Self-Assessment Quiz: A Mission to Mars

Twenty questions on the launch window, trans-Mars injection, the cruise, EDL, ISRU and the return problem, and the human Mars architectures. Answer each before opening the key. Aim for 16 or more.

Question 1

Mars launch opportunities recur about every:

A) 6 months B) 12 months C) 26 months D) 10 years

Question 2

The trans-Mars injection (TMI) is the burn that:

A) circularizes the spacecraft into low Mars orbit B) raises a low Earth parking orbit onto the Earth-to-Mars transfer trajectory C) lands the spacecraft on Mars D) launches the crew off the Martian surface

Question 3

For the minimum-energy Earth-to-Mars transfer, the trans-Mars injection burn from low Earth orbit is about:

A) 0.6 km/s B) 3.6 km/s C) 9.4 km/s D) 21.5 km/s

Question 4

A large crewed Starship-class vehicle must be refueled in low Earth orbit before trans-Mars injection because:

A) its engines do not work in vacuum B) it reaches orbit nearly empty of propellant, and the injection needs hundreds of tonnes it cannot also carry up in one launch C) methane boils away during ascent D) the crew needs the extra tanks as radiation shielding

Question 5

A conjunction-class (long-stay) Mars mission lasts roughly:

A) 3 weeks B) 3 months C) 900 days (~2.5 years) D) 10 years

Question 6

The surface stay of a conjunction-class mission is about 500 days because:

A) it takes that long to explore the landing site B) the crew must wait for Earth and Mars to re-phase for the minimum-energy return window C) the ISRU plant needs exactly 500 days to make fuel D) the habitat can only hold 500 days of air

Question 7

The one-way deep-space cruise radiation dose to Mars (~259 days at ~1.8 mSv/day) is roughly:

A) 5 mSv B) 50 mSv C) 0.47 Sv D) 50 Sv

Question 8

The spacecraft reaches the top of Mars's atmosphere moving at about:

A) 2.65 km/s B) 5.6 km/s C) 11 km/s D) 21.5 km/s

Question 9

Mars entry, descent, and landing must be fully autonomous mainly because:

A) astronauts prefer not to be involved B) the communication delay (10–20 min one-way at arrival) is longer than the ~7-minute EDL sequence C) the Deep Space Network is switched off during landing D) radio does not work near Mars

Question 10

Why is Mars EDL harder than landing on the Moon or returning to Earth?

A) Mars has stronger gravity than Earth B) Mars's atmosphere is thick enough to require a heat shield but too thin to stop a heavy vehicle with parachutes C) Mars has no atmosphere at all D) Mars is farther from the Sun

Question 11

A large parachute lands the same capsule at about 17 m/s on Earth but about ____ on Mars:

A) 2 m/s B) 17 m/s (the same) C) 84 m/s D) 500 m/s

Question 12

Aerocapture differs from aerobraking in that aerocapture:

A) uses many shallow passes over weeks B) uses one deep atmospheric pass to capture directly into orbit C) requires no heat shield D) is only used at Earth

Question 13

In-situ resource utilization (ISRU) for a Mars mission most importantly:

A) grows food on the surface B) manufactures return propellant from the Martian atmosphere C) mines metals for construction D) generates electrical power

Question 14

The Sabatier reaction used for Mars ISRU is:

A) $2\text{H}_2\text{O} \rightarrow 2\text{H}_2 + \text{O}_2$ B) $\text{CO}_2 + 4\text{H}_2 \rightarrow \text{CH}_4 + 2\text{H}_2\text{O}$ C) $\text{C}_6\text{H}_{12}\text{O}_6 + 6\text{O}_2 \rightarrow 6\text{CO}_2 + 6\text{H}_2\text{O}$ D) $\text{CO}_2 + 2\text{H}_2 \rightarrow \text{C} + 2\text{H}_2\text{O}$

Question 15

The propellant that Mars ISRU (Sabatier + electrolysis) naturally produces is:

A) hydrolox (LH2/LOX) B) kerolox (RP-1/LOX) C) methalox (CH4/LOX) — the same propellant Starship's Raptor burns D) solid propellant

Question 16 (True/False, justify)

"MOXIE on the Perseverance rover already proved that oxygen can be made from Mars's atmosphere." True or false? Justify in one sentence.

Question 17 (True/False, justify)

"Because the trans-Mars injection is only ~3.6 km/s, it needs very little propellant even for a large crewed ship." True or false? Explain briefly.

Question 18 (True/False, justify)

"NASA's DRA 5.0 and SpaceX's Starship fly fundamentally different trajectories to Mars." True or false? Explain.

Question 19 (Short answer)

Name the two propulsion/architecture choices where DRA 5.0 and Starship most disagree, and say in a phrase what each choice is trying to buy.

Question 20 (Short answer)

In one or two sentences: why is the return propellant the most leverage-heavy mass in a Mars mission, and how does ISRU defeat that leverage?

Answer Key

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