The National Academies Press

Currently Skimming:

Pages 18-35

The Chapter Skim interface presents what we've algorithmically identified as the most significant single chunk of text within every page in the chapter.
Select key terms on the right to highlight them within pages of the chapter.

From page 18... ... Commercial Space Vehicle Emissions Modeling 7 2 Literature Review A literature review was conducted to identify sources relevant to commercial space vehicle emissions modeling. Sources were evaluated based on their usefulness in providing:  Emissions data to establish the pollutants emitted by different types of rocket propellants,  Engine performance data to establish the amount of propellant burned, and  Trajectory data to establish the amount of time spent in each altitude band. Read the entire page →
From page 19... ... Commercial Space Vehicle Emissions Modeling 8 temperature include contributions from both the primary and secondary emissions. The commercial space vehicle emissions model is designed to estimate these final emissions, as they are the chemical species that the vehicle ultimately emits into the atmosphere. Read the entire page →
From page 20... ... Commercial Space Vehicle Emissions Modeling 9 Primary Emissions Table 1 summarizes the major primary emissions species produced by each common type of rocket propellant. The primary emissions are the chemical species present at the nozzle exit plane. Read the entire page →
From page 21... ... Commercial Space Vehicle Emissions Modeling 10 minor products of combustion are difficult to accurately measure or model. Thus, these minor species are poorly understood compared to the major primary emissions listed in Table 1. Read the entire page →
From page 22... ... Commercial Space Vehicle Emissions Modeling 11 Emissions Predictions for Historical Launch Vehicles The most detailed emissions results that are publicly available in the literature are analyses of the Space Shuttle (Figure 7) and other NASA launch vehicles. Read the entire page →
From page 23... ... Commercial Space Vehicle Emissions Modeling 12 Emissions Predictions for Current Launch Vehicles The sources listed above are useful for estimating the quantities of pollutants emitted by different types of rocket propellants, but they are not specific to current commercial space vehicles. The following sources include predictions of the emissions for commercial space vehicles and engines:  The 1996 Environmental Assessment (EA) Read the entire page →
From page 24... ... Commercial Space Vehicle Emissions Modeling 13 Black Carbon Emissions Estimates The quantitative emissions data in the sources listed above were predicted based on emissions models, and few of the results were confirmed by measurements. Additionally, most of these sources contained no data for black carbon emissions (Figure 9) Read the entire page →
From page 25... ... Commercial Space Vehicle Emissions Modeling 14 2.2 Engine Performance Data The references provided in the previous section are useful for estimating the concentration of each chemical species emitted by a rocket engine, but the total amount of each species depends on the total amount of propellant burned by the rocket. Thus, the total amount of pollutants emitted into the atmosphere depends on the propellant mass flow rate and burn time. Read the entire page →
From page 26... ... Commercial Space Vehicle Emissions Modeling 15 Engine Performance Data for Commercial Space Vehicles Table 2 lists the sea level thrust, sea level specific impulse, propellant mass per engine, nominal burn time, and estimated initial and average mass flow rates for the first-stage rocket engines of current commercial [46] and historical launch vehicles. Read the entire page →
From page 27... ... Commercial Space Vehicle Emissions Modeling 16 Constant Versus Time-Varying Mass Flow Rate As discussed previously, the thrust and specific impulse vary with time during ascent because they depend on the ambient pressure, which decreases with increasing altitude. However, the mass flow rate is not affected by the ambient conditions outside the nozzle because the exhaust velocity at the nozzle exit plane is supersonic. Read the entire page →
From page 28... ... Commercial Space Vehicle Emissions Modeling 17 for most launch vehicles. For example, Figure 11 shows the normalized mass flow rates for the first stages of the Saturn V rocket during the Skylab 1 mission [66] Read the entire page →
From page 29... ... Commercial Space Vehicle Emissions Modeling 18 The mass, thrust, and structural limits of the launch vehicle determine the maximum acceleration the vehicle can achieve. Within the atmosphere, trajectories are typically designed to use a gravity-turn maneuver, which maintains a zero-degree angle of attack between the vehicle and the flight path. Read the entire page →
From page 30... ... Commercial Space Vehicle Emissions Modeling 19 Table 4. Summary of publicly available historical launch vehicle trajectory data. Read the entire page →
From page 31... ... Commercial Space Vehicle Emissions Modeling 20 Comparison Between Trajectories The trajectory parameters listed in Table 4 were digitized from the graphs and tables contained in the original references. The altitude profiles for the individual Apollo missions were nearly identical to one another, so they were averaged together to create an average Apollo trajectory. Read the entire page →
From page 32... ... Commercial Space Vehicle Emissions Modeling 21 Figure 13. Altitude profiles of similar historical launch vehicles with different target orbits. Read the entire page →
From page 33... ... Commercial Space Vehicle Emissions Modeling 22 Trajectories below the Kármán Line Although the altitude profiles shown in Figure 13 and Figure 14 diverge due to the different target orbits, the most significant differences do not occur until high altitudes. The commercial space vehicle emissions model is only intended to estimate emissions within the atmosphere. Read the entire page →
From page 34... ... Commercial Space Vehicle Emissions Modeling 23 Figure 16. Time duration in each altitude band for historical and publicly available trajectories. Read the entire page →
From page 35... ... Commercial Space Vehicle Emissions Modeling 24 Table 5. Selected software packages for trajectory design and optimization. Read the entire page →

From page 18...

... Commercial Space Vehicle Emissions Modeling 7 2 Literature Review A literature review was conducted to identify sources relevant to commercial space vehicle emissions modeling. Sources were evaluated based on their usefulness in providing:  Emissions data to establish the pollutants emitted by different types of rocket propellants,  Engine performance data to establish the amount of propellant burned, and  Trajectory data to establish the amount of time spent in each altitude band.