Margaritifer Basin (Margaritifer Trilogy Book 1)

by Gregory Gates

  “Wait a minute… the Rocket Equation says I can. It’s obviously not accurate down to the meter per second and pound, but it’s in the ballpark, and shows about 16% to spare.”

  “Yes, but there is a wee problem with your math.”

  “I didn’t do the math, the computer did.”

  “Yes, but garbage in, garbage out. Your numbers are correct, but only if the booster is fueled with LH2 and LOX, not if it’s fueled with N2O4 and Aerozine-50. You used the wrong exhaust velocity. You’re short by a thousand meters per second.”

  He slapped his forehead. “Holy shit! Are you kidding me?”

  “Sorry, no. You’re going to need a much bigger booster. And you can’t rely on the service module SPS, because you’ll need its remaining life and fuel for mid-course corrections and re-entry alignment. So the booster will have to do the entire job of getting us into Trans-Earth Injection.”

  “How much bigger?”

  “Oh, I don’t know, at least twice the size of what you had in mind.”

  “Twice?”

  “Yes. Off the top of my head, I’d say somewhere in the neighborhood of 115,000 pounds of fuel, and even that is with certain qualifications.”

  “What kind of qualifications.”

  “Well, first I would suggest using a different fuel.”

  “What?”

  “RP-1 and LOX. It gives you a better exhaust velocity, it’s cheaper, and all you need to do is figure out how to keep the RP-1 from freezing for two years. Further, it’s in wide use and there’s probably an available rocket stage out there somewhere that will come very close to what we need. If nothing else, we could probably talk with SpaceX about having them construct a Merlin-based stage to do the job.”

  Jeff shrugged. “Okay, that doesn’t sound so bad.”

  Gabe smiled. “No, except that still doesn’t get us there. We need a lower Delta-V.”

  “Um, I didn’t think Delta-V had a dial adjustment.”

  “Well, it does in a sense.”

  “What?”

  “Change the return trip dates.”

  “To what?”

  “I see why you picked those dates; it gives us the longest stay on Mars and a comparatively short, 179-day, return transit – for which I’m sure we would all be appreciative when the time comes. However, as I said, that transit calls for a Delta-V of 3,280 meters per second. For that, you’ll need a booster the size of an S-IVB. So, what I propose is instead of departing on May 6th, we leave on March 14th for a 212-day transit, arriving home on October 12th, instead of November 1st. Okay, yes, we’ll have to spend an additional 33 days in space but, on the other hand, we will get home two weeks earlier, not to mention spending a month and a half less on Mars. But, out of a year and a half stay, that’s probably not statistically significant. And, that transit only requires a 2,468 meter per second Delta-V, which is much easier to achieve.”

  “You sure?”

  Gabe canted her head and glared at him.

  “Sorry. Alright, so with your super-sized Centaur and date change, we can make it home?”

  “Yes, assuming we can figure out how to get the thing to Mars in the first place.”

  “Um, 115,000 is within a Falcon Heavy’s payload to LEO, and it’s no challenge at all for an EDS to put that mass into TMI. What’s the problem?”

  “Getting it into orbit around Mars.”

  Jeff frowned. “We use an aerocapture. We’ve already talked about that.”

  “Yes, we have. But we have not talked about attempting to aerocapture nearly 60 tons. I’m not the least bit convinced that’s even possible. For starters, you’ll have to dip it so far into the atmosphere it’ll probably be kicking up sand as it goes by. Second, even if you can capture it into orbit, that orbit is going to by utterly awful. We’ll never be able to get to it.”

  He sighed aloud and rubbed his forehead. “Okay, so then we aerobrake into a better orbit.”

  Gabe shook her head. “Jeff, it took the MRO five months to aerobrake into its final orbit. We won’t have months, we’ll have days; two weeks at best.”

  Jeff groaned. “Oh, fuck me.”

  Gabe frowned. “Uh, no, I don’t think so.”

  “Sorry, figure of speech.”

  “I’d prefer you used a different one.”

  Jeff rolled his eyes. “I stand admonished. Okay, so we need to do a powered insertion.”

  Gabe shrugged.

  “Can we send a second booster along with it? Or just make that one bigger?”

  “It would have to be twice the size, or you’d need a second booster of equal size.”

  “Oh god.”

  “Yes. Um, that would require another launch, another Falcon Heavy. But there’s an even bigger problem; now you’re up to 230,000 pounds, minimum. Add to that 32,500 pounds for the burnout mass of the EDS and… you can’t get there from here. You’d need 300,000 pounds of fuel for the TMI, and you don’t have it. At most you have 260,000.”

  “Ah Jesus! Gabe, there has to be a way to get home.”

  Gabe smiled. “Jeff, it’s obvious that you’ve read most of the various manned Mars proposals that are floating around. And, as such, you’ve probably noticed that many of them concluded with something like ‘And we leave Mars and go home’, footnote: details to follow. Getting to Mars is easy; it’s been done lots of times. Landing stuff on Mars is not that hard; that’s also been done many times. But getting back from Mars? That’s never been done, and for good reason. That is the hard part. That, to use your expression, is the part for which there is no part. And I don’t know about you, but if we can’t get back, I’d rather prefer not to go.”

  Jeff nodded. “Well, I won’t argue that. I’ve read a couple of the suicide mission proposals.” He shook his head. “There are some seriously demented people out there.”

  “Yes, and I’d rather not be one of them.”

  “Yeah, now I understand why there’s so much talk of in situ manufacture of the return trip fuel.”

  “Correct, but that too is not without its problems, not the least of which is, how do you get all that fuel off Mars and into orbit?”

  “Just out of idle curiosity, what would it take to launch 115,000 pounds from Mars?”

  “I don’t know, there are a lot of variables and unknowns. Um, but just using a ballpark figure of say, orbital velocity at 100 miles in altitude, and ignoring gravity and air resistance, you’re looking at a minimum Delta-V of, um, about 3,460 meters per second. That would take another 260,000 pounds of fuel. So, I don’t know, call it 300,000, minimum, plus payload.”

  “Good god, that’d take forever to manufacture.”

  “Yes, you’d have to launch everything for in situ in this next launch window.”

  “Can’t be done.”

  “No.”

  “Anything left in the cupboard?”

  “It’s looking rather bare. There’s just not enough time.”

  “Son of a bitch, there has to be a way to do this.”

  Gabe smiled. “You know, I think you’re spending too much time around Abby. You’re starting to talk like her.”

  “Sorry.” Jeff stared at all the drawings on the walls and thought for a moment. “Hey, what if we put the return booster in a lifting body, so we have more control of it during the aerocapture? And, I might add, by that time we will have already had some experience with lifting bodies in Mars atmosphere. At least the first cargo ship, maybe both.”

  Gabe’s eyebrows went up. “Hmmm, that could work, though you still have the problem of trimming the orbit.”

  “Okay, um, how about we split the difference.”

  “Huh?”

  “We send along a second booster about the size of a Centaur. Then, once it’s captured we jettison the aeroshell and heat shield and use the Centaur to trim the orbit, quickly. Could we get that mass to Mars?”

  She slowly nodded. “Yes.” She smiled. “That might just work. It’d still require another launch, but just of the Centaur.
You could do that with an Atlas V.”

  “Uh huh.” Jeff sat back in his chair and sighed deeply. “Work on it. That may just be our answer.”

  “Okay. But, there’s still the matter of fuel for the SPS. Oh, and also the lander.”

  “What are we talking, about 20,000 pounds?”

  “Yes.”

  “Well, we might be able to squeeze that into a Delta IV Heavy and do it in one shot.”

  “You’ll also need a cruise stage that’s big enough to get it into orbit.”

  “Oh crap, there’s no end to this. Alright, well, juggle all the manifests and see if there isn’t some way that we can squeeze that stuff, or at least part of it, in somewhere else. We have to have some spare payload somewhere. Work on it.”

  “Okay.”

  Jeff stared at the table and thought for a moment. “Um, there is one other problem with this scenario.”

  “What?”

  “Well, assuming we follow through with our plan to bring home a real live Martian, and a minimum of six months development time in gravity, that date change cuts our window for conception down to two and a half months. That’s not a whole lot of time.”

  Gabe frowned. “Jeff, I’m a physicist, not an obstetrician or pediatrician. I can tell you how to get us there and maybe how to get us back, but what you’re talking about is way outside my field. Besides, you know full well that I’m not real crazy about the idea to begin with. I’ll go along with it, I’ve told you that, and I mean it, even if the, uh, chosen one turns out to be me.” She grimaced and swallowed hard. “But, don’t look to me for solutions on that matter.”

  Jeff smiled apologetically, and nodded. He reached across the table and took her hand. “Yeah, sorry, you’re right.”

  She nodded.

  “Okay, you just go right on catching my mistakes, and we’ll be fine.”

  “I’ll try.”

  “What were those dates again?”

  “March 14, October 12.”

  “Alright, get those to Chrissie and have her adjust the flight plan accordingly. We’ll probably have to bump something from the surface exploration plan but what the hell, it’s probably too ambitious anyway. And, as you note, just getting there and back is the important part.”

  She squeezed his hand. “You’ll get no argument from me on that.”

  “And in the meantime, find us a return booster. That could be a long lead-time item, so we’ll need to get it started soon.”

  Gabe nodded. “Right.”

  Jeff gazed into her eyes and smiled softly. “Now do you know why you’re here?”

  She returned the smile and nodded. “Yes.”

  “Think you’d be doing this in some post-doc research job at Caltech?”

  Gabe shook her head. “No.”

  “Okay then. Are we done?”

  “Not quite.”

  Jeff groaned, “Oh god, what else?”

  “After this first series of launches, you’ll be broke. What are we gonna do?”

  Jeff smiled. “Raise more money. Like launch weights and Delta-Vs, there’s no other option.”

  Gabe smiled and nodded.

  Abby’s voice rang out from the theater in Wrentham House’ lower level, “Would you two give it a rest and get in here? We’re supposed to be having a party.”

  Gabe frowned, “What is she yakking about now?”

  “I dunno.” Jeff yelled back, “On our way.”

  “The big day,” said Gabe as she and Jeff walked toward the theater.

  Jeff shook his head, “God I hope it works. Everything depends on it.”

  She took his hand and squeezed it, “It’ll work.”

  #

  Eight and a half months earlier NASA had finally managed to get the Mars Science Laboratory, Curiosity, off the ground and on its way to Mars. It was now just a couple hours from landing. Jeff’s entire plan depended upon utilizing the MSL’s Entry, Descent and Landing – or EDL – technology. If the MSL failed to make it to the surface in one piece, Jeff’s dream of going to Mars might well be over.

  It was shortly past 10:30 when Jeff stepped into the dimly lit theater and looked up at the twelve-foot screen. “Nice picture.” The entire screen was filled with a close-up view of Mars’ southern hemisphere. It was late afternoon on the red planet, and the surface features were clear and bright. “What are we looking at?”

  Abby looked at him a bit flabbergasted, “It’s Mars, doofus!”

  “Really? You sure?” He gave her a mildly sarcastic grin. “Chrissie, what is this?”

  Chrissie glanced up from the console at the back of the theater. “Time lapse of Viking II’s approach to Mars. There’s no feed yet from JPL. They’ll begin their live stream in about an hour. I think the MRO will be in a position to see the MSL landing. That’d sure look cool on the HiRISE camera.”

  “That it would.”

  Gabe nodded. “The HiRISE got a shot of the Phoenix lander on chute, they should be able to get this one, maybe. They timed it about right. The MRO is in a polar orbit and makes exactly twelve sun-synchronous orbits a day – Mars time. And on the daylight side it always crosses the equator at exactly 3:00 p.m. LMST – Local Mean Standard Time – which is almost exactly when the MSL is scheduled to land.”

  Susan walked up to them with a couple mugs. “Coffee? It’s fresh.”

  Jeff took a mug. “Yeah, thanks.”

  “And there’s a bunch of food on the table. I also put some champagne on ice, just in case.”

  “Hey, that’s great. Thanks. The power of positive thinking?”

  Susan laughed, “Something like that. Those images aren’t from the MSL?”

  Gabe shook her head. “No. The MSL doesn’t have a camera on the aeroshell. The first MSL images we should see will probably be from the hazard avoidance cameras, Hazcams, shortly after landing. They are small black and white cameras that are mounted over the wheels. It’ll probably be tomorrow before we see the first images from the MARDI.”

  “What’s the MARDI?”

  “Mars Descent Imager. It’s a down looking color camera located beneath the rover that will start taking pictures at about eight frames per second as soon as the heat shield is jettisoned. They’ll use its pictures to figure out where it lands.”

  “They don’t know where it’s going to land?”

  “Oh, they know within 10 kilometers or so. But in comparing the MARDI images with images of the area from the MRO’s HiRISE camera they’ll be able to pinpoint its location. And they need that in order to tell it where to go and what to do with itself. But that’s also why they would like to image it with the HiRISE as quickly as possible. That will also tell them right where it is.”

  “How will they manage to have the MRO taking pictures of the landing? Can they adjust its orbit?”

  “Yes, but they probably didn’t need to, they just adjusted the MSL’s trajectory to schedule a landing when the MRO would be making a pass over the landing site.”

  “And that will be what time here?”

  “The landing is scheduled for 2:50 p.m. LMST, a little less than three hours from now, though it will be another fourteen minutes before we see it, about 1:32”

  “Is that when we plan on landing? Mid-afternoon?”

  Jeff shook his head. “Wouldn’t be my first choice. We’re going to have a lot of work ahead of us immediately upon arrival. It’ll be a long day. An early to mid-morning arrival would give us a lot more daylight to get some things done.”

  “Like what?”

  “Well, the rovers will be able to relocate some things and even make some simple connections, like electrical and various tank connections to the Sabatier reactor, but they won’t be able to dock the habs, since the docking adapters will have to be unpacked; we’ll have to do that ourselves. Further, most of our provisions won’t be on wheels, and we’ll have to locate those and manually winch them onto the rovers and haul them to the station. We can temporarily setup housekeeping in the Genesis trailer, but it�
��s only fourteen feet long and eight feet in diameter, not including the air lock, so it’s a bit cozy for four. The sooner we can get the station assembled, the more comfortable we’ll be. So the first few days will likely be pretty busy.”

  “Sounds like it.” Susan frowned. “Does the trailer have a bathroom?”

  Jeff grinned. “Um, define… bathroom.”

  “Uh oh.”

  “Yeah, it has, uh, facilities, but not exactly a, um… bathroom.” He chuckled. “Eh, it’ll just inspire y’all to work a little faster. Chrissie, where’s the MSL?”

  “5,430 meters per second, about 48,900 kilometers altitude, two and a half hours to go. Five by five and in the pipe,” she grinned.

  Jeff glanced back at her and winked, “Now you sound like an astronaut.”

  Chrissie smiled broadly and gave him a thumb up.

  Gabe stood next to Jeff, looking up at the screen. “Wow. Just think, if all goes well four years from now we’ll be seeing that view out the front window.”

  “Yeah, that will be something. Chrissie, what’s the time delay?”

  “I don’t know. Right now Mars is, um, let me see, 1.66 AUs from Earth, so…”

  “13.8 minutes,” said Gabe.

  Chrissie shook her head and muttered, “How does she do that?”

  Jeff glanced at Gabe and smiled.

  She shrugged.

  “I hope the MRO is still working when we’re up there, or some replacement. Otherwise, we may have to put our own eyes in orbit.”

  “I wouldn’t count on the MRO for much longer,” said Gabe. “It was designed for a two-year mission, it’s already been up there for six.”

  “How far is the MSL landing site from where we’re going?” said Susan.

  “Oh, about as far away as you can get and still be on Mars,” said Jeff. “It’s on the other side of the planet. Here, I’ll show you. Chrissie, give me a split screen and bring up that USGS Mars regional map, the pdf one.”

  “Okay, just a second.”

  “Our landing site in the Margaritifer Basin is roughly 14° South, 338.3° East. The MSL is headed for a spot in Gale Crater at around 5.4° South, 137.8° East. That’s about, um, I dunno…” He glanced at Gabe.