Posted on by Matt Williams

NASA Has Tested a New Fission Space Reactor that Could be Used in Future Missions

Artist's concept of new fission power system on the lunar surface. Credits: NASA

Looking to the future of crewed space exploration, it is clear to NASA and other space agencies that certain technological requirements need to be met. Not only are a new generation of launch vehicles and space capsules needed (like the SLS and Orion spacecraft), but new forms of energy production are needed to ensure that long-duration missions to the Moon, Mars, and other locations in the Solar System can take place.

One possibility that addresses these concerns is Kilopower, a lightweight fission power system that could power robotic missions, bases and exploration missions. In collaboration with the Department of Energy’s National Nuclear Security Administration (NNSA), NASA recently conducted a successful demonstration of a new nuclear reactor power system that could enable long-duration crewed missions to the Moon, Mars, and beyond.

Known as the Kilopower Reactor Using Stirling Technology (KRUSTY) experiment, the technology was unveiled at a recent news conference on Wednesday, May 2nd, at NASA’s Glenn Research Center. According to NASA, this power system is capable of generating up to 10 kilowatts of electrical power – enough power several households continuously for ten years, or an outpost on the Moon or Mars.

NASA and NNSA engineers lower the wall of the vacuum chamber around the Kilowatt Reactor Using Stirling TechnologY (KRUSTY system). Credits: Los Alamos National Laboratory

As Jim Reuter, NASA’s acting associate administrator for the Space Technology Mission Directorate (STMD), explained in a recent NASA press release:

“Safe, efficient and plentiful energy will be the key to future robotic and human exploration. I expect the Kilopower project to be an essential part of lunar and Mars power architectures as they evolve.”

The prototype power system employs a small solid uranium-235 reactor core and passive sodium heat pipes to transfer reactor heat to high-efficiency Stirling engines, which convert the heat to electricity. This power system is ideally suited to locations like the Moon, where power generation using solar arrays is difficult because lunar nights are equivalent to 14 days on Earth.

In addition, many plans for lunar exploration involve building outposts in the permanently-shaded polar regions or in stable underground lava tubes. On Mars, sunshine is more plentiful, but subject to the planet’s diurnal cycle and weather (such as dust storms). This technology could therefore ensure a steady supply of power that is not dependent on intermittent sources like sunlight. As Marc Gibson, the lead Kilopower engineer at Glenn, said:

“Kilopower gives us the ability to do much higher power missions, and to explore the shadowed craters of the Moon. When we start sending astronauts for long stays on the Moon and to other planets, that’s going to require a new class of power that we’ve never needed before.”

Artist’s impression of four KRUSTY generators providing power to an outpost on the surface of Mars. Credit: NASA/STMD

The Kilopower experiment was conducted at the NNSA’s Nevada National Security Site (NNSS) between November and March of 2017. In addition to demonstrating that the system could produce electricity through fission, the purpose of the experiment was also to show that it is stable and safe in any environment. For this reason, the Kilopower team conduct in the experiment in four phases.

The first two phases, which were conducted without power, confirmed that each component in the system functioned properly. For the third phase, the team increased power to heat the core slowly before moving on to phase four, which consisted of a 28-hour, full-power test run. This phase simulated all stages of a mission, which included a reactor startup, ramp up to full power, steady operation and shutdown.

Throughout the experiment, the team simulated various system failures to ensure that the system would keep working – which included power reductions, failed engines and failed heat pipe. Throughout, the KRUSTY generator kept on providing electricity, proving that it can endure whatever space exploration throws at it. As Gibson indicated:

“We put the system through its paces. We understand the reactor very well, and this test proved that the system works the way we designed it to work. No matter what environment we expose it to, the reactor performs very well.”

A Kilopower reactor could allow for permanent bases on the Moon and Mars and allow for the local production of fuel and other materials. Credit: ESA/Foster + Partners

Looking ahead, the Kilopower project will remain a part of NASA’s Game Changing Development (GCD) program. As part of NASA’s Space Technology Mission Directorate (STMD), this program’s goal is to advance space technologies that may lead to entirely new approaches for the Agency’s future space missions. Eventually, the team hopes to make the transition to the Technology Demonstration Mission (TDM) program by 2020.

If all goes well, the KRUSTY reactor could allow for permanent human outposts on the Moon and Mars. It could also offer support to missions that rely on In-situ Resource Utilization (ISRU) to produce hydrazine fuel from local sources of water ice, and building materials from local regolith.

Basically, when robotic missions are mounted to the Moon to 3D print bases out of local regolith, and astronauts begin making regular trips to the Moon to conduct research and experiments (like they do today to the International Space Station), it could be KRUSTY reactors that provide them will all their power needs. In a few decades, the same could be true for Mars and even locations in the outer Solar System.

This reactor system could also pave the way for rockets that rely on nuclear-thermal or nuclear-electric propulsion, enabling missions beyond Earth that are both faster and more cost-effective!

And be sure to enjoy this video of the GCD program, courtesy of NASA 360:

Further Reading: NASA

Posted on by Matt Williams

NASA is Investigating a Self-Assembling Space Telescope

Graphic depiction of Modular Active Self-Assembling Space Telescope Swarms Credit: D. Savransky

NASA has some pretty advanced concepts in mind when it comes to the next generation of space telescopes. These include the Transiting Exoplanet Survey Satellite (TESS), which recently took to space, as well as the James Webb Space Telescope (JWST) (scheduled to launch in 2020) and the Wide-Field Infrared Survey Telescope (WFIRST), which is still in development.

Beyond these, NASA has also identified several promising proposals as part of its 2020 Decadal Survey for Astrophysics. But perhaps the most ambitious concept is one that calls for a space telescope made up of modules that would assemble themselves. This concept was recently selected for Phase I development as part of the 2018 NASA Innovative Advanced Concepts (NIAC) program.

The team behind this concept is led by Dmitri Savransky, an assistant professor of mechanical and aerospace engineering at Cornell University. Along with 15 colleagues from across the US, Savransky has produced a concept for a ~30 meter (100 foot) modular space telescope with adaptive optics. But the real kicker is the fact that it would be made up of a swarm of modules that would assemble themselves autonomously.

On March. 23rd, 16 concepts received a Phase I award as part of the NASA Innovative Advanced Concepts (NIAC) program. Credit: NASA

Prof. Savransky is well-versed in space telescopes and exoplanet hunting, having assisted in the integration and testing of the Gemini Planet Imager – an instrument on the Gemini South Telescope in Chile. He also participated in the planning of the Gemini Planet Imager Exoplanet Survey, which discovered a Jupiter-like planet orbiting 51 Eridani (51 Eridani b) in 2015.

But looking to the future, Prof. Savransky believes that self-assembly is the way to go to create a super telescope. As he and his team described the telescope in their proposal:

“The entire structure of the telescope, including the primary and secondary mirrors, secondary support structure and planar sunshield will be constructed from a single, mass-produced spacecraft module. Each module will be composed of a hexagonal ~1 m diameter spacecraft topped with an edge-to-edge, active mirror assembly.”

These modules would be launched independently and then navigate to the Sun-Earth L2 point using deployable solar sails. These sails will then become the planar telescope sunshield once the modules come together and assemble themselves, without the need for human or robotic assistance. While this may sound radically advanced, it is certainly in keeping with what the NIAC looks for.

“That’s what the NIAC program is,” said Dr. Savransky in recent interview with the Cornell Chronicle. “You pitch these somewhat crazy-sounding ideas, but then try to back them up with a few initial calculations, and then it’s a nine-month project where you’re trying to answer feasibility questions.”

Artist’s concept of the Large Ultraviolet/Optical/Infrared Surveyor (LUVOIR) space telescope. Credits: NASA/GSFC

As part of the 2018 NAIC’s Phase I awards, which were announced on March 30th, the team was awarded $125,000 over a nine month period to conduct these studies. If these are successful, the team will be able to apply for a Phase II award. As Mason Peck, an associate professor of mechanical and aerospace engineering at Cornell and the former chief technology officer at NASA, indicated, Savransky is on the right track with his NIAC proposal:

“As autonomous spacecraft become more common, and as we continue to improve how we build very small spacecraft, it makes a lot of sense to ask Savransky’s question: Is it possible to build a space telescope that can see farther, and better, using only inexpensive small components that self-assemble in orbit?”

The target mission for this concept is the Large Ultraviolet/Optical/Infrared Surveyor (LUVOIR), a proposal that is currently being explored as part of NASA’s 2020 Decadal Survey. As one of two concepts being investigated by NASA’s Goddard Space Flight Center, this mission concept calls for a space telescope with a massive segmented primary mirror that measures about 15 meters (49 feet) in diameter.

Much like the JWST, LUVOIR’s mirror would be made up of adjustable segments that would unfold once it deployed to space. Actuators and motors would actively adjust and align these segments in order to achieve the perfect focus and capture light from faint and distant objects. The primary aim of this mission would be to discover new exoplanets as well as analyze light from those that have already been discovered to asses their atmospheres.

The Hubble Space Telescope on the left has a 2.4 meter mirror and the James Webb Space Telescope has a 6.5 meter mirror. LUVOIR, not shown, will dwarf them both with a massive 15 meter mirror. Image: NASA
The Hubble Space Telescope on the left has a 2.4 meter mirror and the James Webb Space Telescope has a 6.5 meter mirror. LUVOIR, not shown, will dwarf them both with a massive 15 meter mirror. Image: NASA

As Savransky and his colleagues indicated in their proposal, their concept is directly in line with the priorities of the NASA Technology Roadmaps in Science Instruments, Observatories, and Sensor Systems and Robotics and Autonomous Systems. They also state that the architecture is a credible means to construct a giant space telescope, which would not be possible for previous generations of telescopes like Hubble and the JWST.

“James Webb is going to be the largest astrophysical observatory we’ve ever put in space, and it’s incredibly difficult,” he said. “So going up in scale, to 10 meters or 12 meters or potentially even 30 meters, it seems almost impossible to conceive how you would build those telescopes the same way we’ve been building them.”

Having been granted a Phase I award, the team is planning to conduct detailed simulations of how the modules would fly through space and rendezvous with each other to determine how large the solar sails need to be. They also plan to conduct an analysis of the mirror assembly to validate that the modules could achieve the required surface figure once assembled.

As Peck indicated, if successful, Dr. Savransky’s proposal could be a game changer:

“If Professor Savransky proves the feasibility of creating a large space telescope from tiny pieces, he’ll change how we explore space. We’ll be able to afford to see farther, and better than ever – maybe even to the surface of an extrasolar planet.”

On June 5th and 6th, NASA will also be conducting an NIAC Orientation Meeting in Washington D.C., where all the Phase I winners will have a chance to meet and discuss their ideas. Other proposals that received a Phase I award include shape-shifting robots for exploring Titan, lightweight aerial sensors to explore Venus’ atmosphere, flapping-wing swarm robots to explore Mars, a new form of beam propulsion for interstellar missions (similar to Breakthrough Starshot),  a steam-powered robot for ocean worlds, and a self-replicating habitat made from fungus.

You can read more about these concepts, as well as those that were given Phase II award, here.

Further Reading: Cornell Chronicle, NASA

Posted on by Matt Williams

Air-Breathing Electric Thruster Could Keep Satellites in Low Earth Orbit for Years

An ESA-led team has built and fired an electric thruster to ingest scarce air molecules from the top of the atmosphere as propellant, opening the way to satellites flying in very low orbits for years on end. Credit: ESA/Sitael

When it comes to the future of space exploration, one of the greatest challenges is coming up with engines that can maximize performance while also ensuring fuel efficiency. This will not only reduce the cost of individual missions, it will ensure that robotic spacecraft (and even crewed spacecraft) can operate for extended periods of time in space without having to refuel.

In recent years, this challenge has led to some truly innovative concepts, one of which was recently build and tested for the very first time by an ESA team. This engine concept consists of an electric thruster that is capable of “scooping” scarce air molecules from the tops of atmospheres and using them as propellant. This development will open the way for all kinds of satellites that can operate in very low orbits around planets for years at a time.

The concept of an air-breathing thruster (aka. Ram-Electric Propulsion) is relatively simple. In short, the engine works on the same principles as a ramscoop (where interstellar hydrogen is collected to provide fuel) and an ion engine – where collected particles are charged and ejected. Such an engine would do away with onboard propellant by taking in atmospheric molecules as it passed through the top of a planet’s atmosphere.

The test set-up for the air-breathing electric propulsion thruster recently developed by Sitael and QuinteScience in conjunction with the ESA. Credit: ESA/Sitael

The concept was the subject of a study titled “RAM Electric Propulsion for Low Earth Orbit Operation: An ESA Study“, which was presented at the 30th International Electric Propulsion Conference in 2007. The study emphasized how “Low Earth orbit satellites are subject to atmospheric drag and thus their lifetimes are limited with current propulsion technologies by the amount of propellant they can carry to compensate for it.”

The study’s authors also indicated how satellites using high specific impulse electric propulsion would be capable of compensating for drag during low altitude operation for an extended period of time. But as they conclude, such a mission would also be limited to the amount of fuel it could carry. This was certainly the case for the ESA’s Gravity field and steady-state Ocean Circulation Explorer (GOCE) gravity-mapper satellite,

While GOCE remained in orbit of Earth for more than four years and operated at altitudes as low as 250 km (155 mi), its mission ended the moment it exhausted its 40 kg (88 lbs) supply of xenon as propellant. As such, the concept of an electric propulsion system that an utilize atmospheric molecules as propellant has also been investigated. As Dr. Louis Walpot of the ESA explained in an ESA press release:

“This project began with a novel design to scoop up air molecules as propellant from the top of Earth’s atmosphere at around 200 km altitude with a typical speed of 7.8 km/s.”

Diagram illustrated how air-breathing electric propulsion works. Credit: ESA–A. Di Giacomo

To develop this concept, the Italian aerospace company Sitael and the Polish aerospace company QuinteScience teamed up to create a novel intake and thruster design. Whereas QuinteScience built an intake that would collect and compress incoming atmospheric particles, Sitael developed a dual-stage thruster that would charge and accelerate these particles to generate thrust.

The team then ran computer simulations to see how particles would behave across a range of intake options. But in the end, they chose to conduct a practice test to see if the combined intake and thruster would work together or not. To do this, the team tested it in a vacuum chamber at one of Sitael’s test facilities. The chamber simulated an environment at 200 km altitude while a “particle flow generator” provided the oncoming high-speed molecules.

To provide a more complete test and make sure the thruster would function in a low-pressure environment, the team began by igniting it with xenon-propellant. As Dr. Walpot explained:

“Instead of simply measuring the resulting density at the collector to check the intake design, we decided to attach an electric thruster. In this way, we proved that we could indeed collect and compress the air molecules to a level where thruster ignition could take place, and measure the actual thrust. At first we checked our thruster could be ignited repeatedly with xenon gathered from the particle beam generator.”

Fired at first using standard xenon propellant, the test thruster was then shifted to atmospheric air, proving the principle of air-breathing electric propulsion. Credit: ESA

As a next step, the team partially replace xenon with a nitrogen-oxygen air mixture to simulate Earth’s upper atmosphere. As hoped, the engine kept firing, and the only thing that changed was the color of the thrust.

“When the xenon-based blue color of the engine plume changed to purple, we knew we’d succeeded,” said Dr. Walpot. “The system was finally ignited repeatedly solely with atmospheric propellant to prove the concept’s feasibility. This result means air-breathing electric propulsion is no longer simply a theory but a tangible, working concept, ready to be developed, to serve one day as the basis of a new class of missions.”

The development of air-breathing electric thrusters could allow for an entirely new class of satellite that could operate with the fringes of Mars’, Titan’s and other bodies atmospheres for years at a time. With this kind of operational lifespan, these satellites could gather volumes of data on these bodies’ meteorological conditions, seasonal changes, and the history of their climates.

Such satellites would also be very useful when it comes to observing Earth. Since they would be able to operate at lower altitudes than previous missions, and would not be limited by the amount of propellant they could carry, satellites equipped with air-breathing thrusters could operate for extended periods of time. As a result, they could offer more in-depth analyses on Climate Change, and monitor meteorological patterns, geological changes, and natural disasters more closely.

Further Reading: ESA

Posted on by Matt Williams

Space Catapult Startup SpinLaunch has Come Out of Stealth Mode. Space catapults? Yes Please

SpinLaunch's company hangar. Credit: SpinLaunch

Of all challenges presented by space exploration – and to be fair, there are many! – one of the greatest is the cost. When it comes right down to it, launching disposable rockets from Earth and getting them to the point where they can achieve escape velocity and reach space is expensive. In addition, these rockets need to be big, powerful and hold a lot of fuel to lift spacecraft or cargo.

For this reason, so many efforts in the past few decades have been focused on reducing the cost of individual launches. There are many ways to make launch vehicles cheaper, ranging from reusable rockets to reusable spacecraft (i.e., the Space Shuttle). But to Jonathan Yaney, the founder of SpinLaunch, a real cost-cutting solution is to propel smaller payloads into orbit using a space catapult instead.

The concept of a space catapult is simple and has been explored at length since the dawn of the Space Age. Also known as a mass driver or coilgun, the concept relies on a set of powerful electromagnetic rails to accelerate spacecraft or payloads to escape velocity and launch them horizontally. Since the 1960s, NASA has been exploring the concept as an alternative to conducting rocket launches.

The Magnetic Levitation (MagLev) System is being evaluated at NASA’s Marshall Space Flight Center. Credit: NASA

In addition, NASA has continued developing this technology through the Marshall Space Flight Center and the Kennedy Space Center. Here, engineers have been working on ways to launch spacecraft horizontally using scramjets on an electrified track or gas-powered sled. A good example of this is the Magnetic Levitation (MagLev) System which uses the same technology as a maglev train to accelerate a small space plane into orbit.

Another variation on the concept involves a centrifuge, where the spacecraft or cargo is accelerated on a circular track until it reaches escape velocity (and then launches). This concept was proposed by Dr. Derek Tidman – a physicist who specialized in electrothermal and electromagnetic acceleration – in the 1990s. Known as the Slingatron, this version of the space catapult is currently being researched by HyperV Technologies.

However, these ideas were never adopted because vast improvements in electromagnetic induction technology were needed to achieve the speed necessary to put heavy payloads into space. But thanks to advancements in high-speed maglev trains, recent attempts to create Hyperloop pods and tracks, and the growth of the commercial aerospace market, the time may be ripe to revisit this concept.

Such is the hope of Jonathan Yaney, an aerospace enthusiast with a long history of co-founding startups. As he describes himself, Yaney is a “serial entrepreneur” who has spent the past 15 years founding companies in the fields of consulting, IT, construction, and aerospace. Now, he has established SpinLaunch for the sake of launching satellites into space.

SpinLaunch’s company logo. Credit: SpinLaunch

And while Yaney has been known for being rather recluse, TechCrunch recently secured an exclusive interview and gained access to the company hangar. According to multiple sources they cite, Yaney and the company he founded are launching a crowdfunding campaign to raise the $30 million in Series A funding to develop the catapult technology. In the course of the interview, Yaney expressed his vision for space exploration as follows:

“Since the dawn of space exploration, rockets have been the only way to access space. Yet in 70 years, the technology has only made small incremental advances. To truly commercialize and industrialize space, we need 10x tech improvement.”

According to a source cited by TechCrunch, SpinLaunch’s design would involve a centrifuge that accelerates payloads to speeds of up to 4,828 km/h (3,000 mph). Additionally, the cargo could be equipped with supplemental rockets to escape Earth’s atmosphere. By replacing rocket boosters with a kinetic launch system, SpinLaunch’s concept would rely on principles similar to those explored by NASA.

But as he went on to explain, the method his company is exploring is different. “SpinLaunch employs a rotational acceleration method, harnessing angular momentum to gradually accelerate the vehicle to hypersonic speeds,” he said. “This approach employs a dramatically lower cost architecture with much lower power.” Utilizing this technology, Yaney estimates that the costs of individual launches could be reduced to $500,000 – essentially, by a factor of 10 to 200.

A lunar base, as imagined by NASA in the 1970s. Credit: NASA

According to Bloomberg Financial, not much more is known about the company or its founder beyond a brief description. However, according to SEC documents cited by TechCrunch, Yaney managed to raise $1 million in equity in 2014 and $2.9 million in 2015. The same documents indicate that he was $2.2 million in debt by mid-2017 and another $2 million in debt by late 2017.

Luckily, the Hawaii state senate introduced a bill last month that proposed issuing $25 million in bonds to assist SpinLaunch with constructing its space catapult. Hawaii also hopes to gain construction contracts for the launch system as part of its commitment to making space accessible. As it states in the bill:

“[T]he department of budget and finance, with the approval of the governor, is authorized to issue special purpose revenue bonds in a total amount not to exceed $25,000,000, in one or more series, for the purpose of assisting SpinLaunch Inc., a Delaware corporation, in financing the costs relating to the planning, design, construction, equipping, acquisition of land, including easements or other interests therein, and other tangible assets for an electrically powered, kinetic launch system to transport small satellites into low Earth orbit.”

In the meantime, Yaney is looking to the public and several big venture capital firms to raise the revenue he needs to make his vision a reality. Of course, beyond the issue of financing, several technical barriers still need to be addressed before a space catapult could be realized. The most obvious of these is how to overcome the air resistance produced by Earth’s dense atmosphere.

However, Yaney was optimistic in his interview with TechCrunch, claiming that his company is investigating these and other challenges:

“During the last three years, the core technology has been developed, prototyped, tested and most of the tech risk retired. The remaining challenges are in the construction and associated areas that all very large hardware development and construction projects face.”

There’s no indication of when such a system might be complete, but that’s to be expected at this point. However, with the support of the Hawaiian government and some additional capital, his company is likely to secure its Series A funding and begin moving to the next phase of development. Much like the Hyperloop, this concept may prove to be one of those ideas that keep advancing because of the people who are willing to make it happen!

And be sure to check out this video about SpinLaunch’s crowdfunding campaign, courtesy of Scott Manley:

Further Reading: TechCrunch

Posted on by Matt Williams

Here’s How SpaceX is Planning to Recover Rocket Fairings: a Boat With a Net Called Mr. Steven

"Mr. Steven", SpaceX's platform for retrieving fairings, is taking to sea. Credit: Pauline Acalin/Teslarati

When visionary entrepreneur Elon Musk founded SpaceX in 2002, he did so with the intention of rekindling human space exploration and sending humans to Mars. Intrinsic to this vision was the reduction of costs associated with individual launches, which has so far been focused on the development of reusable first-stage rockets. However, the company recently announced that they are looking to make their rocket’s payload fairings reusable as well.

The payload fairing is basically the disposable shell at the top of the rocket that protects the cargo during launch. Once the rocket reaches orbit, the fairings falls away to release the payload to space and are lost. But if they could be retrieved, it would reduce launch cost by additional millions. Known as “Mr. Steven”, this new retrieval system consists of a platform ship, extended arms, and a net strung between them.

Mr. Steven is not unlike SpaceX’s Autonomous Spaceport Drone Ships (ASDS), which are used to retrieve first stage rocket boosters at sea. SpaceX has two operational drone ships, including Just Read the Instructions – which is stationed in the Pacific to retrieve launches from Vandenberg – and Of Course I Still Love You, which is stationed in the Atlantic to retrieve launches from Canaveral.

The first ten IridiumNEXT satellites are stacked and encapsulated in the Falcon 9 fairing for launch from Vandenberg Air Force Base, Ca., in early 2017. Credit: Iridium

Recently, Teslarati’s Pauline Acalin captured some photographs of Mr. Steven while it was docked on the California coast near Vandenberg Air Force Base, where it preparing to head out to sea in support of the latest Falcon 9 launch. Known as the PAZ Mission, this launch will place a series of Spanish imaging satellites in orbit, as well as test satellites that will be part of SpaceX’s plan to provide broadband internet service.

Originally scheduled for Wednesday, February 21st, the launch was scrubbed due to strong upper level winds. It is currently scheduled to take place at 6:17 a.m. PST (14:17 UTC) on Thursday, February 22nd, from Space Launch Complex 4 East (SLC-4E) at the Vandenburg Air Force Base. After the cargo is deployed to orbit, the fairings will fall back slowly to Earth thanks to a set of geotagged parachutes.

These chutes will guide the fairings down to the Pacific Ocean, where Mr. Steven will sail to meet them. The fairings, if all goes as planned, will touch down gently into the net and be recovered for later use. In March of 2017, SpaceX successfully recovered a fairing for the first time, which allowed them to recoup an estimated $6 million dollars from that launch.

At present, SpaceX indicates that the cost of an individual Falcon 9 launch is an estimated $62 million. If the payload fairings can be recovered regularly, that means that the company stands to recoup an additional 10% of every individual Falcon 9 launch.

This news comes on the heels of SpaceX having successfully launched their Falcon Heavy rocket, which carried a Tesla Roadster with “Spaceman” into orbit. The launch was made all the more impressive due to the fact that two of the three rocket boosters used were successfully recovered. The core booster unfortunately crashed while attempted to land on one of the ASDS at sea.

At this rate, SpaceX may even start trying to recover their rocket’s second stages in the not-too-distant future. If indeed all components of a rocket are reusable, the only costs associated with individual launches will be the one-time manufacturing cost of the rocket, the cost of fuel, plus any additional maintenance post-launch.

For fans of space exploration and commercial aerospace, this is certainly exciting news! With every cost-cutting measure, the possibilities for scientific research and crewed missions increase exponentially. Imagine a future where it costs roughly the same to deploy space habitats to orbit as it does to deploy commercial satellites, and sending space-based solar arrays to orbit (and maybe even building a space elevator) is financially feasible!

It might sound a bit fantastic, but when the costs are no longer prohibitive, a lot of things become possible.

Further Reading: Teslatari, TechCrunch

Posted on by Matt Williams

Russia and China Are Working on Space and Counterspace Weapons

The first Long March 5 rocket being rolled out for launch at Wenchang in late October 2016. Credit: Su Dong/China Daily

Every year, the Department of National Intelligence (DNI) releases its Worldwide Threat Assessment of the US Intelligence Community. This annual report contains the intelligence community’s assessment of potential threats to US national security and makes recommendations accordingly. In recent years, these threats have included the development and proliferation of weapons, regional wars, economic trends, terrorism, cyberterrorism, etc.

This year’s assessment, which was released on February 8th, 2018, was certainly a mixed bag of warnings. Among the many potential threats to national security, the authors emphasized the many recent developments taking place in space. According to their assessment, the expansion of the global space industry, growing cooperation between the private and public sector, and the growth of various states in space, could constitute a threat to US national security.

Naturally, the two chief actors that are singled out were China and Russia. As they indicate, these countries will be leading the pack in the coming years when it comes to expanding space-based reconnaissance, communications and navigation systems. This will not only enable their abilities (and those of their allies) when it comes to space-based research, but will have military applications as well.

The second flight of the Long March 5 lifting off from Wenchang on July 2nd, 2017. Credit: CNS

As they state in the section of the report titled “Space and Counhttps://www.dni.gov/files/documents/Newsroom/Testimonies/2018-ATA—Unclassified-SSCI.pdfterspace“:

“Continued global space industry expansion will further extend space-enabled capabilities and space situational awareness to nation-state, nonstate, and commercial space actors in the coming years, enabled by the increased availability of technology, private-sector investment, and growing international partnerships for shared production and operation… All actors will increasingly have access to space-derived information services, such as imagery, weather, communications, and positioning, navigation, and timing for intelligence, military, scientific, or business purposes.”

A key aspect of this development is outlined in the section titled “Emerging and Disruptive Technology,” which addresses everything from the development of AI and internet technologies to additive manufacturing and advanced materials. In short, it not just the development of new rockets and spacecraft that are at issue here, but the benefits brought about by cheaper and lighter materials, more rapid information sharing and production.

“Emerging technology and new applications of existing technology will also allow our adversaries to more readily develop weapon systems that can strike farther, faster, and harder and challenge the United States in all warfare domains, including space,” they write.

Artist’s illustration of China’s 8-ton Tiangong-1 space station, which is expected to fall to Earth in late 2017. Credit: CMSE

Specifically, anti-satellite (ASAT) weapons are addressed as the major threat. Such technologies, according to the report, have the potential to reduce US and allied military effectiveness by disrupting global communications, navigation and coordination between nations and armies. These technologies could be destructive, in the form of anti-satellite missiles, but also nondestructive – i.e. electromagnetic pulse (EMP) devices. As they indicate:

“We assess that, if a future conflict were to occur involving Russia or China, either country would justify attacks against US and allied satellites as necessary to offset any perceived US military advantage derived from military, civil, or commercial space systems. Military reforms in both countries in the past few years indicate an increased focus on establishing operational forces designed to integrate attacks against space systems and services with military operations in other domains.”

The authors further anticipate that Russian and Chinese destructive ASAT technology could reach operational capacity within a few years time. To this end, they cite recent changes in the People’s Liberation Army (PLA), which include the formation of military units that have training in counter-space operations and the development of ground-launched ASAT missiles.

While they are not certain about Russia’s capability to wage ASAT warfare, they venture that similar developments are taking place. Another area of focus is the development of directed-energy weapons for the purpose of blinding or damaging space-based optical sensors. This technology is similar to what the US investigated decades ago for the sake of strategic missile defense – aka. the Strategic Defense Initiative (SDI).

An artist’s concept of a Space Laser Satellite Defense System. Credit: USAF

While these weapons would not be used to blow up satellites in the conventional sense, they would be capable of blinding or damaging sensitive space-based optical sensors. On top of that, the report cites how Russia and China continue to conduct on-orbit activities and launching satellites that are deemed “experimental”. A good example of this was a recent proposal made by researchers from the Information and Navigation College at China’s Air Force Engineering University.

The study which detailed their findings called for the deployment of a high-powered pulsed ablative laser that could be used to break up space junk. While the authors admit that such technology can have peaceful applications – ranging from satellite inspection, refueling and repair – they could also be used against other spacecraft. While the United States has been researching the technology for decades, China and Russia’s growing presence in space threatens to tilt this balance of power.

Moreover, there are the loopholes in the existing legal framework – as outlined in the Outer Space Treaty – which the authors believe China and Russia are intent on exploiting:

“Russia and China continue to publicly and diplomatically promote international agreements on the nonweaponization of space and “no first placement” of weapons in space. However, many classes of weapons would not be addressed by such proposals, allowing them to continue their pursuit of space warfare capabilities while publicly maintaining that space must be a peaceful domain.”

Artist’s impression of a laser removing orbital debris, based on NASA pictures. Credit: Fulvio314/NASA/Wikipedia Commons

For example, the Outer Space Treaty bars signatories from placing weapons of mass destruction in orbit of Earth, on the Moon, on any other celestial body, or in outer space in general. By definition, this referred to nuclear devices, but does not extend to conventional weapons in orbit. This leaves room for antisatellite platforms or other conventional space-based weapons that could constitute a major threat.

Beyond China and Russia, the report also indicates that Iran’s growing capabilities in rocketry and missile technology could pose a threat down the road. As with the American and Russian space programs, developments in space rocketry and ICBMs are seen as being complimentary to each other:

“Iran’s ballistic missile programs give it the potential to hold targets at risk across the region, and Tehran already has the largest inventory of ballistic missiles in the Middle East. Tehran’s desire to deter the United States might drive it to field an ICBM. Progress on Iran’s space program, such as the launch of the Simorgh SLV in July 2017, could shorten a pathway to an ICBM because space launch vehicles use similar technologies.”

All told, the report makes some rather predictable assessments. Given China and Russia’s growing power in space, it is only natural that the DNI would see this as a potential threat. However, that does not mean that one should assume an alarmist attitude. When it comes to assessing threats, points are awarded for considering every contingency. But if history has taught us anything, it’s that assessment and realization are two very different things.

Remember Sputnik? The lesson there was clear. Don’t panic!

Further Reading: DNI

Posted on by Matt Williams

The Next Mars Rover’s Wheels Won’t Get Torn Apart by the Red Planet

The Mars Spring Tire being tested at NASA GRS' Slope lab. Credit: NASA/JPL

The Curiosity Rover has made some incredible discoveries during the five years it has been operating on the surface of Mars. And in the course of conducting its research, the rover has also accrued some serious mileage. However, it certainly came as a surprise when during a routine examinations in 2013, members of the Curiosity science team noted that its wheels had suffered rips in their treads (followed by breaks reported in 2017).

Looking to the future, researchers at NASA’s Glenn Research Center hope to equip next-generation rovers with a new wheel. It is based on the “Spring Tire“, which NASA developed with Goodyear back in the mid-2000s. However, rather than using coiled steel wires woven into a mesh pattern (which was part of the original design) a team of NASA scientists has created a more durable and flexible version which could revolution space exploration.

When it comes right down to it, the Moon, Mars, and other bodies in the Solar System have harsh, punishing terrain. In the case of the Moon, the main issue is the regolith (aka. Moon dust) which covers the majority of its surface. This fine dust is essentially jagged bits of lunar rock which play havoc with engines and machine components. On Mars, the situation is slightly different, with regolith and sharp rocks covering most of the terrain.

Image taken by the Mars Hand Lens Imager (MAHLI) camera showing the condition of Curiosity’s left-middle and left-rear wheels. Credit: NASA/JPL-Caltech/MSSS

In 2013, after just a year on the surface, the Curiosity rover’s wheels began to show signs of wear and tear due it traversing unexpectedly harsh terrain. This led many to worry that the rover might not be able to complete its mission. It also led many at NASA’s Glenn Research Center to reconsider a design they had been working on almost a decade prior, which was intended for renewed missions to the Moon.

For NASA Glenn, tire development has been a focus of research for about a decade now. In this respect, they are returning to a time-honored tradition of NASA engineers and scientists, which began back in the Apollo era. At the time, both the American and Russian space programs were evaluating multiple tires designs for use on the lunar surface. Overall, three major designs were proposed.

First, you had the wheels specially designed for Lunokhod rover, a Russian vehicle whose name literally translates to “Moon Walker”. The wheel design for this rover consisted of eight rigid-rim, wire-mesh tires that were connected to their axles by bicycle-type spokes. Metal cleats were also mounted on the outside of the tire to ensure better traction in the lunar dust.

Then there was NASA’s concept for a Modularized Equipment Transporter (MET), which was developed with the support of Goodyear. This unpowered cart came with two nitrogen-filled, smooth rubber tires to make it easier to pull the cart through lunar soil and over rocks. And then there was the design for the Lunar Roving Vehicle (LRV), which was the last NASA vehicle to visit the Moon.

This crewed vehicle, which Apollo astronauts used to drive around on the challenging lunar surface, relied on four large, flexible wire-mesh wheels with stiff inner frames. During the mid-2000s, when NASA began planning on mounting new missions to the Moon (and future missions to Mars), they began reevaluating the LRV tire and incorporating new materials and technologies into the design.

The fruit of this renewed research was the Spring Tire, which was the work of mechanical research engineer Vivake Asnani, who worked closely with Goodyear to develop it. The design called for an airless, compliant tire made up of hundreds of coiled steel wires, which were then woven into a flexible mesh. This not only ensured light weight, but also gave the tires the ability to support high loads while conforming to the terrain.

To see how the Spring Tire would fare on Mars, engineers at NASA’s Glenn Research Center began testing them in the Slope lab, where they ran them through an obstacle course that simulated the Martian environment. While the tires performed generally well in simulated sand, they experienced problems when the wire mesh deformed after passing over jagged rocks.

To address this, Colin Creager and Santo Padua (a NASA engineer and materials scientist, respectively) discussed possible alternatives. In time, they agreed the steel wires should be replaced with nickel titanium, a shape memory alloy that is capable of retaining its shape under tough conditions. As Padua explained in a NASA Glenn video segment, the inspiration to use this alloy was very serendipitous:

“I just happened to be over in the building here, where the Slope lab is. And I was over here for a different meeting for the work that I do in shape memory alloys, and I happen to run into Colin in the hall. And I was like ‘what are you doing back and why aren’t you over in the impact lab?’ – because I knew him as a student. He said, ‘well, I’ve graduated, and I’ve been working out here full-time for awhile… I work in Slope.”

Despite working at JPL for ten years, Padua had not seen the Slope lab before and accepted an invitation to see what they were working on. After entering the lab and looking at the Spring Tires they were testing, Padua asked if they were experiencing problems with deformation. When Creager admitted that they were, Padua proposed a solution which just happened to be his field of expertise.

“I had never even heard of the term shape memory alloys before, but I knew [Padua] was a materials science engineer,” said Creager. “And so, since then we’ve been collaborating on these tires using his materials expertise, especially in shape memory alloys, to come up with this new tire that we think is really going to revolutionize planetary rover tires and potentially even tires for Earth too.”

The key to shape memory alloys is their atomic structure, which is assembled in such a way that the material “remember” its original shape and is able to return to it after being subjected to deformation and strain. After building the shape memory alloy tire, the Glenn engineers sent it to the Jet Propulsion Laboratory, where it was tested in the Mars Life Test Facility.

Overall, the tires not only performed well in simulated Martian sand, but were able to withstand going over punishing rocky outcroppings without difficulty. Even after the tires were deformed all the way down to their axles, they were able to retain their original shape. They also managed to do this while carrying a significant payload, which is another prerequisite when developing tires for exploration vehicles and rovers.

The priorities for the Mars Spring Tire (MST) are to offer greater durability, better traction in soft sand, and lighter weight. As NASA indicates on the MST website (part of the Glenn Research Center’s website), there are three major benefits to developing high performing compliant tires like the Spring Wheel:

“First, they would allow rovers to explore greater regions of the surface than currently possible. Secondly, because they conform to the terrain and do not sink as much as rigid wheels, they can carry heavier payloads for the same given mass and volume. Lastly, because the compliant tires can absorb energy from impacts at moderate to high speeds, they can be used on crewed exploration vehicles which are expected to move at speeds significantly higher than the current Mars rovers.”

The first available opportunity to test these tires out is just a few years away, when NASA’s Mars 2020 Rover will be sent to the surface of the Red Planet. Once there, the rover will pick up where Curiosity and other rovers have left off, searching for signs of life in Mars’ harsh environment. The rover is also tasked with preparing samples that will eventually be returned to Earth by a crewed mission, which is expected to take place sometime in the 2030s.

Further Reading: NASA, CNET

Posted on by Matt Williams

The X3 Ion Engine Test Break Thrust Records

A prototype Hall-effect thruster being tested at NASA's Glenn Research Center. Credit: NASA

When it comes to the future of space exploration, a number of new technologies are being investigated. Foremost among these are new forms of propulsion that will be able to balance fuel-efficiency with power. Not only would engines that are capable of achieving a great deal of thrust using less fuel be cost-effective, they will be able to ferry astronauts to destinations like Mars and beyond in less time.

This is where engines like the X3 Hall-effect thruster comes into play. This thruster, which is being developed by NASA’s Glenn Research Center in conjunction with the US Air Force and the University of Michigan, is a scaled-up model of the kinds of thrusters used by the Dawn spacecraft. During a recent test, this thruster shattered the previous record for a Hall-effect thruster, achieving higher power and superior thrust.

Hall-effect thrusters have garnered favor with mission planners in recent years because of their extreme efficiency. They function by turning small amounts of propellant (usually inert gases like xenon) into charged plasma with electrical fields, which is then accelerated very quickly using a magnetic field. Compared to chemical rockets, they can achieve top speeds using a tiny fraction of their fuel.

Artist’s concept of Dawn mission using its blue ion engine to reach Ceres in the distance. Credit: NASA/JPL

However, a major challenge so far has been building a Hall-effect thruster that is capable of achieving high levels of thrust as well. While fuel efficient, conventional ion engines typically produce only a fraction of the thrust produced by rockets that rely on solid-chemical propellants. Hence why NASA has been developing the scaled-up model X3 thruster in conjunction with its partners.

The development of the thruster has been overseen by Alec Gallimore, a professor of aerospace engineering and the Robert J. Vlasic Dean of Engineering at the University of Michigan. As he indicated in a recent Michigan News press statement:

“Mars missions are just on the horizon, and we already know that Hall thrusters work well in space. They can be optimized either for carrying equipment with minimal energy and propellant over the course of a year or so, or for speed—carrying the crew to Mars much more quickly.”

In recent tests, the X3 shattered the previous thrust record set by a Hall thruster, achieving 5.4 newtons of force compared with the old record of 3.3 newtons. The X3 also more than doubled the operating current (250 amperes vs. 112 amperes) and ran at a slightly higher power than the previous record-holder (102 kilowatts vs. 98 kilowatts). This was encouraging news, since it means that the engine can offer faster acceleration, which means shorter travel times.

Scott Hall makes some final adjustments on the thruster before the test begins. Credit: NASA

The test was carried about by Scott Hall and Hani Kamhawi at the NASA Glenn Research Center in Cleveland. Whereas Hall is a doctoral student in aerospace engineering at U-M, Kamhawi is NASA Glenn research scientist who has been heavily involved in the development of the X3. In addition, Kamhawi is also Hall’s NASA mentor, as part of the NASA Space Technology Research Fellowship (NSTRF).

This test was the culmination of more than five years of research which sought to improve upon current Hall-effect designs. To conduct the test, the team relied on NASA Glenn’s vacuum chamber, which is currently the only chamber in the US that can handle the X3 thruster. This is due to the sheer amount of exhaust the thruster produces, which can result in ionized xenon drifting back into the plasma plume, thus skewing the test results.

NASA Glenn’s setup is the only one with a vacuum pump powerful enough to create the conditions necessary to keep the exhaust clean. Hall and Kamhawi also had to build a custom thrust stand to support the X3’s 227 kg (500 pound) frame and withstand the force it generates, since existing stands were not up to the task. After securing a test window, the team spent four weeks prepping the stand, the thruster, and setting up all the necessary connections.

All the while, NASA researchers, engineers and technicians were on hand to provide support. After 20 hours of pumping to achieve a space-like vacuum inside the chamber, Hall and Kamhawi conducted a series of tests where the engine would be fired for 12-hours straight. Over the course of 25 days, the team brought the X3 up to its record-breaking power, current and thrust levels.

A side shot of the X3 firing at 50 kilowatts. Credit: NASA

Looking ahead, the team plans to conduct more tests in Gallimore’s lab at U-M using an upgraded vacuum chamber. These upgrades will are schedules to be completed by January of 2018, and will enable the team to conduct future tests in-house. This upgrade was made possible thanks to a $1 million USD grant, contributed in part by the Air Force Office of Scientific Research, with additional support provided by the Jet Propulsion Laboratory and U-M.

The X3’s power supplies are also being developed by Aerojet Rocketdyne, the Sacramento-based rocket and missile propulsion manufacturer that is also the lead on the propulsion system grant from NASA. By Spring of 2018, the engine is expected to be integrated with these power systems; at which point, a series of 100-hour tests that will once again be conducted at the Glenn Research Center.

The X3 is one of three prototypes that NASA is investigating for future crewed missions to Mars, all of which are intended to reduce travel times and reduce the amount of fuel needed. Beyond making such missions more cost-effective, the reduced transit times are also intended to reduce the amount of radiation astronauts will be exposed to as they travel between Earth and Mars.

The project is funded through NASA’s Next Space Technologies for Exploration Partnership (Next-STEP), which supports not just propulsion systems but also habitat systems and in-space manufacturing.

Further Reading: Michigan News

Posted on by Matt Williams

Second Hyperloop Pod Design Competition A Success

At the recent ceremony for the Hyperloop Pod Competition, Musk announced that his concept for a high-speed train might work better on Mars. Credit: HTT

Back in 2012, Elon Musk proposed a revolutionary idea that he described as the “fifth form of transportation“. Known as the Hyperloop, his proposal called for the creation of a high-speed mass transit system where aluminum pod cars traveled through a low-pressure steel tube. This system, he claimed, would be able to whisk passengers from San Francisco to Los Angeles in just 35 minutes.

At the time, Musk claimed he was too busy to build such a system, but that others were free to take a crack at it. Nevertheless, the SpaceX founder has remained involved in the Hyperloop’s development by hosting the Hyperloop Pod Design Competition, an incentive competition involving student and engineering teams. The second of these competitions was recently held and featured some impressive pods achieving impressive speeds.

The Pod Design Competition was first announced in June of 2015, and was quickly joined by over 700 teams. By January of 2017, 100 teams were selected to take part in the first competition, which was held from January 27th to 29th at the SpaceX’s Hyperloop Test Track (located in Hawthorne, California). Also known as the Hypertube, this track consists of a partial-vacuum steel tube that measures 1.6 km (1 mi) long and 1.83 meters in diameter.

Team MIT’s Hyperloop pod car design. Credit: MIT/Twitter

The winning design, which was provided by a team from MIT, consisted of a car that would rely on electrodynamic suspension to achieve a cruising speed of 110 m/s (396 km/h; 246 mph). Based on the positive response and submissions from the first competition, SpaceX decided to hold the Hyperloop Pod Competition II, which took place this past weekend (August 25th to 27th, 2017) at their Hypertube test track.

Whereas the first competition involved a series of tests designed to accelerate the development of prototypes, the second had only one criterion: maximum speed. The competition was open to both new and returning teams, the latter of which had already tested their pods in the first competition. Twenty-five teams registered in the competition, representing universities and technical institutions from all over the world.

But in the end, only three teams made the cut and competed on Sunday, August 27th, having met the pre-run criteria. The winning entry came from WARR Hyperloop, a team made up of student from the Technical University of Munich. During the test run, their pod achieved a top speed of 324 km/h ( 201 mph), which was far in excess of the second place team.

It was even more impressive than WARR’s previous test run during the first competition – where their pod achieved a maximum speed of about 93 km (58 mph). The WARR pod was also the only one that attempted to reach its maximum speed during the competition. Their success was due in part to the pod’s design, which is fabricated from carbon fiber to ensure that it is lightweight and durable.

https://www.instagram.com/p/BYU1EttgwJE/?taken-by=elonmusk

Musk praised the teams effort during the competition and took to Twitter to post the results of the latest pod tests. As he tweeted at 17:32, shortly after the test run, “Congratulations to WARR team from Tech Univ Munich for winning 2nd competition! Peak speed of 324 km/h, which is over 200 mph!!”

Some additional comments followed later that day and on the following morning (Monday, August 28th):

“Might be possible to go supersonic in our test Hyperloop tube, even though it’s only 0.8 miles long. Very high accel/decel needed… To be clear, a Hyperloop passenger version wouldn’t have intense light strobe effect (just for testing), nor uncomfortable acceleration.”

“Btw, high accel only needed because tube is short. For passenger transport, this can be spread over 20+ miles, so no spilt drinks.”

“Will run the SpaceX pusher sled later this week and see what it can do.”

Musk posted the video of the WARR pod’s performance on Twitter and to his Instagram account (see below). He  also announced that SpaceX and his latest startup – The Boring Company – will be hosting a third pod design competition next year. The stakes, he claimed, would be even higher for this competition, with pods expected to reach speeds of over 500 km/h (310 mi) on the test track.

While this is still far from the speeds that Musk originally envisioned in his white paper – up to 1280 km/h (800 mph) – it does represent a significant progression. And with six startups now looking to make the Hyperloop a reality – including Hyperloop Transportation Technologies (HTT) and Hyperloop One – the only question is, how long before the “fifth mode of transportation” becomes a reality?

Be sure to check out this video of the test track during the first Pod Design Competition, courtesy of SpaceX:

Further Reading: TechCrunch, SpaceX, Instagram

Posted on by Matt Williams

NASA Reignites Program for Nuclear Thermal Rockets

Artist's concept of a bimodal nuclear rocket making the journey to the Moon, Mars, and other destinations in the Solar System. Credit: NASA

In its pursuit of missions that will take us back to the Moon, to Mars, and beyond, NASA has been exploring a number of next-generation propulsion concepts. Whereas existing concepts have their advantages – chemical rockets have high energy density and ion engines are very fuel-efficient – our hopes for the future hinge on us finding alternatives that combine efficiency and power.

To this end, researchers at NASA’s Marshall Space Flight Center are once again looking to develop nuclear rockets. As part of NASA’s Game Changing Development Program, the Nuclear Thermal Propulsion (NTP) project would see the creation of high-efficiency spacecraft that would be capable of using less fuel to deliver heavy payloads to distant planets, and in a relatively short amount of time.

As Sonny Mitchell, the project of the NTP project at NASA’s Marshall Space Flight Center, said in a recent NASA press statement:

“As we push out into the solar system, nuclear propulsion may offer the only truly viable technology option to extend human reach to the surface of Mars and to worlds beyond. We’re excited to be working on technologies that could open up deep space for human exploration.”

Nuclear reactors (like the one pictured here) are being considered by NASA’s Marshall Space Flight Center for possible future missions. Credit: NASA

To see this through, NASA has entered into a partnership with BWX Technologies (BWXT), a Virginia-based energy and technology company that is a leading supplier of nuclear components and fuel to the U.S. government. To assist NASA in developing the necessary reactors that would support possible future crewed missions to Mars, the company’s subsidiary (BWXT Nuclear Energy, Inc.) was awarded a three-year contract worth $18.8 million.

During this three years in which they will be working with NASA, BWXT will provide the technical and programmatic data needed to implement NTP technology. This will consist of them manufacturing and testing prototype fuel elements and helping NASA to resolve any nuclear licensing and regulatory requirements. BWXT will also aid NASA planners in addressing the issues of feasibility and affordably with their NTP program.

As Rex D. Geveden, BWXT’s President and Chief Executive Officer, said of the agreement:

“BWXT is extremely pleased to be working with NASA on this exciting nuclear space program in support of the Mars mission. We are uniquely qualified to design, develop and manufacture the reactor and fuel for a nuclear-powered spacecraft. This is an opportune time to pivot our capabilities into the space market where we see long-term growth opportunities in nuclear propulsion and nuclear surface power.”

In an NTP rocket, uranium or deuterium reactions are used to heat liquid hydrogen inside a reactor, turning it into ionized hydrogen gas (plasma), which is then channeled through a rocket nozzle to generate thrust. A second possible method, known as Nuclear Electric Propulsion (NEC), involves the same basic reactor converted its heat and energy into electrical energy which then powers an electrical engine.

Artist’s concept of a Bimodal Nuclear Thermal Rocket in Low Earth Orbit. Credit: NASA

In both cases, the rocket relies on nuclear fission to generates propulsion rather than chemical propellants, which has been the mainstay of NASA and all other space agencies to date. Compared to this traditional form of propulsion, both types of nuclear engines offers a number of advantages. The first and most obvious is the virtually unlimited energy density it offers compared to rocket fuel.

This would cut the total amount of propellant needed, thus cutting launch weight and the cost of individual missions. A more powerful nuclear engine would mean reduced trip times. Already, NASA has estimated that an NTP system could make the voyage to Mars to four months instead of six, which would reduce the amount of radiation the astronauts would be exposed to in the course of their journey.

To be fair, the concept of using nuclear rockets to explore the Universe is not new. In fact, NASA has explored the possibility of nuclear propulsion extensively under the Space Nuclear Propulsion Office. In fact, between 1959 and 1972, the SNPO conducted 23 reactor tests at the Nuclear Rocket Development Station at AEC’s Nevada Test Site, in Jackass Flats, Nevada.

In 1963, the SNPO also created the Nuclear Engine for Rocket Vehicle Applications (NERVA) program to develop nuclear-thermal propulsion for long-range crewed mission to the Moon and interplanetary space. This led to the creation of the NRX/XE, a nuclear-thermal engine which the SNPO certified as having met the requirements for a crewed mission to Mars.

Artist’s concept of a bimodal nuclear rocket slowing down to establish orbit around Mars. Credit: NASA

The Soviet Union conducted similar studies during the 1960s, hoping to use them on the upper stages of  of their N-1 rocket. Despite these efforts, no nuclear rockets ever entered service, owing to a combination of budget cuts, loss of public interest, and a general winding down of the Space Race after the Apollo program was complete.

But given the current interest in space exploration, and ambitious mission proposed to Mars and beyond, it seems that nuclear rockets may finally see service. One popular idea that is being considered is a multistage rocket that would rely on both a nuclear engine and conventional thrusters – a concept known as a “bimodal spacecraft”. A major proponent of this idea is Dr. Michael G. Houts of the NASA Marshall Space Flight Center.

In 2014, Dr. Houts  conducted a presentation outlining how bimodal rockets (and other nuclear concepts) represented “game-changing technologies for space exploration”. As an example, he explained how the Space Launch System (SLS) – a key technology in NASA’s proposed crewed mission to Mars – could be equipped with chemical rocket in the lower stage and a nuclear-thermal engine on the upper stage.

In this setup, the nuclear engine would remain “cold” until the rocket had achieved orbit, at which point the upper stage would be deployed and the reactor would be activated to generate thrust. Other examples cited in the report include long-range satellites that could explore the Outer Solar System and Kuiper Belt and fast, efficient transportation for manned missions throughout the Solar System.

The company’s new contract is expected to run through Sept. 30th, 2019. At that time, the Nuclear Thermal Propulsion project will determine the feasibility of using low-enriched uranium fuel. After that, the project then will spend a year testing and refining its ability to manufacture the necessary fuel elements. If all goes well, we can expect that NASA’s “Journey to Mars” might just incorporate some nuclear engines!

Further Reading: NASA, BWXT News