Archives: Glossary Terms

The Russian name for astronaut.

A method to estimate the cost of a space mission by dividing it into pieces and estimating the cost of each piece, then summing the individual costs. The cost of each piece comes from historical data on similar spacecraft. CERs are inexact but a good start for mission planning.

A sequence of project activities that we can’t delay without delaying the project. Activities on the critical pathA sequence of project activities that we can’t delay without delaying the project. Activities on the critical pathA sequence of project activities that we can’t delay without delaying the project. Activities on the critical path have no slack, so they must start and end on time. More have no slack, so they must start and end on timeThe time between successive passages of the Sun overhead, which is from noon one day to noon the next day. Because Earth’s orbit around the Sun is slightly elliptical, this time varies slightly during a year. More. More have no slack, so they must start and […]

The connections that transmit commandsInstruction sets that tell a spacecraft’s computer to take some action or update a critical software part. When a spacecraft receivesa command, it typically stores the command, then re-transmits it to the ground station that sent it, to confirm its validity. More and data between relay satellites, to the primary spacecraft […]

We define currentWe define currentWe define current,i, as the rate at which charges flow through a given area, such as the cross section of a wire. The unit for current is amperes (amps), which equals the charges flowing per second. More,i, as the rate at which charges flow through a given area, such as the cross section of a wire. The unit for currentWe define current,i, as the rate at which charges flow through a given area, such as the cross section of a wire. The unit for current is amperes (amps), which equals the charges flowing per second. More is amperes (amps), which equals the charges flowing per second. More,i, as the rate at which charges flow through a given area, such as the cross section […]

The mission users, or customers, are the people who will benefit from the mission.

Dampers “absorb” unwanted angular momentumThe total angular momentumThe total angular momentum that a spacecraft may use during its mission lifetime to adjust its attitude, so its payload can point correctly. More that a spacecraft may use during its mission lifetime to adjust its attitude, so its payloadAn assembly of spacecraft components that collect, process, store, and transmit payload-mission and bus-housekeeping data. The communication and data-handling subsystem (CDHS) acts as the ears, brain, and mouth of the spacecraft • It has two primary portions — communication and data handling • It translates raw data from the payloads and subsystems into useful information and sends it to the ground system • Commands from ground controllers generally request information from and give specific instructions to individual subsystems More can pointThe job of the attitude determination and control subsystem (ADCS) is to keep its spacecraft pointed in the right direction. More correctly. More changes by converting the energyWe use the angle of incidenceWe use the angle of incidence, θ, to determine how much solar energy hits a solar panel. This angle lies between a line perpendicular to the cell and the Sun line. More, θ, to determine how much solarWe use the angle of incidence, θ, to determine how much solar energy hits a solar panel. This angle lies between a line perpendicular to the cell and the Sun line. More energyWe use the angle of incidence, θ, to determine how much solar energy hits a solar panel. This angle lies between a line perpendicular to the cell and the Sun line. More hits a solarWe use the angle of incidence, θ, to determine how much solar energy hits a solar panel. This angle lies between a line perpendicular to the cell and the Sun line. More panelWe use the angle of incidence, θ, to determine how much solar energy hits a solar panel. This angle lies between a line perpendicular to the cell and the Sun line. More. This angleWe use the angle of incidence, θ, to determine how much solar energy hits a solar panel. This angle lies between a line perpendicular to the cell and the Sun line. More lies between a line […]

The speedHow fast an object’s speed is changing when we apply a force to it. During accelerationHow fast an object's speed is changing when we apply a force to it. During acceleration, speed increases. During deceleration, speed decreases. More, speed increases. During decelerationThe narrow, 3-dimensional tunnel a vehicle must fly through to successfully re-enter Earth’s atmosphere. It’s boundaries come from limits on the vehicle’s maximum deceleration, maximum heating, and expected landing accuracy. More, speed decreasesThe amount of air within a certain volume. Atmospheric density is higher at sea-level and decreases as you go up in altitude. More. More and storage specifications for the communicationAn assembly of spacecraft components that collect, process, store, and transmit payload-mission and bus-housekeeping data. The communication and data-handling subsystem (CDHS) acts as the ears, brain, and mouth of the spacecraft • It has two primary portions — communication and data handling • It translates raw data from the payloads and subsystems into useful information and sends it to the ground system • Commands from ground controllers generally request information from and give specific instructions to individual subsystems More and data-handling subsystemAn assembly of spacecraft components that collect, process, store, and transmit payload-mission and bus-housekeeping data. The communication and data-handling subsystemAn assembly of spacecraft components that collect, process, store, and transmit payload-mission and bus-housekeeping data. The communication and data-handling subsystem (CDHS) acts as the ears, brain, and mouth of the spacecraft • It has two primary portions — communication and data handling • It translates raw data from the payloads and subsystems into useful information and sends it to the ground system • Commands from ground controllers generally request information from and give specific instructions to individual subsystems More (CDHS) acts as […]