Venkat’s phone rang in the middle of a paragraph, as it usually did. Venkat’s time was generally divided between reading reports (or, not nearly often enough, papers exploring the theoretical possibilities of magic, if humans could ever get it to work) and writing letters thanking, pleading, or ordering somebody to do something on behalf of Project Ares. It was all important, but no matter how important it was, there were dozens of people with his office phone number who thought their issues were more important. A few of them were even correct.
He checked the caller ID. Bruce Ng. Well, Bruce never wasted Venkat’s time with trivialities. Bruce never had any time of his own to waste.
“Hello, Bruce,” he said as soon as he picked up the line. “And how are things in sunny California?”
“I know there’s a sun in theory,” Bruce said. “Not by direct observation. I’ve been working for over a month to find some way to make the MAV landing stage work as a booster. I’m calling you to tell you it can’t be done.”
Venkat leaned back in his chair. “I’m listening,” he said. “Tell me why a step that’s absolutely indispensable to Mark Watney and friends making a direct rendezvous with Hermes is impossible.”
“It comes down to weight and timing,” Bruce said. “The whole point of keeping the landing stage on and running the pony engines on it is to gain surplus delta-V to make up for the weight we can’t shave off the MAV. We’d need to reduce a craft that weighs twelve and a half tons empty by over five tons to achieve escape velocity on internal power alone. We haven’t been able to find more than two tons without taking steps that render the MAV nonviable for long-term habitation- that is, we have to put a hole in the hull to make it lighter. That would take away the Sparkle Drive option as a backup system.”
“Yes, I understand all that,” Venkat said. “But that’s what the landing stage and the engines off of Friendship were meant to overcome.”
“And we’ve tried it in every configuration possible,” Bruce said. “We’ve tried launching it fully fueled, on the assumption that the ponies can find a way to transmute or synthesize hydrazine. We’ve tried ripping out absolutely everything and just using the descent stage as a framework to hang the pony engines on. And, of course, we asked Starlight Glimmer to make larger batteries that could run the engines for a full three-minute burn instead of the one minute we originally planned.
“But it all fails in the sims, Venkat. Nothing we try gets more than a thrust-weight ratio of 1.3. A three minute burn just barely gets the ship to the height of the Schiaparelli Basin rim, when you factor in gravity and air resistance. The sims routinely show a failure rate of fifteen percent attempting to decouple the landing stage, ignite the first ascent stage, and reorient the craft. And by failure, I mean surface impact before the procedure’s complete. And even the eighty-five percent of successful flights yield only an average delta-V gain of two hundred meters per second. That’s out of over five kilometers per second we need.”
“Okay,” Venkat said. “So what happens when you move the pony engines to the first ascent stage?”
“No improvement,” Bruce said. “Without any way to decouple the engines and their batteries, they stay on as dead weight after they burn out. If we cut the pony engines to fifty percent thrust we might be able to stretch them through the whole first stage burn, but the efficiency losses mean they don’t quite get us to where we need to be. And we lose the most efficient portion of the ascent burn to that added eight tons of engine and batteries.”
“Bruce,” Venkat said, marshaling his thoughts carefully, “I don’t need to tell you how bad this news is. You know better than anyone. But I’m not hearing much in the way of potential solutions.”
“We’re… still working on it,” Bruce said. “But we’re at the point that we need some input from the ponies. Is there any way to lighten their engines, or to modify them so they produce more thrust faster? And I know we’ve turned off the email exchange, but I wanted to ask for a waiver so I could send them the work we’ve done so far through Pathfinder.”
For a second Venkat lost the power of speech. When he recovered it, it still spluttered like a car with a bad injector. “Wha-bwuh-wha… Bruce, you are two thousand miles closer to the Pathfinder relay than I am. You have a team who knows intimately the problems we’re having just getting a signal. The data stream’s been getting parity check errors on data packets for the last two days. You know why we decided to shut down everything but the bare bones. And if you thought we could still send your data, you wouldn’t ask me for confirmation. You'd just do it.”
Venkat heard Bruce’s sigh over the line. “I know,” he said. “And you’re right, we can’t load up the link with a ton of data when it’s barely good enough for emergencies. But the alternative is that we lose more than a month. A month in which we could work the problem.”
“Well, continue working it from your end,” Venkat said. “I’ll try to drop the problem into the morning check-in, but no promises.”
“Thanks,” Bruce said, and cut the connection.