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53-446: The ICESat-2 mission is designed to provide elevation data needed to determine ice sheet mass balance as well as vegetation canopy information. It will provide topography measurements of cities, lakes and reservoirs, oceans and land surfaces around the globe, in addition to the polar-specific coverage. ICESat-2 also has the ability to detect seafloor topography up to 100 feet (30m) below the surface in clear watered coastal areas. Because

106-457: A [ B ] b = K e q {\displaystyle {\frac {k_{1}}{k_{-1}}}={\frac {[\mathrm {C} ]^{c}[\mathrm {D} ]^{d}}{[\mathrm {A} ]^{a}[\mathrm {B} ]^{b}}}=K_{eq}} Plankton, Aerosol, Cloud, ocean Ecosystem Plankton, Aerosol, Cloud, ocean Ecosystem ( PACE ) is a 2020s NASA Earth-observing satellite mission to observe global ocean color, biogeochemistry , and ecology , as well as

159-406: A [ B ] b {\displaystyle r_{1}=k_{1}[\mathrm {A} ]^{a}[\mathrm {B} ]^{b}} and the backward reaction rate as r − 1 = k − 1 [ C ] c [ D ] d {\displaystyle r_{-1}=k_{-1}[\mathrm {C} ]^{c}[\mathrm {D} ]^{d}} The rate at which substance A

212-430: A bit more complicated. In the first example, we will show how to use a mass balance to derive a relationship between the percent excess air for the combustion of a hydrocarbon-base fuel oil and the percent oxygen in the combustion product gas. First, normal dry air contains 0.2095  mol of oxygen per mole of air, so there is one mole of O 2 in 4.773 mol of dry air. For stoichiometric combustion,

265-409: A fed-batch reactor some reactants/ingredients are added continuously or in pulses (compare making porridge by either first blending all ingredients and then letting it boil, which can be described as a batch reactor, or by first mixing only water and salt and making that boil before the other ingredients are added, which can be described as a fed-batch reactor). Mass balances for fed-batch reactors become

318-429: A large range of temperatures. The telescope collects photons with wavelength of 532 nm, thus filters out irrelevant light in the atmosphere. Computer programs further identify 532 nm photons in the dataset; only reflected photons of the laser are kept for analysis. A notable attribute of ATLAS is that engineers enabled the satellite to control how it is positioned in space, which is relevant because ATLAS records

371-576: A liquid phase reaction we can (usually) assume a constant volume and since n A = V ∗ C A {\displaystyle n_{\rm {A}}=V*C_{\rm {A}}} we get r A V = V d C A d t {\displaystyle r_{\rm {A}}V=V{\frac {dC_{\rm {A}}}{dt}}} or r A = d C A d t {\displaystyle r_{\rm {A}}={\frac {dC_{\rm {A}}}{dt}}} In many textbooks this

424-1040: A significant milestone for the next stage was that the official mission budget became available for use on 1 July 2016. PACE has two fundamental science goals: "to extend key systematic ocean color, aerosol, and cloud data records for Earth system and climate studies, and to address new and emerging science questions using its advanced instruments, surpassing the capabilities of previous and current missions". The ocean and atmosphere are directly connected, moving and transferring energy, water, nutrients, gases, aerosols, and pollutants. Aerosols, clouds, and phytoplankton can also affect one another. PACE will measure atmospheric particles and clouds that scatter and absorb sunlight. Improved characterization of aerosol particles will enable quantifying their impact on marine biology and ocean chemistry , as well as Earth's energy budget and ecological forecasting . PACE will enable scientists to better monitor fisheries, identify harmful algal blooms , and observe changes in marine resources. The color of

477-521: A substance A becomes IN + PROD = OUT + ACC 0 + r A V = 0 + d n A d t {\displaystyle {\begin{array}{ccccccc}{\text{IN}}&+&{\text{PROD}}&=&{\text{OUT}}&+&{\text{ACC}}\\0&+&r_{\rm {A}}V&=&0&+&\displaystyle {\frac {dn_{\rm {A}}}{dt}}\end{array}}} where In

530-431: A system must, by conservation of mass, either leave the system or accumulate within the system . Mathematically the mass balance for a system without a chemical reaction is as follows: Input = Output + Accumulation {\displaystyle {\text{Input}}={\text{Output}}+{\text{Accumulation}}} Strictly speaking the above equation holds also for systems with chemical reactions if

583-473: Is 3.3 km (2.1 mi) apart across the beam track, and each beam in a pair is separated by 2.5 km (1.6 mi) along the beam track. The laser array is rotated 2 degrees from the satellite's ground track so that a beam pair track is separated by about 90 m (300 ft). The laser pulse rate combined with satellite speed results in ATLAS taking an elevation measurement every 70 cm (28 in) along

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636-492: Is crushed then sieved to only allow fine particles out of the circuit and the larger particles are returned to the roller mill (grinder). However, recycle flows are by no means restricted to solid mechanics operations; they are used in liquid and gas flows, as well. One such example is in cooling towers , where water is pumped through a tower many times, with only a small quantity of water drawn off at each pass (to prevent solids build up) until it has either evaporated or exited with

689-446: Is designed to engage people and organizations who plan to use the data, before the satellite launches. Selected from a pool of applicants, this Science Definition Team represents experts in a wide variety of scientific fields including hydrology, atmospheric science, oceanography, and vegetation science. Early Adopters in the program, including ice scientists, ecologists, and the Navy, work with

742-406: Is given as the definition of reaction rate without specifying the implicit assumption that we are talking about reaction rate in a closed system with only one reaction. This is an unfortunate mistake that has confused many students over the years. According to the law of mass action the forward reaction rate can be written as r 1 = k 1 [ A ]

795-418: Is given below; note that it simplifies to the earlier equation in the case that the generation term is zero. Input + Generation = Output + Accumulation   + Consumption {\displaystyle {\text{Input}}+{\text{Generation}}={\text{Output}}+{\text{Accumulation}}\ +{\text{Consumption}}} A simple example can illustrate the concept. Consider

848-732: Is produced is thus r A = a ( r − 1 − r 1 ) {\displaystyle r_{\mathrm {A} }=a(r_{-1}-r_{1})} and since, at equilibrium, the concentration of A is constant we get r A = a ( r − 1 − r 1 ) = d C A d t = 0 {\displaystyle r_{\mathrm {A} }=a(r_{-1}-r_{1})={\frac {dC_{\mathrm {A} }}{dt}}=0} or, rearranged k 1 k − 1 = [ C ] c [ D ] d [ A ]

901-479: Is used to design chemical reactors , to analyse alternative processes to produce chemicals, as well as to model pollution dispersion and other processes of physical systems. Mass balances form the foundation of process engineering design. Closely related and complementary analysis techniques include the population balance , energy balance and the somewhat more complex entropy balance. These techniques are required for thorough design and analysis of systems such as

954-598: The Plankton, Aerosol, Cloud, ocean Ecosystem (PACE) satellite. The launch of ICESat-2 took place on 15 September 2018 at 15:02 UTC from Vandenberg Air Force Base Space Launch Complex 2 aboard a Delta II 7420-10C. To maintain a degree of data continuity between the decommissioning of ICESat and the launch of ICESat-2, NASA's airborne Operation IceBridge used a variety of aircraft to collect polar topography and measure ice thickness using suites of laser altimeters, radars, and other systems. ICESat-2's Applications program

1007-446: The carbon cycle , aerosols and clouds . PACE is intended to be used to identify the extent and duration of phytoplankton blooms and improve understanding of air quality. These and other uses of PACE data are expected to benefit the economy and society according to NASA, especially sectors that rely on water quality , fisheries and food security . Despite being proposed for cancellation under President Trump's FY 2018 budget,

1060-414: The refrigeration cycle . In environmental monitoring , the term budget calculations is used to describe mass balance equations where they are used to evaluate the monitoring data (comparing input and output, etc.). In biology , the dynamic energy budget theory for metabolic organisation makes explicit use of mass and energy balance. The general form quoted for a mass balance is The mass that enters

1113-1319: The AFR = 16.75, and the mass of the combustion product gas is 17.75 kg , which contains 0.505 kg of excess oxygen. The combustion gas thus contains 2.84 percent O 2 by mass. The relationships between percent excess air and % O 2 in the combustion gas are accurately expressed by quadratic equations, valid over the range 0–30 percent excess air: %  excess air = 1.2804 × ( % O 2  in combustion gas ) 2 + 4.49 × ( % O 2  in combustion gas ) % O 2  in combustion gas = − 0.00138 × ( %  excess air ) 2 + 0.210 × ( %  excess air ) {\displaystyle {\begin{aligned}&\%{\text{ excess air}}=1.2804\times (\%{\ce {O2}}{\text{ in combustion gas}})^{2}+4.49\times (\%{\ce {O2}}{\text{ in combustion gas}})\\[4pt]&\%{\ce {O2}}{\text{ in combustion gas}}=-0.00138\times (\%{\text{ excess air}})^{2}+0.210\times (\%{\text{ excess air}})\end{aligned}}} In

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1166-555: The ICESat-2 applications team to provide information on how the satellite observations can be used. The goal of this group is to communicate the vast capabilities of the ICESat-2 mission with the greater scientific community, with the aim to diversify and innovate new methods and techniques from the collected data. For example, scientists in the ecology field will be able to use the measurement of vegetation height, biomass, and canopy cover derived from ICESat-2's photon counting lidar (PCL). In

1219-593: The accuracy of typical analytical procedures, an equation for the mass of air per mass of fuel at stoichiometric combustion is: mass of air mass of fuel = A F R mass = 11.5 w C + 34.3 w H + ( w S − w O ) {\displaystyle {\frac {\text{mass of air}}{\text{mass of fuel}}}=\mathrm {AFR} _{\text{mass}}=11.5\,w_{\rm {C}}+34.3\,w_{\rm {H}}+(w_{\rm {S}}-w_{\rm {O}})} where w C , w H , w S , w O refer to

1272-540: The analysis of physical systems . By accounting for material entering and leaving a system, mass flows can be identified which might have been unknown, or difficult to measure without this technique. The exact conservation law used in the analysis of the system depends on the context of the problem, but all revolve around mass conservation, i.e., that matter cannot disappear or be created spontaneously. Therefore, mass balances are used widely in engineering and environmental analyses . For example, mass balance theory

1325-471: The applications of the differential mass balance: The ideal completely mixed batch reactor is a closed system. Isothermal conditions are assumed, and mixing prevents concentration gradients as reactant concentrations decrease and product concentrations increase over time. Many chemistry textbooks implicitly assume that the studied system can be described as a batch reactor when they write about reaction kinetics and chemical equilibrium . The mass balance for

1378-554: The conventional form of this equation is written to account for both a positive generation term (i.e. product of reaction) and a negative consumption term (the reactants used to produce the products). Although overall one term will account for the total balance on the system, if this balance equation is to be applied to an individual species and then the entire process, both terms are necessary. This modified equation can be used not only for reactive systems, but for population balances such as arise in particle mechanics problems. The equation

1431-583: The distance from itself to the ground, and if its position is off, the measurement recorded for Earth's elevation will be off as well. Engineers also constructed the laser reference system, which confirms that the laser is adjusted in accordance to the telescope. If either the telescope or the laser is off, the satellite can make its own adjustments accordingly. The National Snow and Ice Data Center Distributed Active Archive Center manages ICESat-2 science data. ICESat-2 has four science objectives: In addition, ICESat-2 will take measurements of clouds and aerosols,

1484-474: The drawn off water. The mass balance for water is M = D + W + E . The use of the recycle aids in increasing overall conversion of input products, which is useful for low per-pass conversion processes (such as the Haber process ). A mass balance can also be taken differentially . The concept is the same as for a large mass balance, but it is performed in the context of a limiting system (for example, one can consider

1537-481: The following years, technical issues with the mission's only onboard instrument, ATLAS, delayed the mission further, pushing the expected launch back from late 2016 to May 2017. In July 2014, NASA submitted a report to Congress detailing the reasons for the delay and a projected budget overrun, as is required by law for NASA projects which spend at least 15% over budget. In order to finance the budget overrun, NASA diverted funds from other planned satellite missions, such as

1590-399: The global economy. To understand changes in ocean health related to climate change; formulation of science objectives and sensor requirements for an advanced ocean biology satellite mission began in the year 2000 with a NASA agency-wide carbon cycle initiative that included ocean, terrestrial, and atmospheric disciplines. The instrument requirements for this ocean ecology mission are: PACE

1643-412: The great changes of polar ice cover in global warming are not quantified, one of the main purposes of ICESat-2 is measuring the changing of the elevation of ice sheets by its laser system and lidar to quantify the influence of melting ice sheet in sea-level raising. Additionally, the high accuracy of multiple pulses allows collecting measurement of the heights of sea ice to analyze its change rate during

ICESat-2 - Misplaced Pages Continue

1696-425: The height of oceans, inland water bodies like reservoirs and lakes, cities, and ground movements after events like earthquakes or landslides. ICESat-2 is a follow-up to the original ICESat mission, which was decommissioned in 2010. When the project entered its first phase in 2010, it was expected to be ready for launch as soon as 2015. In December 2012, NASA reported that they expected the project to launch in 2016. In

1749-615: The introduction of the Autonomous Flight Safety System on the Falcon rockets. PACE was the first US government mission to launch to a polar orbit from Florida since 1960. The choice to launch PACE from Florida was simply a matter of convenience, due to it being located closer to the Goddard Space Flight Center , where the mission is operated. The cost of the launch was $ 80.4 million. After launch PACE entered

1802-403: The launch site, where it will be refurbished and reused on future flights. This was the fourth flight of this particular booster, which is designated B1081 . The second stage of the rocket-propelled PACE into its final orbit at an altitude of 676.5 kilometers and the spacecraft was separated about 13 minutes after launch. Unusual for an east coast launch, this was a polar launch that placed

1855-495: The limiting case in time or, more commonly, volume). A differential mass balance is used to generate differential equations that can provide an effective tool for modelling and understanding the target system. The differential mass balance is usually solved in two steps: first, a set of governing differential equations must be obtained, and then these equations must be solved, either analytically or, for less tractable problems, numerically. The following systems are good examples of

1908-425: The mass fraction of each element in the fuel oil, sulfur burning to SO 2 , and AFR mass refers to the air-fuel ratio in mass units. For 1  kg of fuel oil containing 86.1% C, 13.6% H, 0.2% O, and 0.1% S the stoichiometric mass of air is 14.56 kg , so AFR = 14.56. The combustion product mass is then 15.56 kg . At exact stoichiometry, O 2 should be absent. At 15 percent excess air,

1961-449: The mass has been distributed in the system with only limited information and using the mass balance relations across the system boundaries. The mass balance for this system can be described in a tabular form: Mass balances can be performed across systems which have cyclic flows. In these systems output streams are fed back into the input of a unit, often for further reprocessing. Such systems are common in grinding circuits, where grain

2014-533: The mission is $ 964 million, which includes spacecraft construction, launch, and operations. PACE successfully launched on 8 February 2024 at 06:33 UTC . On 17 April 2024 it was announced that first operational data was received. The Pre-Aerosol, Cloud, and ocean Ecosystem satellite (PACE) was approved to move forward out of its preliminary stage of planning on 16 June 2016 at the Key Decision Point-A (KDP-A) event. According to project manager Andre Dress,

2067-417: The ocean is determined by the interaction of sunlight with substances or particles present in seawater such as chlorophyll , a green pigment found in most phytoplankton species. By monitoring global phytoplankton distribution and abundance, the mission will contribute toward understanding the complex systems that drive ocean ecology . The oceans play a critical role in supporting life on Earth as well as

2120-417: The program was funded by Congress in 2018. The PACE project is managed by NASA Goddard Space Flight Center . The main instrument and bus were designed and built at Goddard Space Flight Center. On 4 February 2020, NASA announced the selection of SpaceX to launch PACE on a Falcon 9 , at a total cost to NASA of US$ 80.4 million, including the launch service and other mission-related costs. The total cost of

2173-1091: The relationships between the mass of air and the mass of each combustible element in a fuel oil are: Carbon: mass of air mass of C = 4.773 × 28.96 12.01 = 11.51 Hydrogen: mass of air mass of H = 1 4 ( 4.773 ) × 28.96 1.008 = 34.28 Sulfur: mass of air mass of S = 4.773 × 28.96 32.06 = 4.31 {\displaystyle {\begin{array}{rccc}{\text{Carbon:}}&{\frac {\text{mass of air}}{\text{mass of C}}}&=&{\frac {4.773\times 28.96}{12.01}}&=&11.51\\[2pt]{\text{Hydrogen:}}&{\frac {\text{mass of air}}{\text{mass of H}}}&=&{\frac {{\frac {1}{4}}(4.773)\times 28.96}{1.008}}&=&34.28\\[6pt]{\text{Sulfur:}}&{\frac {\text{mass of air}}{\text{mass of S}}}&=&{\frac {4.773\times 28.96}{32.06}}&=&4.31\end{array}}} Considering

ICESat-2 - Misplaced Pages Continue

2226-485: The satellite to Earth and back; computer programs use the travel time from multiple pulses to determine elevation. ATLAS emits visible laser pulses at 532 nm wavelength ( Green ). As ICESat-2 orbits, ATLAS generates six beams arranged in three pairs in order to better determine the surface's slope and provide more ground coverage. Its predecessor, ICESat , had only one laser beam. The greater number of lasers allows for improved coverage of Earth's surface. Each beam pair

2279-444: The satellite's ground path. The laser fires at a rate of 10 kHz. Each pulse sends out about 20 trillion photons, almost all of which are dispersed or deflected as the pulse travels to Earth's surface and bounces back to the satellite. About a dozen photons from each pulse return to the instrument and are collected with a 79 cm (2.6 ft) beryllium telescope. Beryllium has high specific strength and holds its shape across

2332-959: The second example, we will use the law of mass action to derive the expression for a chemical equilibrium constant. Assume we have a closed reactor in which the following liquid phase reversible reaction occurs: a A + b B ↔ c C + d D {\displaystyle a\mathrm {A} +b\mathrm {B} \leftrightarrow c\mathrm {C} +d\mathrm {D} } The mass balance for substance A becomes IN + PROD = OUT + ACC 0 + r A V = 0 + d n A d t {\displaystyle {\begin{array}{ccccccc}{\text{IN}}&+&{\text{PROD}}&=&{\text{OUT}}&+&{\text{ACC}}\\0&+&r_{\rm {A}}V&=&0&+&\displaystyle {\frac {dn_{\mathrm {A} }}{dt}}\end{array}}} As we have

2385-407: The situation in which a slurry is flowing into a settling tank to remove the solids in the tank. Solids are collected at the bottom by means of a conveyor belt partially submerged in the tank, and water exits via an overflow outlet. In this example, there are two substances: solids and water. The water overflow outlet carries an increased concentration of water relative to solids, as compared to

2438-399: The slurry inlet, and the exit of the conveyor belt carries an increased concentration of solids relative to water. Assumptions Analysis Suppose that the slurry inlet composition (by mass) is 50% solid and 50% water, with a mass flow of 100  kg / min . The tank is assumed to be operating at steady state, and as such accumulation is zero, so input and output must be equal for both

2491-453: The solids and water. If we know that the removal efficiency for the slurry tank is 60%, then the water outlet will contain 20  kg / min of solids (40% times 100  kg / min times 50% solids). If we measure the flow rate of the combined solids and water, and the water outlet is shown to be 65  kg / min , then the amount of water exiting via the conveyor belt must be 5  kg / min . This allows us to completely determine how

2544-480: The spacecraft into a Sun-synchronous orbit , a type of orbit commonly used on observation satellites because it sees a given spot on Earth at the same time every day. These launches are usually carried out from Vandenberg Space Force Base in California , to prevent debris from landing on populated areas, but SpaceX resumed polar launches from Florida in 2020 because of its ability to land the Falcon 9 booster safely and

2597-486: The spring of 2020, NASA selected the ICESat-2 Science Team through a competitive application process, to replace the pre-launch Science Definition Team. This group acts as an advisory board to the mission post-launch, in an effort to ensure the mission science requirements are met. Mass balance In physics , a mass balance , also called a material balance , is an application of conservation of mass to

2650-610: The terms in the balance equation are taken to refer to total mass, i.e. the sum of all the chemical species of the system. In the absence of a chemical reaction the amount of any chemical species flowing in and out will be the same; this gives rise to an equation for each species present in the system. However, if this is not the case then the mass balance equation must be amended to allow for the generation or depletion (consumption) of each chemical species. Some use one term in this equation to account for chemical reactions, which will be negative for depletion and positive for generation. However,

2703-518: The time. The ICESat-2 spacecraft was built and tested by Northrop Grumman Innovation Systems in Gilbert, Arizona, while the on board instrument, ATLAS, was built and managed by Goddard Space Flight Center in Greenbelt, Maryland . The ATLAS instrument was designed and built by the center, and the bus was built by and integrated with the instrument by Orbital Sciences (later Orbital ATK ). The satellite

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2756-410: Was launched on 8 February 2024, at 06:33 UTC instantaneous launch window , on a SpaceX Falcon 9 rocket from Cape Canaveral Space Launch Complex 40 , after two days of delays caused by bad weather. Shortly after launch, the rocket performed a dogleg maneuver to place it in a southbound trajectory. After first stage separation, the Falcon 9 booster performed a boostback burn and returned to land on

2809-557: Was launched on a Delta II rocket provided by United Launch Alliance . This was the last launch of the Delta II rocket. The sole instrument on ICESat-2 is the Advanced Topographic Laser Altimeter System (ATLAS), a space-based lidar . It was designed and built at Goddard Space Flight Center, with the laser generation and detection systems provided by Fibertek. ATLAS measures the travel time of laser photons from

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