Circular feature at Mars South Pole

[h2ouniverse]

Should be ok now<br />(it's image of the day at SDC so changes everyday).<br /><br />This link is dated:<br />http://www.space.com/imageoftheday/image_of_day_071019.html

 

[R1]

great, thanks.<br /><br />apparently it was first noticed back in the seventies!<br /><br />I think we need a multiplanetary explorer, one that we can move back and forth throughout the solar system as needed,<br />rather than sending one-way fly-by probes and waiting (wasting) all the time to build each one, for example a probe like<br /> distant horizons, or pioneer, or voyager that we could have kept a permanent, variable as needed solar orbit about the <br />size of Jupiter when not in use, at a 90 deg from the ecliptic.<br /><br />We could theoretically have had a pioneer or voyager in orbit all this time, fascilitating exploration as needed, <br />rather than building a new probe every 9 years we could simply steer it to go near the martian pole, and Io,<br /> Iapetus, the levy shoemaker spots, the martian face, our moon,<br /> (you name it, it could be there shortly like a police car on patrol),<br /> all kinds of multi planetary mappings, etc. It would have been the next best thing to being able to <br />steer the Hubble throughout the solar system for local (solar system) exploration.<br /><br />Doesn't this sound more cost effective and above all, extremely time efficient?<br /><br /><br /> <div class="Discussion_UserSignature"> </div>

 

[MeteorWayne]

"I think we need a multiplanetary explorer, one that we can move back and forth throughout the solar system as needed "<br /><br />That is just not realistic.<br /><br />No spacecraft can hold all the propellant required for such a scenario, and be affordable or launchable.<br /><br />Theory's fine, reality is a much tougher taskmaster.<br /> <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>

 

[h2ouniverse]

in reply to<br />---------Doesn't this sound more cost effective and above all, extremely time efficient?<br />------------<br /><br />Unfortunately no, it does not.<br />Orbital mechanics are awful. They say that planets orbit at different speeds around the sun. When you go from a planet to another, you need to adjust your speed accordingly, both tangentially and radially (vs Sun). Here we speak of differentials of tens of km/s (and that is neglecting yet the gravity wells of the planets). These are huge delta-v s. No launcher is able to launch the tens of tons of S/C that would be needed for such change-my-mind-when-I-want mission profiles.<br /><br />Combinations of fly-bys for gravity assit are planned in the phase A of missions. You cannot change your strategy late in the program.<br /> <br />If you really want reactivity you need either orbiters around each planet, or launching by-flyers towards the Outer System on a regular basis. But the budget is not there.

 

[michaelmozina]

<blockquote><font class="small">In reply to:</font><hr /><p>Hi all,<br /><br />Has anybody clues about this?:<br />http://www.space.com/imageoftheday/image_of_day_071019.html<br />In particular, does somebody know what the dark material in the depression is?<p><hr /></p></p></blockquote><br /><br />FYI, here is an "EU" explanation for that phenomenon.<br /><br />http://www.thunderbolts.info/tpod/2005/arch05/050830posnote.htm <div class="Discussion_UserSignature"> It seems to be a natural consequence of our points of view to assume that the whole of space is filled with electrons and flying electric ions of all kinds. - Kristian Birkeland </div>

 

[h2ouniverse]

thanks for the link.<br />But why a "European Union explanation"?