August, 2014Archive for

Deflecting Disaster – Can we Prevent Armageddon via Asteroid?

Sunday, August 31st, 2014

The threat of a large asteroid collision with the earth is not just the basis of a good movie plot, but an actual concern that scientists are monitoring daily.

Scientists use the Torino Scale to determine the level of concern for discovered Near Earth Asteroids (NEOs). As discussed in a previous article, the Torino scale ranks NEOs on a zero to ten scale based on both the probability of impact, as well as the potential devastation due to size. An asteroid greater than about one mile in diameter would impact the earth with more than one million times the energy of the nuclear bomb dropped on Hiroshima. This would not only wipe out anything within a 200 mile radius of the impact point, but due to dust and debris thrown into the atmosphere, would cause worldwide devastation.

Avoidance Techniques

There are essentially two frames of thought when considering asteroid deflection – direct and indirect intervention. Direct intervention send some sort of explosive device directly at the asteroid to obliterate it into fragments small enough to burn up in Earth’s atmosphere. Indirect intervention exploits the fact that with adequate warning, an asteroid’s trajectory need only be modified by a fraction of a degree over time to miss an Earth impact. Thus, slow and consistent techniques of trajectory modification are employed.

asteroidDirect Intervention

This is pretty straight forward. We would send a rocket directly at the asteroid to impact its surface, modifying the trajectory or reducing it to acceptably small fragments. This could either be a high-mass spacecraft, or a nuclear weapon detonating upon collision. This is currently the best option for asteroid deflection, as it requires the least amount of lead time, and is the simplest (and therefore cheapest) spacecraft necessary.

In 2005 the Deep Impact spacecraft successfully collided with the nucleus of comet Tempel 1. This was the first time a spacecraft has impacted a comet or asteroid. The comet’s trajectory was modified by about four inches. Knowledge gained from this impact is vital for understanding the effects of spacecraft collisions with celestial bodies.

Indirect Intervention

Example Gravity Tractor spacecraft

As opposed to a quick solution such as a nuclear strike, the indirect redirection of an asteroid has the likelihood of a higher success rate due to its slow trajectory modification approach. In the gravity tractor technique, a relatively large spacecraft would hover next to an asteroid, using its mass to gravitationally pull the asteroid towards it. With adequate lead time, a trajectory modification of a fraction of a degree is all that is necessary to deter an impact event. This also is an effective strategy if the asteroid is actually made up of a collection of asteroids, known as a “rubble pile”, which direct intervention is ineffective against.

In the Event of an Impact Detection

Tomorrow if astronomers discovered an asteroid on a collision course with Earth, would we have the capability of deflecting it? The answer depends on both the size of the asteroid and the time until impact.

Currently there is no known spacecraft equipped to handle an immediate launch to an asteroid. Thus, in the event of impact detection, developing this rocket or retrofitting an existing rocket with asteroid deflection technology would take significant time.

Dr. Edward Lu, physicist, former astronaut, and head of the private NEO detecting program B612 Foundation, made the following comments when asked in a senate hearing about the duration of time needed to develop and execute an impact asteroid: “I think with 10 years you can do this in a controlled manner with backups and so on. Certainly, with 20 years you could do that. It gets much more difficult the closer in it is, and that is, again, the importance of getting early warning, because the closer it is to you, the more you need to deflect it by to get it to miss… Five years or less, it is really hard unless you have thought the problem through and design things, maybe have components built, maybe have a full system”

If something like a city killing asteroid is discovered to impact the Earth in the next five years, the most likely course of action would be a repeated bombardment of direct impacts. While a single spacecraft may not transfer enough energy to push the asteroid off course, a dozen or more may have the necessary combined effect to avert disaster.

Are Plasma Rockets the Future of Space Travel?

Monday, August 25th, 2014

VASIMR stands for Variable Specific Impulse Magnetoplasma Rocket. It is a rocket technology currently in development by Ad Astra in conjunction with NASA that has the potential to take spacecraft – and ultimately humans – to deep space significantly faster and more efficiently than today’s technology.

Chemical Rockets

The four states of matter based on the atomic bonds

Today’s spacecraft primarily use chemical rockets as their propulsion system. This is used both to launch the vehicle into orbit, as well as propel it to deep space. Sometimes gravitational acceleration is used around the moon or nearby planets to “slingshot” the vehicle, but the primary acquisition of velocity comes from chemical rockets.

These rockets usually consist of multiple chemicals that mix together and combust, forming an expansion of gas that accelerates out the back of the rocket, providing thrust. The biggest disadvantage to chemical rockets is how heavy the fuel is compared to the energy provided. In order to provide adequate thrust to propel a spacecraft to high speeds, a rocket must carry a significant amount of fuel. But in order to get that fuel to space, it must burn more fuel to launch the additional weight. This make today’s chemical rockets quite inefficient.

Plasma

Before discussing how the VASIMR rocket works, we must understand what exactly plasma is. Plasma is the fourth state of matter along with solid, liquid, and gas. Plasma is generated when a gas is ionized: changing the number of electrons in the fundamental structure of the gas. Because of this ionization, plasma is extremely susceptible to electromagnetic fields. This is fundamentally different than the other three states of matter. Plasma is produced by natural high energy phenomenon in the sun and lightning strikes, but can also be artificially produced.

Five steps for thrust in VASIMR

Plasma propulsion

Plasma propulsion is founded in the fact that plasma responds to electromagnetic fields. Because of this, its direction and velocity can be manipulated by strong electromagnets. In VASIMR, a gas such as argon is ionized with radio waves. This argon plasma is then propelled down a tube of electromagnets to create thrust. The electromagnets excite the plasma particles, and can heat the plasma up to more than 1,000,000 degrees Kelvin. This superheated is then forced out the end of the rocket engine, providing the thrust to the spacecraft.

Benefits

The largest benefit of the VASIMR rocket is the reduction in propellant mass. Although it does not possess the high thrust capabilities of a chemical rocket, it is much more suitable for long-duration spaceflight to achieve much faster speeds than current technology. Thus, current plans are to launch spacecraft with traditional chemical rockets, then once in Low Earth Orbit, enable the plasma rockets to propel the craft to its destination. With this process, journeys from Earth to Mars would reduce from seven months with current technology to as little as 40 days.

The Future of Human Spaceflight – Part 2: Mars

Sunday, August 24th, 2014

NASA’s SLS rocket carrying the Orion spacecraft

In the previous article we discussed the transitioning burden of human spaceflight to low Earth orbit (LEO) from NASA’s dependency on the Russians to private industry such as SpaceX and Boeing. In doing so, NASA set its sights on manned deep space missions, that will take place over the next few decades.

In the 1960s NASA pioneered human spaceflight with a series of manned spaceflight programs known as Mercury, Gemini and Apollo. Each program was divided into a series of missions building upon each other as stepping stones to reach the ultimate goal of putting humans on the moon. Apollo 11 was the first to achieve this goal, occurring in July 1969. On December 14, 1972 Apollo 17 left the moon, marking the last time humans traveled beyond LEO.

The Path to Mars

In the same way as the manned spaceflight programs from the 1960s and 1970s, NASA has ostensibly laid out a series of potential mission objectives that ultimately culminate in landing humans on Mars in the 2030s. Though these missions are far from guaranteed (and subject to budget cuts), the Space Launch System (SLS) and Orion spacecraft are taking these milestone missions into account during their design phases.

Canadian Astronaut Chris Hadfield monitoring a plant experiment on the International Space Station

The International Space Station

The first step in our journey to Mars is underway right now. Astronauts on the ISS are performing experiments to better our understanding of long term space exposure to the human body. In a document issued by NASA on May 29th, 2014 entitled “Pioneering Space: NASA’s Next Steps on the Path to Mars”, NASA indicated their research specifically targets “decreased gravity affecting bone, muscle, cardiovascular and sensorimotor systems, nutrition, behavior/performance, immunology and the ability to provide remote medical care via telemedic” It also provides us with a test bed for developing better technologies in areas such as spacecraft docking, life support, and extravehicular activity.

The Moon

While NASA may not be landing humans on the Moon anymore, it still provides an excellent place to test long duration, self sustaining systems in a low-risk environment. The first manned missions of the Orion and SLS, slated for 2021-2022, will send humans into an extended lunar orbit to prove the capabilities and habitability of the spacecraft.

Lunar orbit also is valuable for future missions in that the Moon’s gravity is one-sixth of Earth’s. Conceivably, a long duration mission to Mars could be staged and launched from lunar orbit, reducing the fuel requirements to reach cruising velocity to Mars. In this scenario, a manned rocket could be refueled in lunar orbit, increasing the potential payload launched from Earth and decreasing the cost of the mission.

Asteroid Redirect Mission (ARM)

Artist rendition of a potential asteroid redirect mission spacecraft

In addition to human spaceflight, NASA also has projects involving deep space missions to near Earth asteroids (NEAs). To leverage this technology, NASA has decided to attempt a NEA capture and transfer into lunar orbit using robotic spacecraft powered by a solar electric propulsion (SEP) rocket in 2019. Once placed in lunar orbit, astronauts will take Orion to the asteroid, and attempt Extra Vehicular Activity (EVA). This will be the first time a human has set foot on an asteroid, slated for 2025.

The purpose of this mission is complex. From a scientific standpoint, asteroids are extremely old remnants of the early solar system, thus scientists want a closer look at their chemical makeup to help us understand how the solar system was formed. In terms of technology, it will be an impressive feat to both capture and relocate an asteroid, and SEP technology can later be used to transfer cargo to Mars in anticipation of a manned mission, effectively creating a Martian space station before humans ever arrive. Additionally, it will provide an excellent test of Orion’s ability to rendezvous with robotic spacecraft, and give astronauts a chance to test EVA in a low-gravity environment.

Phobos and Deimos

Before landing humans on Mars, NASA may launch a mission to one of Mars’s moons, Phobos or Deimos. Though scientists currently believe they are captured asteroids rather than pieces of Mars broken off, they could provide access to Martian material accrued from millions of years of meteor strikes to the martian surface. The also provide a test environment for landing men in a deep space environment, as Phobos’s gravity is 650 times weaker than Mars’s.

Artist rendition of the first humans on Mars

Mars Landing

Sometime in the 2030s, NASA plans to attempt the first landing of humans on another planet. This will be a culmination of the aforementioned programs, as well as countless hours of development and testing by NASA, partner space programs, and commercial space companies. As of now a mission to Mars will take a minimum 550 days, with more than 95 percent of that time spent in deep space between Earth and Mars. A Martian lander has yet to be developed, but will come to fruition as scientists and engineers learn more about Mars, and human sustainability in deep space.

The Future of Human Spaceflight – Part 1

Friday, August 15th, 2014

The final Space Shuttle flight launched July 8th, 2011. Since then, the United States has been incapable of putting humans into space with their own spacecraft. It has relied on the Soyuz spacecraft of the Russians to send astronauts into space, at a cost now over $70 million per seat. This is not only inefficient, but puts our entire space program in jeopardy as political tensions with Russia mount.

Orion deep space capsule

The US has not sat idly by, however, following the conclusion of the Space Shuttle program. It has instead turned both to its R&D department as well as commercial spacecraft companies for competing solutions. Ideally, the United States will be capable of putting humans back into space by 2018.

ORION

In a previous article we discussed NASA’s Orion project, a spacecraft designed and built in conjunction with Lockheed Martin. Orion’s purpose is for human deep space missions – the moon, asteroids, Mars, etc. It is not designed for Low Earth Orbit (LEO) Where the International Space Station (ISS) exists. Orion will be launched by the new Space Launch System (SLS), which is the largest rocket ever built, standing at more than 380ft tall. Orion may be used in a manned mission as early as 2021, to send astronauts to an asteroid.

In an upcoming article we’ll discuss the future plans for deep space travel that include plans to go back to the moon, capture an asteroid into lunar orbit, and ultimately putting humans on Mars.

Dragon V2 capsule

CCiCap and CCtCap

Although Orion will satisfy the need for sending humans into deep space, there is still a significant need for LEO spacecraft. Instead of developing it themselves, NASA has created a series of funding initiatives for private companies to design and develop LEO spacecraft for human travel.

The Commercial Crew Integrated Capability (CCiCap) program is an active initiative to fund three chosen companies in their quest for a safe, reliable, and efficient spacecraft to send humans to LEO. On August 3rd, 2012, the Sierra Nevada Corporation, Space Exploration Technologies (SpaceX), and Boeing were chosen to receive a split of the $1.1 billion allocated for the program.

These three companies are now developing their respective spacecraft solutions, hitting predefined milestones of development and testing along the way. They are competing for the first commercial human spaceflight contract in the history of the United States, called the Commercial Crew Transport Capability (CCtCap). This contract could come as early as August 2014. It is unknown if only one of the three competing companies will receive the entire contract, or a joint funding between two programs will occur.

SpaceX Dragon V2

Interior of Dragon V2

SpaceX has been around since 2002, though their first successful launch wasn’t until 2008. Since then, they’ve had remarkable successes in putting satellites into orbit, and were the first private company to send a spacecraft to the ISS.

The Dragon V2 is a modified version of the Dragon cargo spacecraft, fitted with seating for up to seven astronauts. While similar in design to most capsule-based spacecraft, it is equipped with unique features such as soft earth landings (rather than parachuting into the ocean), and complete reusability. Additionally, it has a much more modern and futuristic interface than past human spacecraft.

Reusability is an important goal at SpaceX, as every piece of a rocket that can be reused reduces the cost of spaceflight dramatically. SpaceX is also developing a first stage booster rocket that can safely return to the launch pad it initially launched from. The ultimate goal is to design a craft that is 100% reusable, so only the cost of fuel is required for travel, much like the airline industry is today.

Boeing CST-100 Capsule

Boeing CST-100

The CST-100 is a similar design to the Dragon V2. Boeing has a track record of making fantastic spacecraft in the past, which is it’s biggest benefit. The CST-100, while capable of using multiple launch vehicles (even SpaceX’s Falcon 9), is currently slated to use the Atlas 5 rocket. This rocket has a long history of being very safe and reliable. There is a problem however – Atlas 5 rocket engines come from Russia. With the increasing political tension with Russia, there’s no guarantee we Boeing will have the opportunity to acquire rocket engines for the Atlas 5.

DreamChaser Spaceplane

Sierra Nevada DreamChaser

The DreamChaser is entirely different in it’s design from the Dragon and CST-100. It is much more similar to the space shuttle in that it has wings, and makes runway landings. Like the shuttle, it can be reused once refueled. In addition, the DreamChaser uses a hybrid engines with ethanol based fuel, which is much less volatile than the propellants on the CST-100 and Dragon.
The Dreamchaser has a similar issue with the Boeing craft, in that it also relies on the Atlas 5 rocket to get it to orbit. Additionally, the abort system is more complex than the capsule solutions, as it cannot splashdown in the ocean with parachutes, but is required to glide to a runway.