Test Yourself Questions Flashcards
(27 cards)
What is the strongest perturbation for Low Earth Orbit?
Atmospheric drag.
What are the design requirements of solar sails?
Deployable, large unfolded area, reflective, low mass and small stow size.
What planet in our solar system has the largest SOI?
Neptune. SOI is dependent on both mass and semi major axis.
Why are Type II transfers sometimes more appealing than Type I?
Type II transfers arrive at the target planet with a lower velocity, meaning less energy must be used for the retrograde burn to enter a parked orbit.
What kind of orbit is useful when using a low thrust engine?
Spiral orbit.
What kind of trajectory is a good safety measure for crewed missions?
Free return trajectory. If something were to go wrong then the spacecraft will return to Earth regardless.
What factors are to be considered when designing a ground station?
- Location
- Link data rates
- Requirements for data handling
- Communication between ground station and data users
What is an omnidirectional antenna?
An antenna that radiates power equally in all directions (perpendicular to axis). It is useful when trying to establish communications when altitude is not completely known.
What is the aim of a link budget?
To ensure a suitable margin in the communication system to give an acceptable signal to noise ratio at the receiver.
When is a launch vehicle considered to be successful?
- Accurate placement of payload in the desired orbit
- Keeps forces on the payload within the limits
- Reliable and cheap
What % by mass does the payload take up in a launch vehicle?
1%
How many stages do orbital launchers have?
Usually 2 or 3 main stages, some have additional boosters.
What are the key components of an orbital launcher?
- Engines and combustion chambers
- Propellant tanks and fuel pumps
- Staging adapters
- Booster rockets and stages
- Avionics for guidance navigation and control
- Payload adaptor
- Aerodynamic faring
Why is a 10% mass ratio achievable for individual stages but getting 12.7% for a SSTO reusable launcher hasn’t been achieved yet?
Getting the payload and additional SSTO system within the remaining 2.7% is difficult.
What is Skylon?
Skylon is a SSTO spacecraft that aims to meet the system optimisation goals by using a Sabre engine capable of delivering 6100m/s Isp with a light airframe that achieves a 20% mass ratio.
Which engine cooling methods are not suitable for SSTO reusable launchers?
- Heat sinks (too heavy)
- Radiative (must work in atmosphere)
- Ablative (would require re-application each launch)
What causes combustion instability?
Rough Start - build up of propellant in the chamber before combustion, causes over-pressuring.
Chugging - low frequency oscillations (<100Hz), caused by feed system instabilities.
Screaming - high frequency instability (>1kHz), normally due to injector or chamber problems.
What factors are competing upon re-entry?
- Deceleration (can bee too high as this can kill)
- Heating (high enough to dissipate energy but not too high that it causes damage)
- Accuracy
What entry causes a greater total heating load, shallow or steep?
Shallow. The maximum temperature reached is lower, but the heating occurs for a longer period.
Give an example of a survival spacesuit.
Sokol.
What health problems can occur from being in space?
- Muscle loss
- Fluid and electrolyte problems
- Cardiovascular issues
- Bone degradation
- Radiation damage
Which force, other than the centripetal force, is experienced by astronauts in a rotating spacecraft?
Coriolis force. This can cause disorientation when moving up and down with respect to the circumference of the rotating station.
What is the approximate diameter of payload fairings?
3-5m
Why are science instruments often moved away from the main body of the satellite?
To prevent interference, especially for magnetometers.
