Author's Note: I've known for a while that I would build the Nautilus after building the Vigilance, and that the ship would be the one that becomes lost in Contact Lost. I based the design after the NAUTILUS-X study that NASA created and named the ship after NASA's design as well. She went through fewer design iterations that Vigilance since I had most of the parts that I needed, and all I had to do was combine them into a ship that I liked. As always, this is a work of fiction.

Nautilus (DSEV-2)

After the successful mission to the far side of the Moon to explore an Ancient Astronaut pyramid dubbed The Observatory, the world gained new technologies that opened up the Solar System to exploration. While it took years for space probes like Voyager and Pioneer to reach the outer planets, ships using the new technology, dubbed Black Box Technology (BB Tech) in the west, could make the same trip in a matter of weeks. How the Ancient Astronauts- humans, not aliens- created BB Tech remains a mystery. But while Vigilance (DSEV-1) demonstrated BB Tech's potential, the National Aerospace eXploration Administration's (NAXA) Nautilus (DSEV-2), the second Deep Space Exploration Vessel, was built to solve the mystery. She was named after the submarine from Jules Verne's Twenty Thousand Leagues Under the Sea as well as for the world's first nuclear powered submarine. In a naming competition, Nautilus barely beat out Enterprise, and a write-in campaign failed to change the ship's name.

While a few components came from leftovers created for Vigilance, Nautilus had a number of new components including her mini-magnetosphere generator and her keel modules capped with Structurally Reinforced Berthing Mechanisms (SRBMs). These components helped DSEV-2 overcome some of her predecessor's design limitations. Her enlarged science labs, larger storage modules and increased fuel capacity gave Nautilus greater endurance for conducting more in-depth research. She could even deploy a field lab for an up close study of an airless celestial body, and had a constellation of reusable Navigation and Reconnaissance /Communications Satellites (NARCS) to support ground operations on an interesting moon.

Completed in early 2018, Nautilus was NAXA's flagship for detailed exploration of the solar system. She was also political leverage for NAXA to become America's premier space exploration agency. While the 2015 Military Space Act cemented the Air Force's role as defenders of America's space interests, NAXA wanted to push them out of the deep space exploration missions that they were conducting with Vigilance. It remains to be seen whether NAXA will be the only ones to go boldly where none have gone before, with the military just providing support. Unfortunately, that vision is currently in jeopardy. NAXA lost contact with Nautilus on May 4th, 2018, as she prepared to leave Saturn's orbit and skip over to Uranus.

Design and Construction

Though successful at demonstrating BB Tech, Vigilance had a number of limitations. Her limited fuel supply enabled her to reach Mars at best, and she had to use engine thrust to slow down to attain orbit. The driveshaft of her skip drive had to be routed through the main hatch of each module's Androgynous Berthing Mechanism (ABM) or Low-Impact Module Berthing System (LIMBS) ports. There was barely any room for crew to squeeze through the hatches, and in the event of a keel module being perforated, there was no way to close the hatches. The ship had limited science capability other than "flags and footprints" missions. Finally, while the habitat modules, command module, GNC module, and core module all had radiation shielding, other areas of the ship weren't well protected. The Nautilus addressed all of these issues and more. The modules described below reflect NAXA's solutions to Vigilance's design problems.

Like Vigilance, Nautilus had to be assembled from various modules launched into orbit using a variety of vehicles including the National Launch System (NLS), Appaloosa (A131), and Shuttle II. Unlike her predecessor though, NAXA laid the "keel" of DSEV-2 at the International Space Station (ISS). Once Nautilus acquired its keel and command and control modules, she cast off from the ISS and flew in formation nearby for the remainder of her construction to avoid disturbing sensitive experiments going on at the station.

Keel Modules

Like the keel of a ship, DSEV-2's keel modules serve as the backbone and foundation for the rest of the ship's construction.  With the exception of the Thermodynamic Fusion Engine, each keel module is capped with an SRBM. Essentially an enlarged ABM, the SRBM has a module berthing ring that is 14 feet in diameter. Structural reinforcement attachment points ring the inner circumference of the berthing ring along with gas and fluid connector pipes. The SRBM hosts a small section of the space-time skip drive's driveshaft via a dedicated sealed port in the berthing mechanism's center, and sports a standard 55" space station hatch above the dedicated port. This arrangement enables a keel module to be sealed in the event of a breach.

Listed below are the ship's keel modules, along with the vehicle(s) that delivered them.

Connector Modules (Shuttle II)

Forming most of the ship's keel, connector modules are the size of a school bus and contain eight LIMBS ports. The ports enable the ship to be modularly configured throughout its lifetime.

Space-Time Skip Drive Module (SLS)

This module houses the BB Tech machinery used by the space-time skip drive, popularly mislabeled as a "warp drive" by the public media. The machinery is virtually identical to its counterpart in DSEV-1. In addition, the module hosts the ship's Plasma And Radiation Deflector Shield (PARDS). PARDS is a new BB Tech application that generates a mini-magnetosphere and inflates it using helium created by the ship's fusion reactor. Like Earth's magnetosphere, PARDS' mini-magnetosphere surrounds the ship and protects it from radiation. Additionally, it shields the ship from plasma generated by atmospheric entry, eliminating the need for traditional heat shield technology. While Nautilus is not designed to land, it can perform an aerobraking maneuver to slow the ship down without using fuel. Finally, PARDS can act as a magnetic sail in the event that the ship loses engine thrust, although its acceleration is very low (0.001g).

Centrifugal Hub Module (Shuttle II)

This NAXA-built module is a design modified from the Vigilance's module of the same name. Other than the SRBMS on the ends, it is virtually unchanged.

Fuel Module (Shuttle II)

This module provides a structural strong back for the ship’s main fuel tanks. As with Vigilance, Nautilus uses ordinary water as its reaction mass as well as hydrogen for the fusion reactor and oxygen for the crew. This module provides the cracking equipment to turn water into hydrogen and oxygen. Six tanks surrounding the module hold the ship’s main water supply.

Thermodynamic Fusion Engine Module (SLS)

Nautilus's engine module was originally the backup engine for Vigilance. After DSEV-1's successful completion, NAXA modified the module to include two additional Timber Wolf motors in order to improve DSEV-2's acceleration. Each engine produces 36,000 pounds of thrust, for a total of 144,000 lbf.

Space-Time Skip Field Emitter (RABBIT)

When Vigilance traveled to Mars, her crew built several skip field emitters and drive shafts before returning to Earth. The Air Force transferred one of the skip field emitters to Nautilus.

Command and Control Modules (Shuttle II)

These modules come straight from the Vigilance construction project and served as backups or test articles until no longer needed. They are unchanged from DSEV-1 with the exception of the Reaction Control System (RCS) Modules, which now have additional thruster ports to compensate for DSEV-2's increased mass. These modules include the Command Module, Guidance, Navigation and Control Module, as well as four RCS Modules situated at the end of NAXA-built truss assemblies.

Habitat Section (A131, Shuttle II)

Nautilus provides improved crew comfort over its predecessor by adding two additional rotary arms and habitat modules, for a total of four rotary arms and four Homestead Commercial Space Modules (CSM). In fact, NAXA tied up Wild Blue Industries Homestead production capacity for several years- Nautilus has fourteen Homesteads configured for various purposes. In addition to the additional habitats, the section spins slower- 4 rotations per minute versus Vigilance's 6 RPMs. While only generating 0.5g, it's much easier to adapt to the section's Coriolis Effect than it is to adapt to DSEV-1's habitat section. Shuttle IIs delivered the rotary arms, while Appaloosas gave the CSMs a ride uphill.

Counter-Spin Section (NLS)

As with DSEV-1, water tanks provide counter-torque for the ship's habitat section. On Vigilance they would be the ship’s main water supply, but on Nautilus, they also serve as auxiliary tanks.

Lab Section (A131, Shuttle II)

Just aft of the Counter-Spin Section and mounted vertically on the keel, the Lab Section consists of four Homestead CSMs configured for laboratory space. One lab module houses the ship's computer core, while its opposite number is used as the NARCS satellite operations center and radio astronomy lab. The ops center/radio astronomy lab sports a radio telescope, and the computer lab is equipped with a laser communications module.

Satellite and Probe Hangars (SLS, Shuttle II)

Just aft of the Lab Section and also mounted vertically are two hangars used to house the NARCS constellation as well as expendable space probes. The satellites and probes are mounted on rotary launchers for easy storage and deployment.

Storage Section (A131, Shuttle II)

DSEV-2's keel is flanked by a half-dozen Homestead CSMs configured for storage. There is ample room to store a wide variety of supplies and materials for spare parts that can be 3D printed on demand. The ship's ice mining equipment is housed here as well.

Docking Section (NLS, Shuttle II)

Not strictly a docking section, Connector Module 3 is used to dock auxiliary spacecraft such as Odyssey, the ship's Mars Excursion Vehicle (MEV), a pair of RABBITS, and the ship's portable field lab (three Twenty-foot Equivalent Modules (TEM) and a Node outfitted with life support and lab equipment). The ship's Space Station Remote Manipulator System (SSRMS) and the ship's Docking Airlock Module reside here as well.