Mars Mission: Exploring the Red Planet

A: Choosing the wrong alloy can mean cracked bolts after thermal cycling, and there’s no EVA to fix it. Trace moisture plus tensile stress makes stress corrosion cracking credible even in a dry environment, especially over long durations. Chloride pitting needs sustained liquid films, hydrogen embrittlement needs active electrochemistry, and abrasion alone doesn’t explain delayed brittle failure.

A: Forcing the machine harder cooks bearings and seals, ending the campaign early. Backing off flow reduces compression work and temperature while staying inside the map. Speeding up worsens fouling effects, venting wastes precious product and risks dust ingress, and higher pressure only raises discharge temperature further.

A: A wrong sensor choice means drifting readings and bad propellant management. A rad-hard MEMS absolute device is built for low pressures and radiation. Mechanical gauges don’t like launch loads, automotive MAP sensors aren’t rated for radiation or vacuum, and a differential device tied to cabin pressure fails once the reference changes.

A: Undersizing the radiator leaves avionics hot-soaked and forces power-downs. Using Q = εσA(T⁴ − Tsink⁴) with space as the reference gives an area around 1.6 m². Smaller areas drop a power of temperature or emissivity, while the larger numbers double-count losses that aren’t there.

A: Chasing software when the hardware is shorted wastes sols you don’t have. A shorted bypass diode collapses current under load while leaving open-circuit voltage looking healthy. Dust and cold reduce both voltage and current, and a controller fault wouldn’t preserve clean open-circuit readings at the array terminals.

A: Picking a soft or crack-prone bit stalls sampling and jeopardizes science return. Tungsten carbide handles abrasion and retains hardness across temperature swings. Coated HSS loses coating quickly, aluminum bronze wears fast, and martensitic stainless trades hardness for corrosion resistance that isn’t needed here.

A: A bad call here leads to hard starts or flameout. Heating maintains vapor pressure without over-pressurizing the system. Dumping more helium risks exceeding MAWP, waiting just lets pressure fall further, and venting throws away what little margin you have.

A: A leaking container invalidates the entire sample set. A metal C-ring tolerates dust, vacuum, and time without creep. Elastomers harden and leak, PTFE lips wear with particulates, and bonded silicone cracks under cycling.

A: Getting this wrong means either bottoming out or carrying dead mass. Energy equals stress times area times stroke, giving 12,000 J / (3×10⁶ Pa × 0.01 m²) ≈ 0.4 m; applying the usual certification margin pushes the required stroke near 0.6 m. The smaller values drop the margin, the largest assumes a safety factor that isn’t justified by test data.