2nd Half of Lectures Flashcards
What are the functions of a ground station?
- Support the space segment:
- Command and control
- Monitor spacecraft health (temp, pressure, power)
- Tracking orbital position
- Determine attitude - To relay mission to data users
What is a ground station oscillator?
A device that generates the RF that is to be transmitted and which will act as the carrier of information.
What is ground station modulation?
How information is added onto a radio wave in order to transmit that information.
What is a ground station downconverter?
Shifts the frequency of the radio wave down from GHz to MHz so that it can interface with the receiver.
What are the design considerations for ground stations?
- Location
- Coverage
- Horizon mask
- Data (user needs)
- Cost
- Accessibility for maintenance
- Availability - Link data rates
- Requirements for data handling
- Communication between ground system elements and data users
What are the problems with current scramjet technology?
- Can break through the momentum drag barrier but thrust : weight ratio is worse than jets
- Only work once at M > 5
- Can only go up to M = 7, needs to increase to M = 15
What are pump fed propellant systems?
- Propellant is delivered to chamber via pump
- These allow lower storage pressures and higher chamber pressures making the system lighter
- More complex
- Pumps are powered from the main propellant
- Open and closed loop devices
What is an open loop pump fed system?
Exhaust is dumped overboard.
What is a closed loop pump fed system?
Exhaust is introduced back to the main chamber to be expanded by the nozzle system.
How are deceleration, heating and accuracy managed upon reentry?
By altering the entry angle, thermal protection and vehicle size/shape.
Give two thermal protection materials.
- Reinforced Carbon-Carbon for > 1200C
- Silica ceramics (HRSI tiles) for < 1200C
What is a pure ballistic body?
Symmetric, therefore no lift component.
What is a semi-ballistic body?
Asymmetry due to an offset CoM means some lift is produced to reduce velocity and expose more area.
What is a winged body?
Reentry vehicles that have wings so heat is reduced (more area) and accuracy is improved.
What are the ECLSS functions?
- Atmosphere
- Cabin pressure
- Gas composition
- Oxygen supply
- Temperature
- Remove humidity
- Remove CO2 and contaminants
- Ventilation
- Monitor atmosphere parameters
- Fire detection and suppression - Water
- Provide potable water
- Store, distribute and monitor supply
- Collect condensate from atmosphere
