<div dir="ltr"><div dir="ltr"><div dir="ltr"><div class="gmail_quote"><div dir="ltr" class="gmail_attr">On Wed, 18 Dec 2024 at 20:54, Adrian Tymes via extropy-chat <<a href="mailto:extropy-chat@lists.extropy.org" target="_blank">extropy-chat@lists.extropy.org</a>> wrote:<br></div><blockquote class="gmail_quote" style="margin:0px 0px 0px 0.8ex;border-left:1px solid rgb(204,204,204);padding-left:1ex"><div dir="ltr"><div class="gmail_quote"><div></div><div>What would it take to nudge Apophis from "might impact Earth later" into a stable orbit around the Earth, or perhaps the Moon (and thus around the Earth)? </div></div></div>
_______________________________________________<br></blockquote><div><br></div><div style="font-family:arial,sans-serif;font-size:small;color:rgb(0,0,0)" class="gmail_default"><br></div><div style="font-family:arial,sans-serif;font-size:small;color:rgb(0,0,0)" class="gmail_default"><br></div><div style="font-family:arial,sans-serif;font-size:small;color:rgb(0,0,0)" class="gmail_default">Perplexity AI thinks it is an impossible task.</div><div style="font-family:arial,sans-serif;font-size:small;color:rgb(0,0,0)" class="gmail_default">BillK</div><div style="font-family:arial,sans-serif;font-size:small;color:rgb(0,0,0)" class="gmail_default"><br></div><div style="font-family:arial,sans-serif;font-size:small;color:rgb(0,0,0)" class="gmail_default">Perplexity AI -<br></div><div style="font-family:arial,sans-serif;font-size:small;color:rgb(0,0,0)" class="gmail_default">To slow Apophis enough to enter Earth's orbit would be an extremely challenging and potentially dangerous endeavor. Apophis is a large asteroid with an estimated mass of 6.1×10^10 kg[1]. Altering its trajectory significantly would require an enormous amount of energy and precise calculations. Here's an analysis of what would be theoretically required:<br><br>## Orbital Mechanics<br><br>Apophis currently has an elliptical orbit around the Sun with a period of about 0.89 years[1][2]. To capture it into Earth orbit, we would need to:<br><br>1. Reduce its velocity relative to Earth<br>2. Change its trajectory to intersect with Earth's gravitational sphere of influence<br>3. Apply additional deceleration to prevent it from escaping Earth's gravity<br><br>## Energy Requirements<br><br>The change in velocity (Δv) required would be substantial:<br><br>1. Apophis has an average orbital speed of 30.73 km/s[1]<br>2. Earth's orbital velocity is approximately 29.78 km/s<br>3. The Δv needed would be on the order of several km/s, depending on the exact capture scenario<br><br>Given Apophis's large mass, the energy required for such a maneuver would be enormous, far exceeding our current technological capabilities.<br><br>## Potential Methods<br><br>While not feasible with current technology, theoretical approaches might include:<br><br>**Enhanced Kinetic Impactor (EKI)**<br>An EKI could potentially be used to slow Apophis, but it would require:<br>- Collecting hundreds of tons of rock from a Near-Earth Asteroid<br>- Multiple impacts to achieve the necessary Δv[5]<br><br>**Gravity Tractor**<br>A massive spacecraft could use gravitational attraction over an extended period to alter Apophis's trajectory[3]. However, this method is too slow and weak for the drastic changes required for orbital capture.<br><br>**Laser Ablation**<br>High-powered lasers could vaporize surface material, creating thrust to slow the asteroid[4]. This would require an enormous space-based laser array, far beyond our current capabilities.<br><br>**Ion Beam Deflection**<br>A powerful ion engine could theoretically provide continuous thrust[3], but the scale required for Apophis would be impractical with current technology.<br><br>## Risks and Challenges<br><br>Attempting to capture Apophis into Earth orbit would be extremely risky:<br><br>1. Any miscalculation could potentially direct Apophis towards Earth, causing catastrophic damage.<br>2. The close proximity required for such maneuvers would put Earth at risk.<br>3. Even if captured, stabilizing Apophis in Earth orbit would be an ongoing challenge.<br><br>## Conclusion<br><br> asteroids away from Earth rather than capturing theWhile theoretically possible, slowing Apophis enough to enter Earth 
orbit is far beyond our current technological capabilities and would be 
extremely dangerous. The energy requirements are enormous, and the risks
 far outweigh any potential benefits. Current planetary defense 
strategies focus on deflecting potentially hazardousm[3][4].<br><br>Citations:<br>[1] <a href="https://en.wikipedia.org/wiki/99942_Apophis" target="_blank">https://en.wikipedia.org/wiki/99942_Apophis</a><br>[2] <a href="https://science.nasa.gov/solar-system/asteroids/apophis/" target="_blank">https://science.nasa.gov/solar-system/asteroids/apophis/</a><br>[3] <a href="https://newspaceeconomy.ca/2024/06/02/defending-earth-strategies-for-deflecting-hazardous-asteroids/" target="_blank">https://newspaceeconomy.ca/2024/06/02/defending-earth-strategies-for-deflecting-hazardous-asteroids/</a><br>[4] <a href="https://www.planetary.org/articles/asteroid-deflection-techniques-to-save-the-earth" target="_blank">https://www.planetary.org/articles/asteroid-deflection-techniques-to-save-the-earth</a><br>[5] <a href="https://pmc.ncbi.nlm.nih.gov/articles/PMC7244770/" target="_blank">https://pmc.ncbi.nlm.nih.gov/articles/PMC7244770/</a><br>[6] <a href="https://nss.org/technologies-for-asteroid-capture-into-earth-orbit-2/" target="_blank">https://nss.org/technologies-for-asteroid-capture-into-earth-orbit-2/</a><br>[7] <a href="https://www.spacereference.org/asteroid/99942-apophis-2004-mn4" target="_blank">https://www.spacereference.org/asteroid/99942-apophis-2004-mn4</a><br>[8] <a href="https://www.aanda.org/articles/aa/full_html/2014/03/aa22364-13/aa22364-13.html" target="_blank">https://www.aanda.org/articles/aa/full_html/2014/03/aa22364-13/aa22364-13.html</a><br>[9] <a href="https://space.stackexchange.com/questions/59212/how-could-99942-apophis-in-2029-be-captured-and-brought-into-a-low-earth-orbit" target="_blank">https://space.stackexchange.com/questions/59212/how-could-99942-apophis-in-2029-be-captured-and-brought-into-a-low-earth-orbit</a><br>[10] <a href="https://www.esa.int/Space_Safety/Planetary_Defence/Apophis" target="_blank">https://www.esa.int/Space_Safety/Planetary_Defence/Apophis</a></div><div style="font-family:arial,sans-serif;font-size:small;color:rgb(0,0,0)" class="gmail_default">------------------------------------<br></div></div></div>
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