Lunar and Martian orbital "junk"?

[newtons_laws]

<p>As is well known, since the&nbsp;launch of Sputnik 1 over 50 years ago the Earth has now accumulated a large amount of orbital&nbsp;items, comprising both working and non functional satellites, rocket final stages&nbsp;and fragments of these that have exploded or collided with each other (some collisions being deliberate anti-satellite tests).&nbsp; The US tracks each of these thousands of objects and can give warning if a collision is due (and in the case of the ISS avoiding action is taken).</p><p>At least for the lower orbiting debris at a few hundreds of kms altitude above the&nbsp;Earth&nbsp;they will&nbsp;eventually disappear&nbsp;within a few centuries due to the residual atmospheric drag.&nbsp; However the thought occurred to me that since several countries have recently launched lunar orbiters, and the Martian exploration programme is thankfully steadily progressing<img src="http://sitelife.space.com/ver1.0/content/scripts/tinymce/plugins/emotions/images/smiley-cool.gif" border="0" alt="Cool" title="Cool" />, does anyone have any idea of how many items are now in Lunar and Martian orbit, and more pertinently, are their orbits all monitored to avoid collision with the new working orbiters?&nbsp; Since the Moon has no atmosphere, and Mars only has a very thin atmosphere any objects orbiting them may stay around for millions of years.</p><p>I recollect that during the Apollo missions some at least of the Saturn V 3rd stages after the TLI burn were on a course that meant they impacted the Moon (this was a useful event for the lunar seismometers positioned by earlier Apollo missions).&nbsp; I may be wrong, but I thought that in some cases after the ascent module of the LEM had returned the 2 lunar astonauts to the waiting Command and Service Module in lunar orbit and was jettisoned, it also was made to impact the lunar surface (if so how did they do this - remote control firing of the engine?).&nbsp; The recent ESA SMART-1 lunar satellite was deliberately crashed into the Moon at the end of its mission - perhaps this is a practice which should be adopted wherever possible for future automated missions to avoid the buildup of orbital "junk"<img src="http://sitelife.space.com/ver1.0/content/scripts/tinymce/plugins/emotions/images/smiley-smile.gif" border="0" alt="Smile" title="Smile" /></p><p>&nbsp;</p><p>&nbsp;</p> <div class="Discussion_UserSignature"> </div>

 

[MeteorWayne]

<p>Lunar orbits are not stable over centuries, but it would be inetersting to find a catalog of current orbiters and projected lifetimes in orbit.</p> <div class="Discussion_UserSignature"> <p><font color="#000080"><em><font color="#000000">But the Krell forgot one thing John. Monsters. Monsters from the Id.</font></em> </font></p><p><font color="#000080">I really, really, really, really miss the "first unread post" function</font><font color="#000080"> </font></p> </div>

 

[JonClarke]

Lunar orbits are not stable over a period of years and most lunar satellites have hit the surface. <div class="Discussion_UserSignature"> <p><em>Whether we become a multi-planet species with unlimited horizons, or are forever confined to Earth will be decided in the twenty-first century amid the vast plains, rugged canyons and lofty mountains of Mars</em>  Arthur Clarke</p> </div>

 

[JonClarke]

<p>The major objects in Mars orbit are:</p><p>Mars 2, Mars 3, Mars 5, Phobos 2, Mariner 9, Viking 1, Viking 2, Mars Global Surveyor,&nbsp; Mars Odyssey, Mars Express, Mars Reconniassance orbiter. Plus whatever debris they generated during their operation (ejected covers, bits of paint, insulation, lander separation debris from the Vikings). The older ones may have suffered explosions from residual propellants (remember they have been there more than 30 years).&nbsp; There might be a few bits from Mars Observer and Mars Climatology Orbiter, but we don't know if they entered orbit or not.</p> <div class="Discussion_UserSignature"> <p><em>Whether we become a multi-planet species with unlimited horizons, or are forever confined to Earth will be decided in the twenty-first century amid the vast plains, rugged canyons and lofty mountains of Mars</em>  Arthur Clarke</p> </div>

 

[newtons_laws]

<p><strong>JonClarke</strong>, Thanks for that info<img src="http://sitelife.space.com/ver1.0/content/scripts/tinymce/plugins/emotions/images/smiley-smile.gif" border="0" alt="Smile" title="Smile" />.&nbsp;Is the unstable nature of lunar orbits you and <strong>Meteor Wayne</strong> referred to&nbsp;due to the Earth making it a multi-body problem?&nbsp; The Martian orbiters are presumably in stable orbits?</p><p>Does anyone know if my recollection of some of the Apollo ascent modules being directed into the lunar surface after jettisoning is correct?</p> <div class="Discussion_UserSignature"> </div>

 

[JonClarke]

<p><BR/>Replying to:<BR/><DIV CLASS='Discussion_PostQuote'>JonClarke, Thanks for that info.&nbsp;Is the unstable nature of lunar orbits you and Meteor Wayne referred to&nbsp;due to the Earth making it a multi-body problem?&nbsp; </DIV></p><p>My understanding is that it is due to peturbations by mass concentrations (MASCONS) in the lunar crust.</p><p>Replying to:<BR/><DIV CLASS='Discussion_PostQuote'>The Martian orbiters are presumably in stable orbits?</DIV></p><p>I believe so.&nbsp; As on Earth, atmospheric drag will bring them down eventually.&nbsp; Maybe the oldest ones from 1971 (Mars 2, 3, Mariner 9) have already come down.</p><p>Replying to:<BR/><DIV CLASS='Discussion_PostQuote'>Does anyone know if my recollection of some of the Apollo ascent modules being directed into the lunar surface after jettisoning is correct? <br />Posted by newtons_laws</DIV></p><p>Nearly all of them&nbsp; were.</p><p>Jon<br /></p> <div class="Discussion_UserSignature"> <p><em>Whether we become a multi-planet species with unlimited horizons, or are forever confined to Earth will be decided in the twenty-first century amid the vast plains, rugged canyons and lofty mountains of Mars</em>  Arthur Clarke</p> </div>

 

[3488]

<p><BR/>Replying to:<BR/><DIV CLASS='Discussion_PostQuote'><font color="#ff0000">JonClarke, Thanks for that info.&nbsp;Is the unstable nature of lunar orbits you and Meteor Wayne referred to&nbsp;due to the Earth making it a multi-body problem?&nbsp; The Martian orbiters are presumably in stable orbits?Does anyone know if my recollection of some of the Apollo ascent modules being directed into the lunar surface after jettisoning is correct? <br /> Posted by newtons_laws</font></DIV></p><p><font size="2"><strong>Hi newtons_laws,</strong></font></p><p><font size="2"><strong>Lunar orbiters are subject to lunar MASCONs (MASs CONcentrations) in the lunar crust. The lanar gravity is not 100% the same everywher. The lunar greavity appears to be slightly weaker over the southern cratered highlands & also over much of the farside, but is stronger under much of the near side Maria, with some particular stronger points under Mare Tranquilitatis (Apollo 11's landing side) & Mare Crisium. This is due to dense volcanic lava filling in huge impact basins, thus leading to slighter stronger gravity in these areas.</strong></font></p><p><font size="2"><strong>I am not talking of many percent diffenrence, the varyation is literally a tiny portion of 1%, but is more than enough to play havoc with long term lunar orbiters.</strong></font></p><p><font size="2"><strong>Yes you are correct, the Apollo Lunar ascent stages did impact the moon post lift off once they did their jobs putting the crew members back into lunar orbit from the surface.</strong></font></p><p><font size="2"><strong>In fact the MasCons can make things a little tricky for landing craft as during decent they can be slighty tugged sidewise or slightly forward & backwards.</strong></font></p><p><font size="2"><strong>This appears to be far more of an issue than the multi body problem. The Moon, remember is quite a large & massive body, considerably more massive then the dwarf planets Eris & Pluto, both known to have their own moons (though they are very far from the Sun), quite far from Earth, so has it's own stable & coherent Hill Sphere.<br /></strong></font></p><p><font size="2"><strong>We know that the Moon is not alone with this. MESSENGER has found at least one MASCON with Mercury, Jupiter's Ganymede has at least two & the volcanic Jupiter moon Io has several. Venus & Mars do not seem to have such MASCONs, although Jon Clarke will know more.&nbsp;</strong></font></p><p><font size="2"><strong>Andrew Brown.&nbsp;</strong></font></p> <div class="Discussion_UserSignature"> <p><font color="#000080">"I suddenly noticed an anomaly to the left of Io, just off the rim of that world. It was extremely large with respect to the overall size of Io and crescent shaped. It seemed unbelievable that something that big had not been visible before".</font> <em><strong><font color="#000000">Linda Morabito </font></strong><font color="#800000">on discovering that the Jupiter moon Io was volcanically active. Friday 9th March 1979.</font></em></p><p><font size="1" color="#000080">http://www.launchphotography.com/</font><br /><br /><font size="1" color="#000080">http://anthmartian.googlepages.com/thisislandearth</font></p><p><font size="1" color="#000080">http://web.me.com/meridianijournal</font></p> </div>

 

[3488]

<p><BR/>Replying to:<BR/><DIV CLASS='Discussion_PostQuote'><font color="#ff0000">My understanding is that it is due to peturbations by mass concentrations (MASCONS) in the lunar crust.I believe so.&nbsp; As on Earth, atmospheric drag will bring them down eventually.&nbsp; Maybe the oldest ones from 1971 (Mars 2, 3, Mariner 9) have already come down.Nearly all of them&nbsp; were.Jon <br /> Posted by jonclarke</font></DIV></p><p><font size="2"><strong>Hi Jon,</strong></font></p><p><font size="2"><strong>Good point, IIRC Mariner 9 was expected to hold up for about 50 years, before deorbiting? So that would be approx November 2021.</strong></font></p><p><font size="2"><strong>Dunno about Mars 2 or Mars 3 though. I would expect similar.</strong></font></p><p><font size="2"><strong>Andrew Brown.&nbsp;</strong></font></p> <div class="Discussion_UserSignature"> <p><font color="#000080">"I suddenly noticed an anomaly to the left of Io, just off the rim of that world. It was extremely large with respect to the overall size of Io and crescent shaped. It seemed unbelievable that something that big had not been visible before".</font> <em><strong><font color="#000000">Linda Morabito </font></strong><font color="#800000">on discovering that the Jupiter moon Io was volcanically active. Friday 9th March 1979.</font></em></p><p><font size="1" color="#000080">http://www.launchphotography.com/</font><br /><br /><font size="1" color="#000080">http://anthmartian.googlepages.com/thisislandearth</font></p><p><font size="1" color="#000080">http://web.me.com/meridianijournal</font></p> </div>

 

[tanstaafl76]

<p>&nbsp;</p><p>I'm waiting for Waste Management to launch a Garbage Scow into space and start charging the planet up the ying-yang to clean up LEO! </p> <div class="Discussion_UserSignature"> </div>