Asteroid Affirmative

Download 0.74 Mb.
Date conversion29.04.2016
Size0.74 Mb.
1   ...   43   44   45   46   47   48   49   50   ...   66


Space Based Detection Key

Space based infrared detection technologies are accurate and fast

NASA ’06 (“2006 Near Earth Object Survey and Reflection Study”, Nasa Office of Program Analysis and Evaluation, Pg. 34, December 28, 2006,, TDA)

With the exception of technology maturity, space-based infrared systems have the same advantages as space-based optical systems. For infrared systems this technology is maturing rapidly. Space-based, passively cooled infrared systems also have additional advantages. They require smaller apertures than optical systems of equal detection efficiency and provide more accurate estimates of object sizes. The object size uncertainties are less than 50% compared with 230% for visual detectors. A two-band infrared system could lower the size uncertainties to about 20%. These space-based systems also are much less affected by the problem of source confusion. There are about 100 times fewer infrared sources per square degree at an infrared wavelength of 8 microns compared with the number of visible sources at 0.5 microns. In addition, space based infrared systems have lower downlink data rate requirements than space-based visible detector systems. Space-based infrared systems were the most capable (sensitive) of the alternatives considered.

Space Based Detection Key

Space based detection key - Earth Based optical systems are inaccurate and ineffective

NASA ’06 (“2006 Near Earth Object Survey and Reflection Study”, Nasa Office of Program Analysis and Evaluation, Pg. 34, December 28, 2006,, TDA)

Because these optical systems must view through Earth's atmosphere, ground systems have drawbacks. Ground-based optical systems cannot operate during daylight or twilight and are subject to interference from weather, atmospheric turbulence, scattering from moonlight, and atmospheric attenuation. These systems cannot easily operate close to the galactic plane because atmospheric turbulence and scattering cause source confusion. Significant atmospheric attenuation in the infrared-spectral region prevents these systems from accurately determining NEO sizes. These systems also will have difficulty finding objects in inner-Earth or Earth-like orbits. They have fewer discovery opportunities because they are available only at the beginning and end of each night. Additionally, ground-based systems have intangible programmatic issues related to site and infrastructure maintenance. These issues are made worse if the telescopes are sited on foreign territory to achieve the best observing conditions and operate for decades.

Transponders are necessary to track asteroids because radar is limited to near-earth distances.

Bucknam, Mark and Robert Gold in 8 (Former Council Military Fellow, Survival, Asteroid Threat? The Problem of Planetary Defence,, DF)

Though radar telescopes, such as the giant 305m dish at Arecibo, Puerto Rico, enable rapid and accurate assessments of PHO size and orbit, they are only useful when the objects pass within a few million kilometres of Earth. NASA recommended against developing a radar specifically for finding and tracking PHOs, stating that ‘orbits determined from optical data alone will nearly match the accuracy of radar-improved orbits after one to two decades of observation’. 15 Existing radar telescopes should be used as far as possible to refine predictions of Apophis’s trajectory – either confirming or ruling out the potential for an impact in 2036. In addition to fielding new Earth- and space-based sensors as suggested by NASA, former astronaut Rusty Schweickert called for placing a transponder on Apophis during a close approach in 2013 to help determine whether a 2036 collision is likely. 16 This could save years of worrying, or give us extra years to prepare and act. Such a mission would cost on the order of a few hundred million dollars.

Space Based Detection Key

Space based detection key – it’s more effective and circumvents glare

Rather et. al 2010 (John Rather is a former assistant director for NASA, founder of Rather Creative Innovations Group, James Powell, George Maise, AIP Conference Procedings, “New Technologies and Strategies to Exploit Near Earth Asteroids for Breakthrough Space Development”, January 28 2010, Vol. 1208 Issue 1, pg. 566-570, EBSCOhost, TDA)

If advantageous use is to be made of ten-meter-class objects, much better ways must be implemented to find them and react to their approach in real time. The first step is to develop specialized detection systems to extend the complete census of these small, very faint objects down to ten-meter diameters. Present NEO discoveries and orbital determinations are mostly made by nighttime observations from the Earth’s surface. Small objects having semi-major axes less than one AU spend much time closer to the sun than the Earth and thus have a significant bias against discovery by Earth-based observations. While present automated search methods will eventually catalog most NEOs having diameters larger than 30 meters, an efficient and inexpensive method is needed to extend the complete census to the much more numerous smaller objects. The required system must also address the problem of finding the largely unknown population that remains lost in the sun’s glare. Space-based optical/infrared methods will remain the primary initial discovery tools of very small NEOs, but radar also has important roles for identifying both useful and/or hazardous objects. All-sky, “24-7” radar searches are not practical because of inverse fourth power signal attenuation characteristic of radar transmission and reflection. Relatively large transmitting/receiving apertures are required to attain adequate signal-to-noise at ranges of tens of millions of kilometers, but the associated narrow beams make whole-sky 4 steradian searches expensive and time consuming. Many small objects would pass undetected without a very large number of dedicated radars. If the initial discoveries are efficiently made by space-based optical/infrared methods, however, handoff to a few dedicated radars on the Earth can then perform the vital functions of precision tracking, imaging, geological appraisal, and management of spacecraft rendezvous dynamics. With all of the above constraints in mind, we propose a near-term, relatively low cost but highly efficient combination of detection technologies as the first step to exploitation of small ten-meter class NEOs. This combination consists of a small spacecraft equipped with a scanning wide-field optical/infrared surveillance telescope located at the sun/earth L2 Lagrange region near the tip of the Earth’s shadow (a similar location to the James Webb telescope but no threat to it), and three 12-meter aperture millimeter-wavelength radars situated in appropriate locations around the Earth to enable full-time, whole-sky access on short notice. The shadowed spacecraft can efficiently cover 4[pi] steradians every six hours. The primary function of the spacecraft is to hand-off each discovery to the radar system while the NEO is still about twenty million kilometers from the Earth. Synergistically, the spacecraft will also identify high-velocity dangerous objects coming from the direction of the sun. The requisite spacecraft and radars are completely within the existing states-of-the art, and the entire system should be realizable within four years for a cost of less than $200 million. A study should also be performed soon to investigate whether early deployment of the radars alone could work effectively in combination with existing space assets such as the Wide-field Infrared Survey Explorer (WISE) mission. The latter very low-cost strategy might expedite near-term initiation of the complete census of ten-meter diameter NEOs.

1   ...   43   44   45   46   47   48   49   50   ...   66

The database is protected by copyright © 2016
send message

    Main page