MAV Ascent Modification

Lore & Background

The MAV Ascent Modification was born from cold, hard arithmetic. After the dust storm stranded him, Watney ran the orbital mechanics and discovered a brutal truth: the MAV, designed to lob four astronauts into a low parking orbit, lacked the delta-v to catch the Hermes as it whipped past Mars on a gravity-assist slingshot. The Hermes would be moving faster and riding a higher, more energetic trajectory. To close the gap, Watney had to turn the MAV into a flying skeleton. He ripped out every seat, every panel, the entire nose cone—anything that wasn't structural or fuel. He even devised a hair-raising burn sequence that would push the hydrazine-fed engines past their rated limits, essentially hot-rodding the rocket by over-pressurizing the fuel lines. It was a plan that would have made any NASA engineer blanch, but it was the only shot he had.

Reader's Guide

The MAV Ascent Modification unfolds in several key stages. First, Watney realizes the MAV's original trajectory cannot match the Hermes' orbit, prompting a complete redesign of the launch plan. He calculates the necessary delta-v and determines that weight reduction is essential. He removes all non-essential items from the MAV, including seats, panels, and the nose cone, and even uses a technique to vent excess pressure from the fuel tanks to increase thrust.

Next, he modifies the launch sequence to include a 'slingshot' maneuver, using the MAV's remaining fuel in a series of burns that push the vehicle beyond its designed limits. The launch itself is a tense, high-risk event, with Watney enduring extreme G-forces and potential structural failure. The modification's success allows him to achieve a trajectory that intercepts the Hermes, where Commander Lewis performs a daring EVA to retrieve him. The impact of this modification is monumental: it enables Watney's rescue, proving that human ingenuity and adaptability can overcome seemingly impossible odds.

Did You Know?

• Watney had to remove the nose cap of the MAV and cover it with Hab canvas to reduce weight.
• The MAV was originally pre-positioned for the Ares 4 mission, which would land in four years.
• After takeoff, the canvas tore, creating extra drag and leaving the MAV too low for the rendezvous.
• Lewis improvised a plan to intercept the MAV by firing Hermes' attitude thrusters and blowing a hole in the front airlock with an improvised sugar-and-liquid-oxygen bomb.
• Beck used a Manned Maneuvering Unit on a tether to reach Watney and bring him back to Hermes.