Self-Assessment Quiz: Ground Operations and Mission Control

Twenty questions to check your grasp of launch operations, the control-room roles, flight dynamics, telemetry and commanding, anomaly resolution, and communication latency. Answer each before opening the key. Aim for 16 or more. Use $c = 2.998\times10^{5}\ \text{km/s}$ and $1\ \text{AU} = 1.496\times10^{8}\ \text{km}$.

Question 1

In a mission-control room, the person with final authority and the only one permitted to break a flight rule is the:

A) CAPCOM B) Flight Director (FLIGHT) C) Flight Dynamics Officer (FIDO) D) EECOM

Question 2

Telemetry is best described as:

A) instructions sent up to the spacecraft B) the stream of measurements the spacecraft sends down about its own state C) the light-time delay of a signal D) the countdown sequence

Question 3

Commanding is:

A) the downlink of the vehicle's vital signs B) the process of determining the orbit C) the uplink of instructions to the spacecraft D) the assignment of console roles

Question 4

The one-way communication latency to a spacecraft at distance $d$ is:

A) $2d/c$ B) $d/c$ C) $c/d$ D) $d/(2c)$

Question 5

Roughly what is the one-way light time to the Moon (mean distance $384{,}400\ \text{km}$)?

A) $0.13\ \text{s}$ B) $1.3\ \text{s}$ C) $13\ \text{s}$ D) $1.3\ \text{min}$

Question 6

At Mars conjunction (Mars on the far side of the Sun), the one-way light time is closest to:

A) $1.3\ \text{s}$ B) $4\ \text{min}$ C) $21\ \text{min}$ D) $8\ \text{h}$

Question 7

The single most important reason deep-space missions must operate autonomously is:

A) the Deep Space Network is expensive B) round-trip light time makes real-time control physically impossible C) spacecraft computers are faster than ground computers D) radios do not work far from Earth

Question 8

The console that owns trajectory, orbit, and maneuver planning is:

A) EECOM B) CAPCOM C) FIDO (Flight Dynamics Officer) D) SURGEON

Question 9

The usual first response to a serious spacecraft anomaly is to:

A) immediately command a repair B) safe the vehicle (e.g., enter safe mode) to stop things getting worse C) end the mission D) switch off telemetry to save power

Question 10

"Verifying a command in the telemetry" means:

A) sending the command twice B) checking that the downlink shows the state change the command was meant to cause C) encrypting the command D) reading the command back over voice loop

Question 11

A satellite in a $400\ \text{km}$ LEO passes over a single ground station for a maximum of about:

A) 1 minute B) 10 minutes C) 1 hour D) continuously

Question 12

Encapsulation, in launch operations, refers to:

A) sealing the spacecraft inside the payload fairing B) loading cryogenic propellant C) the final GO/NO-GO poll D) separating the first stage

Question 13

CAPCOM is traditionally an astronaut because:

A) astronauts are cheaper to employ B) a trained crewmate provides a single, trusted voice to the crew C) only astronauts can read telemetry D) it is required by international law

Question 14

A burn that must occur at a precise instant is best executed by:

A) a real-time "burn now" voice call from the ground B) a time-tagged command the vehicle runs on its own clock C) waiting for the next ground pass D) the range safety officer

Question 15 (True/False, justify)

"In low Earth orbit, the speed-of-light delay is the main thing limiting real-time control." True or false? Justify in one sentence.

Question 16 (True/False, justify)

"During a Mars landing near conjunction, the control room can watch the descent live and abort if needed." True or false? Explain with the approximate light time.

Question 17 (True/False, justify)

"Flight dynamics invents new physics that the earlier orbital-mechanics chapters did not cover." True or false? Say what flight dynamics actually is.

Question 18 (Short answer)

Launch operations is described as "largely irreversible." Give one concrete example from the countdown or propellant-loading phase that illustrates why, and one thing operations does to manage that irreversibility.

Question 19 (Short answer)

A probe downlinks at $1\ \text{Mbit/s}$ and gets a single $5$-minute pass. How many megabytes reach the ground? Show the arithmetic, and state what the spacecraft must do if it generates more data than that between passes.

Question 20 (Short answer)

In your own words, state the chapter's central operational idea: as distance (and therefore latency) grows, how does the nature of control change, and what onboard capability becomes mandatory?

Answer Key

Q Ans Note
1 B FLIGHT integrates all consoles and holds final authority; only FLIGHT may break a flight rule.
2 B Telemetry = the downlinked vital signs; commanding is the reverse.
3 C Commanding = uplinked instructions; telemetry is the reverse.
4 B One-way latency $= d/c$; round trip $= 2d/c$.
5 B $384{,}400 / 2.998\times10^{5} \approx 1.28\ \text{s}$.
6 C $\sim 2.52\ \text{AU} \Rightarrow 3.78\times10^{8}/2.998\times10^{5} \approx 1{,}260\ \text{s} \approx 21\ \text{min}$.
7 B Latency, not cost or hardware, is the physical barrier to real-time control.
8 C FIDO owns "where is it and where is it going," and the burns to change it.
9 B Safe first: stabilize the vehicle and buy time before diagnosing.
10 B Commanding is open-loop until telemetry confirms the resulting state change.
11 B Horizon-to-horizon overhead pass $\approx 10\ \text{min}$; usable pass $\sim 5$–$8\ \text{min}$.
12 A Encapsulation seals the payload inside its fairing; after it, the payload is largely unseen.
13 B One coherent, trusted voice to the crew; advice funnels through FLIGHT to CAPCOM.
14 B Time-tag it to the vehicle's clock; a light-delayed "now" cannot hit a precise instant.
15 False In LEO light time is only milliseconds; real-time control is limited by contact windows (few-minute passes) and relay/ground routing, not by light delay.
16 False One-way light time near conjunction is $\sim 21\ \text{min}$ (round trip $\sim 42\ \text{min}$); the landing (minutes) is over before Earth even sees it begin — descent must be autonomous.
17 False Flight dynamics is the operational application of Chapters 10/12/13 — orbit determination and maneuver planning run continuously against a live vehicle; no new physics.
18 — Example: once cryogenic propellant is loaded and the terminal count is running, you cannot pause for long (boiloff, thermal cycling) — you hold, scrub, or go. Management: built-in holds, pre-written launch commit criteria, and automated terminal counts.
19 — $1\ \text{Mbit/s} \times 300\ \text{s} = 300\ \text{Mbit} = 37.5\ \text{MB}$. If it makes more than that between passes, it must store data onboard and replay it (store-and-forward), or obtain more/longer passes.
20 — Control shifts from real-time steering (LEO) to sending time-tagged sequences and trusting the vehicle (deep space); onboard autonomy and fault protection become mandatory because the ground is always at least one light-time away.

Topics to review by question

Questions Topic Section
1, 8, 13 Mission-control roles §31.2
2, 3, 10, 14 Telemetry and commanding §31.4
4, 5, 6, 7, 16, 20 Communication latency and autonomy §31.5
9 Anomaly resolution §31.4
11, 17 Flight dynamics and contact windows §31.3
12, 18 Launch operations and integration §31.1
15, 19 LEO contact windows / data volume §31.3, §31.5