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All sourcesNASA NTRSDOE OSTI
DOE OSTI2020

Materials Data on ZrN2 by Materials Project

ZrN2 is Fluorite structured and crystallizes in the tetragonal P4/nmm space group. The structure is three-dimensional. Zr4+ is bonded in a body-centered cubic geometry to eight N2- atoms. All Zr–N bond lengths are 2.28 Å. There are two inequivalent N2- sites. In the first N2- site, N2- is bonded to four equivalent Zr4+ atoms to form a mixture of edge and corner-sharing NZr4 tetrahedra. In the second N2- site, N2- is bonded to four equivalent Zr4+ atoms to form a mixture of distorted edge and corner-sharing NZr4 tetrahedra.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on UC3NO8 by Materials Project

UC3NO8 crystallizes in the monoclinic P2_1/c space group. The structure is two-dimensional and consists of two UC3NO8 sheets oriented in the (0, 1, 0) direction. U6+ is bonded in a 5-coordinate geometry to five O2- atoms. There are a spread of U–O bond distances ranging from 1.79–2.36 Å. There are three inequivalent C4+ sites. In the first C4+ site, C4+ is bonded in a bent 120 degrees geometry to two O2- atoms. There is one shorter (1.26 Å) and one longer (1.27 Å) C–O bond length. In the second C4+ site, C4+ is bonded in a bent 120 degrees geometry to two O2- atoms. There is one shorter (1.22 Å) and one longer (1.31 Å) C–O bond length. In the third C4+ site, C4+ is bonded in a linear geometry to two O2- atoms. There is one shorter (1.17 Å) and one longer (1.18 Å) C–O bond length. N2- is bonded in a 5-coordinate geometry to five O2- atoms. There are a spread of N–O bond distances ranging from 2.91–3.28 Å. There are eight inequivalent O2- sites. In the first O2- site, O2- is bonded in a single-bond geometry to one C4+ and one N2- atom. In the second O2- site, O2- is bonded in a distorted bent 150 degrees geometry to one U6+ and one C4+ atom. In the third O2- site, O2- is bonded in a distorted bent 120 degrees geometry to one U6+, one C4+, and one N2- atom. In the fourth O2- site, O2- is bonded in a single-bond geometry to one C4+ and one N2- atom. In the fifth O2- site, O2- is bonded in a distorted single-bond geometry to one U6+ and one C4+ atom. In the sixth O2- site, O2- is bonded in a single-bond geometry to one U6+ and one N2- atom. In the seventh O2- site, O2- is bonded in a single-bond geometry to one U6+ atom. In the eighth O2- site, O2- is bonded in a single-bond geometry to one C4+ and one N2- atom.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on CuC3N2O5 by Materials Project

NNCuCO(CO2)2 crystallizes in the triclinic P-1 space group. The structure is zero-dimensional and consists of four carbon dioxide molecules and two NNCuCO clusters. In each NNCuCO cluster, Cu2+ is bonded in a distorted single-bond geometry to one O2- atom. The Cu–O bond length is 2.02 Å. C4+ is bonded in a 1-coordinate geometry to two N2- and one O2- atom. Both C–N bond lengths are 1.36 Å. The C–O bond length is 1.23 Å. There are two inequivalent N2- sites. In the first N2- site, N2- is bonded in a distorted single-bond geometry to one C4+ atom. In the second N2- site, N2- is bonded in a 1-coordinate geometry to one C4+ atom. O2- is bonded in a bent 120 degrees geometry to one Cu2+ and one C4+ atom.

36 MATERIALS SCIENCE↗
NASA NTRS1974

Spacecraft nitrogen generation

Two spacecraft nitrogen (N2) generation systems based on the catalytic dissociation of hydrazine (N2H4) were evaluated. In the first system, liquid N2H4 is catalytically dissociated to yield an N2 and hydrogen (H2) gas mixture. Separation of the N2/H2 gas mixture to yield N2 and a supply of H2 is accomplished using a polymer-electrochemical N2/H2 separator. In the second system, the N2/H2 gas mixture is separated in a two-stage palladium/silver (Pd/Ag) N2/H2 separator. The program culminated in the successful design, fabrication, and testing of a N2H4 catalytic dissociator, a polymer-electrochemical N2/H2 separator, and a two-stage Pd/Ag N2/H2 separator. The hardware developed was sized for an N2 delivery rate of 6.81 kg/d (15lb/day). Experimental results demonstrated that both spacecraft N2 generation systems are capable of producing 6.81 kg/d (15lb/day) of 99.9% pure N2 at a pressure greater than or equal to 1035 kN/m(2) (150 psia).

Marshall, R. D.↗
NASA NTRS1981

Ionospheric composition: The seasonal anomaly explained

The main photochemical processes of the ionosphere are reanalyzed in the light of laboratory measurements of rate coefficients, using the Atmosphere Explorer data. Major changes to the chemistry include the transfer of nearly all metastable 0(+) ions to N2(+) via charge exchange with N2. The N2(+) ions become vibrationally excited by resonant fluorescence of solar near UV and near infrared radiation, leading to a return transfer of N2(+) ionization to 0(+) by charge exchange or vibrationally excited N2(+) with atomic oxygen. With this chemistry the seasonal variations in the peak electron densities are then shown to be caused primarily by anomalous seasonal variations in neutral composition. The required neutral composition variations are empirically produced by the MSIS model atmosphere. The circulation derived from recent 3D models of the global thermosphere qualitatively accounts for the seasonal variations in neutral composition predicted by the MSIS model. In addition to the composition effect, vibrationally excited N2 is found to contribute a 20% effect to the anomalous seasonal behavior at solar maximum.

Torr, D. G.↗
NASA NTRS1985

Enhanced N(+) Sub 2 in the Shuttle Environment

Observations were made of the N2 first negative and Meinel emission bands with the Imaging Spectrometric Observatory (ISO) on Spacelab 1. These observations have revealed the presence of N2 emissions which exceed those expected on the basis of current ionospheric models by up to a factor of 10. If the emission is of terrestrial origin, large unidentified ionospheric sources of N2 ions must exist. On the other hand, if the source is local to the shuttle environment, a mechanism must be found which is capable of generating emissions of such unexpectedly large intensity. Charge exchange of ambient ionospheric O+ ions with shuttle environmental N2, followed by resonance scattering of sunlight, as a candidate were suggested. However, this model implies that a cloud of N2 gases must surround the vehicle in concentrations in excess of 10 to the 11 c.c. cm with a scale length of tens of meters. In addition, the N2 residence time must be of the order of 10 sec.

Torr, D. G.↗
NASA NTRS1992

Electron beam fluorescence measurements in the Boeing hypersonic shock tunnel

The Calspan electron beam fluorescence (EBF) measurement system is described along with the results of measurements made in hypersonic flow. Numerous self-emitting metallic species were identified, many of which may be associated with an aging/erosion process within the B30HST. Because there were only 16 tunnel runs, it was only possible to obtain spectral measurements over a limited range of wavelengths and time sampling periods. Many spectral features of the flow remain uninvestigated. Because flow self-emission is important to all optical diagnostic techniques, it is recommended that additional spectral studies by performed. The three electron beam-excited species that were identified are nitrogen, helium, and nitric oxide. The high metallic radiation background interfered with attempts to obtain the time-wise variation of N2 density and He radiation with the optical fiber/PMT channels. In the case of the N2 density measurements the result of interference was increased uncertainty. Unfortunately, the interference caused the time-wise He measurements to fail completely. It is recommended that the electron beam be modulated to provide discrimination against the background radiation in future N2 density measurements. Careful data reduction produced useful measurements of N2 vibrational temperature, even though the high background from metallic species significantly increased measurement uncertainty. Perhaps the recommended additional spectral studies would reveal N2(+) First Negative System band-pair regions having less background. Detection of the He arrival was easily accomplished with the spectrometer/array detector system. Because of this, it is recommended that this means of detecting He arrival be used in the future. With proper calibrations of the system an He number density could be obtained. Although the flow conditions were out of limits for the run in which the NO spectrum was recorded, the usefulness of the NO spectrum for determination of free-stream rotational temperature was demonstrated and should be exploited in future experiments. Indeed, based on the strong NO signals, it is recommended that lower resolution NO spectra be obtained to provide a measure of NO vibrational temperature in the same manner that the N2 temperature was obtained.

Price, Linwood L.↗
NASA NTRS1993

Electron-ion continuum-continuum mixing in dissociative recombination

In recent calculations on the dissociative recombination (DR) of the v=1 vibrational level of the ground state of N2(+), N2(+)(v=1) + e(-) yields N + N, we have observed an important continuun-continuum mixing process involving the open channels on both sides of N2(+)(v=1) + e(-) yields N2(+)(v=0) + e(-). In vibrational relaxation by electron impact (immediately above) the magnitude of the cross section depends upon the strength of the interaction between these continua. In DR of the v=1 ion level, these continua can also interact in the entrance channel, and the mixing can have a profound effect upon the DR cross section from v=1, as we illustrate in this paper. In our theoretical calculations of N2(+) DR using multichannel quantum defect theory (MQDT), the reactants and products in the two above equations are described simultaneously. This allows us to calculate vibrational relaxation and excitation cross sections as well as DR cross sections. In order to understand the mixing described above, we first present a brief review of the prior results for DR of the v=0 level of N2(+).

Guberman, Steven L.↗
NASA NTRS1996

Spectroscopic Diagnostics and an Arc Jet Heated Air Plasma

Spectral radiation measurements were made in the range of 200 to 900 nm across a section of the plenum of an arc jet wind tunnel using a series of optical fibers. The spectra contained line radiation from Oxygen and Nitrogen atoms and molecular radiation from N2(+), N2, and NO. Abel inversion technique is used to obtain radial distribution of the spectra. The analysis yielded radial profiles of the electronic excitation, vibrational and rotational temperatures of the flow field. Spectral fitting yielded branching ratios for different vibrational and rotational bands. Relatively mild flow conditions, i.e. enthalpy and mass flow rate, were used for prolonged measurements of up to and over two hours to establish the best experimental methods of temperature determinations. Signal to noise was improved by at least an order of magnitude enabling the molecular vibrational band heads of N2(+) (first negative system), N2 (second positive system), and NO (beta, gamma, delta, and epsilon systems) to be resolved in the lower ultraviolet wavelength regions. The increased signal to noise ratio also enabled partial resolution of the rotational lines of N2(+) and N2 in certain regions of minimal overlap. Comparison of the spectra with theoretical models such as the NEQAIR2 code are presented and show potential for fitting the spectra when reliable calibration is performed for the complete wavelength range.

Mack, Larry Howard, Jr.↗
NASA NTRS2000

Effective Potential Energies and Transport Cross Sections for Interactions of Hydrogen and Nitrogen

The interaction energies for N2-He and N2-H2 are calculated by accurate ab initio methods. The virial coefficient and differential scattering cross section for N2-H2 are calculated; the theoretical results are compared with experimental data. The transport collision integrals for N2-H2 and N2-N2 interactions are calculated and tabulated; the results yield transport coefficients that compare well with measured data. Transport coefficients are found to be determined accurately from the interaction energies for a specific configuration of the molecule formed from the interaction partners. Comparisons with results of measurement and accurate calculations demonstrate that the transport properties of complex molecular interactions can be determined rapidly and fairly accurately from the interaction energies of simpler system using combination rules for the short-range parameters of effective interaction energies and the coefficients for the long-range forces. The coefficients for a two-parameter temperature expansion of diffusion and viscosity are tabulated for a realistic universal potential energy that is based primarily on the results of very accurate calculations of the He-He interaction energy.

Stallcop, James R.↗
NASA NTRS2011

The Development of a CO2 Test Capability in the NASA JSC ARCJet for Mars Reentry Simulation

The Atmospheric Reentry Materials and Structures Evaluation Facility (ARMSEF) located at NASA Johnson Space Center is used for simulating the extreme environment experienced upon reentry for the development and certification of thermal protection systems (TPS). The facility supports a large variety of programs and was heavily leveraged for the certification and operational support of the TPS for the Orbiter and, more recently, the development of the heat shield for CEV. This paper will provide more detail into the heritage of the facility. Unique attributes of the facility include a modular aerodynamically stabilized arc heater and independently controlled O2 and N2 for the test gases. When combining the O2 and N2 in a 23:77 mass ratio respectively the Earth s atmosphere is accurately simulated and via modification of this ratio the investigation of the effects of atomic oxygen on a material s response is possible. In the summer of 2010 a development effort was started to add CO2 as a third independently controlled test gas such that, when combined with N2, opens up the possibility of accurately simulating a Martian reentry environment. This paper will discuss the test facility, especially the arc heater, in more detail. Initial testing involved relatively low concentrations of CO2 combined with N2 for the primary purpose of gathering data to answer two pressing safety concerns. The first being the rate of production of carbon monoxide (CO) within the ejector vacuum system. The main concern was that CO can be flammable and possibly explosive at high enough concentrations and pressures. The hazard control during the development phase involved the use of injecting N2 inside the test chamber diffuser to dilute and reduce the concentration of any and all CO present. A residual gas analyzer (RGA) was used to determine the relative amount of CO in the exhaust gas and provide a conversion rate of CO2 to CO. This paper will discuss in more detail the results of the RGA data and the calculated conversion rate. The second safety concern addressed is the possible formation of hydrogen cyanide (HCN) and cyanide (CN). HCN would primarily be present in the cooling water while the CN would most probably condense onto the interior surfaces of the test chamber. Water samples and wipes of the test chamber surfaces were analyzed by an industrial hygienist for the presence of HCN and CN. His paper will discuss these results in more detail. Throughout this development effort measurements of the CO2:N2 flowfield were made with heat flux and pressure probes and with laser induced fluorescence (LIF) of the atomic oxygen. This paper will discuss these results

DelPapa, Steven V.↗
NASA NTRS2013

Investigating Titan's Atmospheric Chemistry at Low Temperature in Support of the NASA Cassini Mission

Titan's atmosphere, composed mainly of N2 and CH4, is the siege of a complex chemistry induced by solar UV radiation and electron bombardment from Saturn's magnetosphere. This organic chemistry occurs at temperatures lower than 200 K and leads to the production of heavy molecules and subsequently solid aerosols that form the orange haze surrounding Titan. The Titan Haze Simulation (THS) experiment has been developed on the COSMIC simulation chamber at NASA Ames in order to study the different steps of Titan's atmospheric chemistry at low temperature and to provide laboratory data in support for Cassini data analysis. The chemistry is simulated by plasma in the stream of a supersonic expansion. With this unique design, the gas mixture is adiabatically cooled to Titan-like temperature (approx. 150 K) before inducing the chemistry by plasma discharge. Different gas mixtures containing N2, CH4, and the first products of the N2,-CH4 chemistry (C2H2, C2H4, C6H6...) but also heavier molecules such as PAHs or nitrogen containing PAHs can be injected. Both the gas phase and solid phase products resulting from the plasma-induced chemistry can be monitored and analyzed. Here we present the results of recent gas phase and solid phase studies that highlight the chemical growth evolution when injecting heavier hydrocarbon trace elements in the initial N2-CH4 mixture. Due to the short residence time of the gas in the plasma discharge, only the first steps of the chemistry have time to occur in a N2-CH4 discharge. However by adding acetylene and benzene to the initial N2-CH4 mixture, we can study the intermediate steps of Titan's atmospheric chemistry as well as specific chemical pathways. These results show the uniqueness of the THS experiment to help understand the first and intermediate steps of Titan fs atmospheric chemistry as well as specific chemical pathways leading to Titan fs haze formation.

Sciamma-O'Brien, Ella↗
NASA NTRS2015

Assessment of New Load Schedules for the Machine Calibration of a Force Balance

New load schedules for the machine calibration of a six-component force balance are currently being developed and evaluated at the NASA Ames Balance Calibration Laboratory. One of the proposed load schedules is discussed in the paper. It has a total of 2082 points that are distributed across 16 load series. Several criteria were applied to define the load schedule. It was decided, for example, to specify the calibration load set in force balance format as this approach greatly simplifies the definition of the lower and upper bounds of the load schedule. In addition, all loads are assumed to be applied in a calibration machine by using the one-factor-at-a-time approach. At first, all single-component loads are applied in six load series. Then, three two-component load series are applied. They consist of the load pairs (N1, N2), (S1, S2), and (RM, AF). Afterwards, four three-component load series are applied. They consist of the combinations (N1, N2, AF), (S1, S2, AF), (N1, N2, RM), and (S1, S2, RM). In the next step, one four-component load series is applied. It is the load combination (N1, N2, S1, S2). Finally, two five-component load series are applied. They are the load combination (N1, N2, S1, S2, AF) and (N1, N2, S1, S2, RM). The maximum difference between loads of two subsequent data points of the load schedule is limited to 33 % of capacity. This constraint helps avoid unwanted load "jumps" in the load schedule that can have a negative impact on the performance of a calibration machine. Only loadings of the single- and two-component load series are loaded to 100 % of capacity. This approach was selected because it keeps the total number of calibration points to a reasonable limit while still allowing for the application of some of the more complex load combinations. Data from two of NASA's force balances is used to illustrate important characteristics of the proposed 2082-point calibration load schedule.

wind tunnel testing↗
NASA NTRS2011

Excited State Chemistry in the Free Stream of the NASA IHF Arc Jet Facility Observed by Emission Spectroscopy

Spectroscopic measurements of non-equilibrium emission were made in the free stream of the 60 megawatts Interaction Heating Facility at NASA Ames Research Center. In the visible near infrared wavelength region, the most prominent emission was from molecular N2, and in the ultra violet region, the spectra were dominated by emission from molecular NO. The only atomic lines observed were those of copper (an erosion product of the electrodes). The bands of the 1st Positive system of N2 (if B is true then A is true) differed significantly from spectra computed spectra assuming only thermal excitation, suggesting overpopulation of the high vibrational states of the B state of N2. Populations of these high vibrational levels (peaking at v (sub upper) equals 13) of the N2 B state were determined by scaling simulated spectra; calculations were performed for each upper vibrational state separately. The experimental-theoretical procedure was repeated for several radial positions away from the nozzle axis to obtain spatial distributions of the upper state populations; rotational symmetry of the flow was assumed in simulations. The overpopulation of the high vibrational levels has been interpreted as the effect of inverse pre-dissociation of neutral atoms in the N2 A state, which populates the N2 B state through a level crossing process at v (sub upper) is greater than 10.

arc-jet testing↗
NASA NTRS2017

The Chemistry of Pluto and its Satellites

Pluto's bulk composition and the composition of the surface layers hold clues to the origin and evolution of a number of other Solar System bodies of comparable size in the region beyond Neptune. The July 14, 2015 flyby of the Pluto system with the New Horizons spacecraft afforded the opportunity to corroborate and greatly improve discoveries about the planet and its satellites derived Earth-based studies. It also revealed extraordinary details of the surface and atmosphere of Pluto, as well as the geology and composition of Charon and two smaller satellites. With a mean density of 1.86 g/sq cm, the bulk composition of Pluto is about two-thirds anhydrous solar composition rocky material and one-third volatiles (primarily H2O in liquid and solid states) by mass, the surface is a veneer of ices dominated by N2, with smaller amounts of CH4 and CO, as well as limited exposures of H2O ice (considered to be "bedrock"). N2, CH4, and CO occur as solid solutions at temperature-dependent mutual concentrations, each component being soluble in the others. Frozen C2H6 as a minor component has also been identified. Sublimation and recondensation of N2, CH4, and CO over seasonal (248 y) and Milankovich-type megaseasons (approx. 3 My) result in the redistribution of these ices over time and with latitude control. Solid N2 is found in glaciers originating in higher elevations and flowing at the present time into a basin structure larger than the State of Texas, forming a convecting lens of N2 that overturns on a timescale of order 10 My. The varied colors of Pluto's landscape arise from the energetic processing of the surface ices in processes that break the simple molecules and reassemble complex organic structures consisting of groups of aromatic rings connected by aliphatic chains. When synthesized in the laboratory by UV or electron irradiation of a Pluto mix of ice, this material, called tholin, has colors closely similar to Pluto. The Pluto ice tholin analog contains carboxylic acids, urea, ketones, aldehydes, amines, and some nitriles. The largest satellite, Charon has density 1.70 g/sq cm and it is about 3/5 anhydrous solar composition rock, with the remainder in H2O ice. The surface H2O ice is infused in some way with NH3, probably as a hydrate, distributed nonuniformly, but to some degree related to geological structures. Pluto's atmosphere is N2, CH4, with CO, C2-hydrocarbons, HCN, and other molecules in trace but detectable amounts. The atmosphere supports a complex haze structure with about 20 discrete layers, and suspected clouds. The haze is presumed to be made of aggregates of complex hydrocarbons (tholins) produced by photolysis of the atmospheric gases, and with similar composition to the ice tholins made on the planet's surface. Urea and a suite of carboxylic acids are of interest for prebiotic and biological chemistries.

SOLAR SYSTEMS↗
NASA NTRS2013

Compositions of the Surfaces of Pluto and its Satellites

The information we have on the chemical compositions of the surfaces of Pluto and Charon has been obtained from Earth-based near-infrared spectroscopy. These bodies are seen in diffusely scattered sunlight upon which absorption bands diagnostic of specific ices are superimposed. Identified so far on Pluto are molecular nitrogen (N2), methane (CH4), carbon monoxide (CO), and ethane (C2H6), all in the frozen state. Charon has the clear spectral signature of H2O ice in the crystalline phase, plus an absorption band near 2.2 microns identified as a hydrated form of NH3. No diagnostic spectra of Pluto's other satellites are currently available. A fraction of Pluto's CH4 is dissolved in solid N2, which is in the hexagonal beta-phase. When a small concentration of CH4 exists in a N2 crystalline matrix, its absorption bands are shifted in wavelength by a small but detectable amount. Indeed the shifting of the CH4 bands is diagnostic of a host matrix. In the case of Pluto, the N2 band (2.148 microns) itself is detected, but for other trans-Neptunian objects where the N2 band cannot be seen, the shifted CH4 bands demonstrate the presence of N2 or (less likely) some other spectrally neutral and transparent matrix material (e.g., Ar). The absence of detectable CO2 and H2O ices on Pluto, while they are clearly present on the otherwise very similar Triton, is noteworthy. The ices of Pluto distributed non-uniformly across its surface, and the distribution shows long-term (decadal) changes. Both seasonal and secular changes may be occurring through transport across the surface as a result of changing temperature, and by seasonal changes in the vapor pressure equilibrium of the ice with the tenuous and variable atmosphere. Models of the photochemistry of the surface ices and the atmosphere of Pluto predict the presence of several materials not yet detected; the most abundant photoproducts are expected to be C2H2, C4H2, HCN, C2H6; HCN has been detected on Triton. Both Pluto and Charon have surface components in addition to the detected ices. These materials of presently unknown composition serve to reduce the albedos of both bodies below that expected for pure ices, and in the case of Pluto impart a yellow-brown coloration; the color of Charon is more nearly neutral. It is generally thought that the non-ice components are more refractory than the ices and that they may be complex carbonaceous materials derived from the ultraviolet and charged particle processing of the surface ices. Minerals are also plausible candidates for the non-ice fraction. The refractory colored components may constitute bedrock upon which variable amounts of the ices are alternately deposited and evaporated as the seasons change. Water ice is expected to be a component of the bedrock, although it has not yet been reliably identified.

Pluto↗
DOE OSTI2020

Materials Data on B6P2H14N2O19 by Materials Project

B6P2N2H14O19 crystallizes in the triclinic P-1 space group. The structure is one-dimensional and consists of one B6P2N2H14O19 ribbon oriented in the (1, 0, 0) direction. there are three inequivalent B3+ sites. In the first B3+ site, B3+ is bonded to four O2- atoms to form BO4 tetrahedra that share corners with two equivalent PO4 tetrahedra. There is one shorter (1.44 Å) and three longer (1.49 Å) B–O bond length. In the second B3+ site, B3+ is bonded in a trigonal planar geometry to three O2- atoms. There is two shorter (1.37 Å) and one longer (1.40 Å) B–O bond length. In the third B3+ site, B3+ is bonded in a trigonal planar geometry to three O2- atoms. There are a spread of B–O bond distances ranging from 1.35–1.41 Å. P5+ is bonded to four O2- atoms to form PO4 tetrahedra that share corners with two equivalent BO4 tetrahedra. There are a spread of P–O bond distances ranging from 1.49–1.65 Å. N2- is bonded in a tetrahedral geometry to four H1+ atoms. There are a spread of N–H bond distances ranging from 1.03–1.06 Å. There are seven inequivalent H1+ sites. In the first H1+ site, H1+ is bonded in a single-bond geometry to one N2- and one O2- atom. The H–O bond length is 1.67 Å. In the second H1+ site, H1+ is bonded in a single-bond geometry to one O2- atom. The H–O bond length is 1.00 Å. In the third H1+ site, H1+ is bonded in a single-bond geometry to one N2- atom. In the fourth H1+ site, H1+ is bonded in a single-bond geometry to one O2- atom. The H–O bond length is 0.99 Å. In the fifth H1+ site, H1+ is bonded in a single-bond geometry to one N2- atom. In the sixth H1+ site, H1+ is bonded in a single-bond geometry to one N2- atom. In the seventh H1+ site, H1+ is bonded in a single-bond geometry to one O2- atom. The H–O bond length is 0.98 Å. There are ten inequivalent O2- sites. In the first O2- site, O2- is bonded in a distorted bent 120 degrees geometry to one B3+ and one P5+ atom. In the second O2- site, O2- is bonded in a distorted water-like geometry to one P5+ and one H1+ atom. In the third O2- site, O2- is bonded in a distorted bent 120 degrees geometry to one B3+ and one P5+ atom. In the fourth O2- site, O2- is bonded in a distorted bent 120 degrees geometry to one P5+, one H1+, and one O2- atom. The O–O bond length is 3.08 Å. In the fifth O2- site, O2- is bonded in a bent 120 degrees geometry to two B3+ and one O2- atom. The O–O bond length is 3.02 Å. In the sixth O2- site, O2- is bonded in a distorted bent 120 degrees geometry to two B3+ atoms. In the seventh O2- site, O2- is bonded in a bent 120 degrees geometry to one B3+ and one H1+ atom. In the eighth O2- site, O2- is bonded in a bent 120 degrees geometry to one B3+ and one H1+ atom. In the ninth O2- site, O2- is bonded in a bent 120 degrees geometry to two B3+ atoms. In the tenth O2- site, O2- is bonded in a 4-coordinate geometry to four O2- atoms.

36 MATERIALS SCIENCE↗
NASA NTRS1974

The neutral atmosphere temperature experiment

The AEROS Neutral Atmosphere Temperature Experiment (NATE) is designed to measure the kinetic temperature of molecular nitrogen in the thermosphere. A quadrupole mass spectrometer tuned to N2 measures the N2 density variation in a small spherical antechamber having a knife-edged orifice which is exposed to the atmosphere at the outer surface of the spacecraft. The changing density of N2 due to the spinning motion of the spacecraft permits determination of the velocity distribution of the N2 from which the temperature is calculated. An alternate mode of operation of the instrument allows measurement of the other gases in the atmosphere as well as N2 permitting determination of the neutral particle composition of the atmosphere.

Spencer, N. W.↗