the harvested sample was approximately 1 mg. In December 2006, seven papers were published in the scientific journal Science , discussing initial details of the sample analysis. Among

8798-448: The size of ions and strength of other interactions. When vapourized, the ions are still not freed of one another. For example, in the vapour phase sodium chloride exists as diatomic "molecules". Most salts are very brittle . Once they reach the limit of their strength, they cannot deform malleably , because the strict alignment of positive and negative ions must be maintained. Instead the material undergoes fracture via cleavage . As

8904-418: The sizes of each ion. According to these rules, compounds with the most ionic character will have large positive ions with a low charge, bonded to a small negative ion with a high charge. More generally HSAB theory can be applied, whereby the compounds with the most ionic character are those consisting of hard acids and hard bases: small, highly charged ions with a high difference in electronegativities between

9010-420: The sodium chloride structure (coordination number 6), and less again than those with a coordination number of 4. When simple salts dissolve , they dissociate into individual ions, which are solvated and dispersed throughout the resulting solution. Salts do not exist in solution. In contrast, molecular compounds, which includes most organic compounds, remain intact in solution. The solubility of salts

9116-407: The solar panels and receiver active, in a 3-year heliocentric orbit that would return it to Earth vicinity on 14 January 2009. A subsequent mission extension was approved on 3 July 2007, to bring the spacecraft back to full operation for a flyby of Comet Tempel 1 in 2011. The mission extension was the first to revisit a small Solar System body and used the remaining propellant, signaling

9222-790: The solvent, so certain patterns become apparent. For example, salts of sodium , potassium and ammonium are usually soluble in water. Notable exceptions include ammonium hexachloroplatinate and potassium cobaltinitrite . Most nitrates and many sulfates are water-soluble. Exceptions include barium sulfate , calcium sulfate (sparingly soluble), and lead(II) sulfate , where the 2+/2− pairing leads to high lattice energies. For similar reasons, most metal carbonates are not soluble in water. Some soluble carbonate salts are: sodium carbonate , potassium carbonate and ammonium carbonate . Salts are characteristically insulators . Although they contain charged atoms or clusters, these materials do not typically conduct electricity to any significant extent when

9328-437: The spacecraft for the 30 minutes prior to encounter. The mission objectives included the following: At 04:39:10 UTC on 15 February 2011, Stardust-NExT encountered Tempel 1 from a distance of 181 km (112 mi). An estimated 72 images were acquired during the encounter. These showed changes in the terrain and revealed portions of the comet never seen by Deep Impact . The impact site from Deep Impact

9434-464: The spacecraft into a heliocentric orbit that would bring the spacecraft around the Sun and past Earth for a gravity assist maneuver in 2001, to reach asteroid 5535 Annefrank in 2002 and Comet Wild 2 in 2004 at a low flyby velocity of 6.1 km/s. In 2004, the spacecraft performed a course correction that would allow it to pass by Earth a second time in 2006, to release the Sample Return Capsule for

9540-403: The substance is solid. In order to conduct, the charged particles must be mobile rather than stationary in a crystal lattice . This is achieved to some degree at high temperatures when the defect concentration increases the ionic mobility and solid state ionic conductivity is observed. When the salts are dissolved in a liquid or are melted into a liquid , they can conduct electricity because

9646-526: The suffixes -ous and -ic to the Latin root of the name, to give special names for the low and high oxidation states. For example, this scheme uses "ferrous" and "ferric", for iron(II) and iron(III) respectively, so the examples given above were classically named ferrous sulfate and ferric sulfate . Common salt-forming cations include: Common salt-forming anions (parent acids in parentheses where available) include: Stardust (spacecraft) Stardust

9752-422: The surfaces of a crystal, occurring most commonly in compounds with a high coordination number and when the anions and cations are of similar size. If the cations have multiple possible oxidation states , then it is possible for cation vacancies to compensate for electron deficiencies on cation sites with higher oxidation numbers, resulting in a non-stoichiometric compound . Another non-stoichiometric possibility

9858-399: The temperature increases. There are some unusual salts such as cerium(III) sulfate , where this entropy change is negative, due to extra order induced in the water upon solution, and the solubility decreases with temperature. The lattice energy , the cohesive forces between these ions within a solid, determines the solubility. The solubility is dependent on how well each ion interacts with

9964-413: The temperature is elevated (usually close to the melting point) a ductile–brittle transition occurs, and plastic flow becomes possible by the motion of dislocations . The compressibility of a salt is strongly determined by its structure, and in particular the coordination number . For example, halides with the caesium chloride structure (coordination number 8) are less compressible than those with

10070-413: The two solutions mixed must also contain counterions of the opposite charges. To ensure that these do not contaminate the precipitated salt, it is important to ensure they do not also precipitate. If the two solutions have hydrogen ions and hydroxide ions as the counterions, they will react with one another in what is called an acid–base reaction or a neutralization reaction to form water. Alternately

10176-515: The volunteer. Hudson named his discovery "Orion". In April 2011, scientists from the University of Arizona discovered evidence for the presence of liquid water in Comet Wild 2 . They have found iron and copper sulfide minerals that must have formed in the presence of water. The discovery shatters the existing paradigm that comets never get warm enough to melt their icy bulk. In the spring of 2014,

10282-413: Was a 385-kilogram robotic space probe launched by NASA on 7 February 1999. Its primary mission was to collect dust samples from the coma of comet Wild 2 , as well as samples of cosmic dust , and return them to Earth for analysis. It was the first sample return mission of its kind. En route to Comet Wild 2, it also flew by and studied the asteroid 5535 Annefrank . The primary mission

10388-442: Was also observed, though it was barely visible due to material settling back into the crater. On 24 March 2011 at approximately 23:00 UTC, Stardust conducted a burn to consume its remaining fuel. The spacecraft had little fuel left and scientists hoped the data collected would help in the development of a more accurate system for estimating fuel levels on spacecraft. After the data had been collected, no further antenna aiming

10494-440: Was given to a cheaper, Discovery-class mission that would study Comet Wild 2 in 2004. Stardust was competitively selected in the fall of 1995 as a NASA Discovery Program mission of low-cost with highly focused science goals. Construction of Stardust began in 1996, and was subject to the maximum contamination restriction, level 5 planetary protection . However, the risk of interplanetary contamination by alien life

10600-404: Was judged low, as particle impacts at over 450 metres per second (1,000 mph), even into aerogel , were believed to be terminal for any known microorganism. Comet Wild 2 was selected as the primary target of the mission for the rare chance to observe a long-period comet that has ventured close to the Sun . The comet has since become a short period comet after an event in 1974, where

10706-447: Was possible and the transmitter was switched off. The spacecraft sent an acknowledgement from approximately 312 million km (194 million mi) away in space. On 15 January 2006, at 05:57 UTC, the Sample Return Capsule successfully separated from Stardust . The SRC re-entered the Earth's atmosphere at 09:57 UTC, with a velocity of 12.9 km/s, the fastest reentry speed into Earth's atmosphere ever achieved by

10812-490: Was previously the target of the Deep ;Impact mission in 2005, sending an impactor into the surface. The possibility of this extension could be vital for gathering images of the impact crater which Deep Impact was unsuccessful in capturing due to dust from the impact obscuring the surface. On 3 July 2007 the mission extension was approved and renamed New Exploration of Tempel 1 (NExT). This investigation would provide

10918-570: Was primarily constructed with graphite fiber panels with an aluminum honeycomb support structure underneath; the entire spacecraft was covered with polycyanate, Kapton sheeting for further protection. To maintain low costs, the spacecraft incorporated many designs and technologies used in past missions or previously developed for future missions by the Small Spacecraft Technologies Initiative (SSTI). The spacecraft featured five scientific instruments to collect data, including

11024-581: Was provided by a star camera using FSW to determine attitude (Stellar Compass), an inertial measurement unit , and two Sun sensors . The Stellar Compass software was provided by Intelligent Decisions, Inc. For communicating with the Deep Space Network , the spacecraft transmitted data across the X-band using a 0.6-meter (2 ft 0 in) parabolic high-gain antenna , medium-gain antenna (MGA) and low-gain antennas (LGA) depending on mission phase, and

11130-543: Was successfully completed on 15 January 2006 when the sample return capsule returned to Earth. A mission extension, codenamed NExT , culminated in February 2011 with Stardust intercepting Comet Tempel 1 , a small Solar System body previously visited by Deep Impact in 2005. Stardust ceased operations in March 2011. On 14 August 2014, scientists announced the identification of possible interstellar dust particles from

11236-512: Was taken to a clean room with a cleanliness factor 100 times that of a hospital operating room to ensure the interstellar and comet dust was not contaminated. Preliminary estimations suggested at least a million  microscopic specks of dust were embedded in the aerogel collector. Ten particles were found to be at least 100  micrometers (0.1 mm) and the largest approximately 1,000 micrometers (1 mm). An estimated 45  interstellar dust impacts were also found on

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