astro gr 2

Select all elements common to all space missions based on the Space Mission Architecture

Orbits and Trajectories, Bus, Spacecraft, Launch Vehicles, Mission Operations, The Mission, Goals and Objectives

Which part of the mission describes what we want to accomplish and how well we want to accomplish it

Goals and Objectives

True/False. The spacecraft consists of two main parts. The bus does the mission while the payload provides all the “housekeeping” functions necessary to make the bus work

False

Match the metric to the correct subsystem

Pointing Accuracy = ADCS, Thrust = Propulsion, End

Which of the following do space programs have to budget for in a typical space mission

Cost, Schedule, Performance

Which of the following is a key risk control tool used to absorb unknowns as design matures

Margin

Calculate the best

case resolution (at λmin) in meters (m) for this mission (0.5 µm, 500 km, 0.5 m aperture)

Calculate the worst

case resolution (at λmax = 0.7 µm) in meters (m) for this mission

Calculate the sensor’s field of view (in degrees)

15.19°

Calculate the swath width (in km) for this mission

133.33 km

When altitude changes from 500 km to 300 km, how do payload parameters change

Resolution improves

Swath width degrades

Field of view stays the same

Which imaging payload provides imagery regardless of lighting and can image through clouds and weather

Synthetic Aperture Radar

Electromagnetic (EM) radiation occurs when an electrical charge is _ along an antenna

Accelerated

Electric field lines show the direction and magnitude of force on a test charge

Positive

What is the wavelength of an EM wave with frequency 2.3 GHz

0.130 m

What is 634,723.123 expressed in dB

58.026 dB

What is –12.343 dB expressed as a linear number

0.0583

What is the gain of a 3 m parabolic dish at 1.5 GHz with 60% efficiency

31.25 dB

What is the gain of a helical antenna with 6 turns (Cλ = 1.05, Sλ = 0.27, η = 0.6, f = 3 GHz)

11.09 dB

What is the gain of a 9

element yagi antenna at 954 MHz

Which term means putting information onto a carrier signal

Modulation

The signal loss that results from an RF signal travelling through free

space is called __ loss

When EM energy is radiated from an antenna, it spreads out on the surface of a

Sphere

An RF link from ground to satellite is an ___

Uplink

An RF link from satellite to satellite is a ___

Crosslink

Maximum crosslink range between 500 km and 12,000 km orbits

19,810.39 km

EIRP of 100 W transmitter with 20 dB gain

40 dBW

Free

space loss of 2 GHz signal over 10,000 km

Eb/No of given SATCOM link (3 GHz, 45 W, GT = 23 dB, GR = 32 dB, range 26,000 km, T = 280 K, Rb = 10 Mbps, 6 dB loss)

9.37 dB

Which apply to GPS carrier signals

L Band, LHCP, 1 frequency used for navigation, 5 total carriers

Which are sources of errors for GPS

Relativity, Ionosphere Delay, Troposphere Delay, Multipath

Match the GPS codes – Encrypted = P Code

Single Frequency = C/A Code

Civil and Military = C/A Code

Two Frequencies = P Code

Given station A (0, 0) and B (6, 0), ranges 5 km and 3 km – pilot possible locations

(4.33, 2.49) km and (4.33, –2.49) km

True/False. An open loop system can dynamically adjust inputs to control the output

False

Disturbance torques depending on orientation, current, and magnetic field

Magnetic Torque

Part of closed loop system that compares sensor output to desired output

Controller

True/False. Satellites can receive and use GPS signals in space for attitude determination

True

Examples of ACTIVE attitude actuators

Thrusters, Magnetic Torquers

Examples of PASSIVE attitude actuators

Gravity

Examples of sensors for attitude determination

Sun sensor, Gravity

Ground pointing accuracy for 1000 km altitude, 0.01° payload

0.175 k

Ground pointing accuracy equation

D = …

attitude control section