Deflection – Laser Ablation

Deflection – Laser Ablation

Many issues and engineering solutions need to be addressed in order to land on a NEO and place nuclear devices or other trajectory altering systems there. Although the cost of any NEO protection system will likely be significant, any system requiring a deep-space rendezvous would also require sufficient warning of an impact to be implemented. Additionally, a failure of such a defense system may not allow for a second mitigation effort to be attempted before the object impacts the Earth. A better system would be one that is "on station" and could be used routinely to shape asteroid orbits over long periods of time so that they do not pose a potential threat. The system should also be able to handle the wide range of materials and sizes that constitute the NEO population (current or yet to be discovered). Phased Array Laser Systems (PALS) could be developed and placed in space, either orbiting or lunar based. Space-based laser constellations (SBL) are presently under development and will be flown during the next decade. The feasibility for a PALS based system is discussed below. Laboratory experiments using a 20 kW pulsed laser have shown that the impulse imparted to aluminum targets due to the ejected plasma cloud gives an average surface pressure p = 6,5 x 10' N/amz, or equivalently, an acceleration a = 1.25 x l0"˜ m/sz. Thus, with present technology, an array of laser beam directors can be aimed at an asteroid, meteoroid, or a comet, providing sufficient power to ablate its surface. It is simply a matter of putting in place a sufficient number of lasers to accomplish the mission.

If the collision scenario depicted in Figure l was encountered The PALS firing with a good aspect 'dom L, and sufficient lead time (as shown in the figure,) would have 2-3 months to move the asteroid away from a collision path with the Earth. Only with a sufficiently capable detection system would there be adequate time in advance for the PALS to deflect the asteroid away from the Earth. This fact stresses the need for coupling with PALS an early warning system using optical and/or radar imaging techniques. The AV of 5 km/s is an example of an impulse that yields a "miss distance." In this case, the simulation yields that the asteroid passes in front of the Earth by L25 Earth diameters. An approach requiring significantly less power for PALS would be a gradual shift in the orbit by a long duration, low intensity impulse. This lower energy impulse would reshape the orbit over a long time period, perhaps several orbits. Ideally, for the asteroidal orbit shown in Figures l, 2 and 3, it might conceivable to move the asteroid into an orbit that removes any potential threat to the Earth. From a non-defensive standpoint, it is interesting to contemplate asteroid orbit modification for the purpose of scientific exploration and/or commercial exploitation (i.e., asteroid mining). This application of a PALS may be particularly feasible for small asteroids (less than 100 rn) in orbits that are "easily" modified to a desired rendezvous location for processing.

Deflection – B612 Spaceship

B612 spaceships are more controlled than any other type of deflection.

Lu 04 (Edward Lu is the head of the B612 Foundation, “Why Move an Asteroid?” Testimony before the Subcommittee on Science, Technology and Space of the Senate Commerce Committee, April 7 2004, http://www.astrobio.net/index.php?option=com_retrospection&task=detail&id=972 TDA)

Why does the asteroid need to be moved in a "controlled manner"? If the asteroid is not deflected in a controlled manner, we risk simply making the problem worse. Nuclear explosives for example risk breaking up the asteroid into pieces, thus turning a speeding bullet into a shotgun blast of smaller but still possibly deadly fragments. Explosions also have the drawback that we cannot accurately predict the resultant velocity of the asteroid -- not a good situation when trying to avert a catastrophe. Conversely, moving an asteroid in a controlled fashion also opens up the possibility of using the same technology to manipulate other asteroids for the purposes of resource utilization. How can this be accomplished? This mission is well beyond the capability of conventional chemically powered spacecraft. We are proposing a nuclear powered spacecraft using high efficiency propulsion (ion or plasma engines). Such propulsion packages are currently already under development at NASA as part of the Prometheus Project. In fact, the power and thrust requirements are very similar to the Jupiter Icy Moons Orbiter spacecraft, currently planned for launch around 2012. The B612 spacecraft would fly to, rendezvous with, and attach to a suitably chosen target asteroid (there are many candidate asteroids which are known to be nowhere near a collision course with Earth). By continuously thrusting, the spacecraft would slowly alter the velocity of the asteroid by a fraction of a cm/sec --enough to be clearly measurable from Earth. What will we learn from this? It is important to remember that this mission is merely a first attempt to learn more about the mechanics of asteroid deflection. There are a number of technical complications, as well as many unknowns about the structure and composition of asteroids. However, the way to make progress is to build, fly, and test. Much of what we will learn is generic to many proposed asteroid deflection schemes, with the added benefit of being able to answer important scientific questions about asteroids themselves. The best way to learn about asteroids is to go there. How does this fit into the new Exploration Initiative at NASA? In the near term, this mission would be an ideal way to flight test the nuclear propulsion systems under development as part of the Prometheus Project. It could also serve as a precursor to a crewed mission to visit an asteroid. Such missions have been proposed as intermediate steps to test spacecraft systems for eventual longer term crewed missions to Mars.

Directory: 2011
2011 -> Enterprise Network Management iPost: Implementing Continuous Risk Monitoring at the Department of State
2011 -> Voices of the Old Sea Norman Lewis
2011 -> Malevil Robert Merle
2011 -> The Elephant Keeper’s Children Peter Hoeg
2011 -> January 1: Ecstasy zZz January 2: King of Anything Sara Bareillis
2011 -> Tracks, Mixes, Masters, and More!: Analyzing Preservation Priorities for Multitrack Recordings
2011 -> Department of Electrical Engineering 2011 Annual Report
2011 -> Jv packet •Mars Colonization Affirmative •Mars Colonization Negative
2011 -> Asian Pacific Mathematical Olympiad(apmo)
2011 -> Registration Form (Rev. 8-86) omb no. 1024-0018

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