Why launch upside down?

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thereiwas

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In photos of Mars landers being assembled onto their launch vehicles, they seem to always be upside down, with the re-entry heat shield facing forward. Is there some reason for this other than it makes you arrive at Mars in the correct orientation?<br /><br />It seems to me it would be easier to design the lander to only have to survive high acceleration and jolts coming from one direction if they launched upright.
 
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3488

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The lander will be upside down. When the lander enters the<br />Martian atmosphere, the heatshield needs to be in the direction of travel, & will be facing <br />downward,hence the lander will then be upright.<br /><br />The heatshield during interplanetary cruise is also facing forward.<br /><br />You might be interested in these graphics of Mars Pheonix Lander.<br /><br />Phoenix in Cruise.<br /><br />Phoenix Cruise Stage being Jetissoned.<br /><br /> Phoenix just prior to atmospheric entry.<br /><br />Phoenix atmospheric entry.<br /><br />NASA / JPL.<br /><br />Hope these help?<br /><br />Andrew Brown. <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>
 
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bpcooper

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Facing direction of travel is irrelevant as they could turn it if needed.<br /><br />If the heatshield were facing down on the rocket, how would they secure it to the third stage? Not quite as easily. That's the main reason. <div class="Discussion_UserSignature"> <p>-Ben</p> </div>
 
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3488

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Hi Ben,<br /><br />Yes that's true, but IMO if the craft was already in the correct direction of travel<br />post launch anyway, than the need for turning the craft around is not needed, one<br />less post launch maneuver to have to worry about.<br /><br />Just my thought.<br /><br />Andrew Brown. <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>
 
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rybanis

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I think Cooper has the right idea. Besides the craft is oriented away from the direction of travel during most of the flight anyways, to get sunlight on the solar panels. <div class="Discussion_UserSignature"> </div>
 
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h2ouniverse

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Yes. When designing a shield, avoid making holes in it!! (e.g. for a launcher interface...)
 
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thereiwas

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Since Mercury, Gemini, and Apollo all launched shield-down, they must have figured out solutions to the connection problems.
 
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bpcooper

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Those capsules were outside the rocket, on a rocket modified or designed specifically for their mission. Not quite like a Mars lander on an ELV today.<br /><br />Anyway, I was just answering his question. It is the main reason they do not launch the Mars missions with the rover/heatshield down on the rocket. <div class="Discussion_UserSignature"> <p>-Ben</p> </div>
 
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h2ouniverse

Guest
There is no way to put a shield down when designing a S/C for Ariane, or Soyuz... when the launcher interface is a ring, and not discrete points. Unless you design a specific adapter => cost + mass
 
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thereiwas

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How about a cruise stage that mates to the LV ring, and the lander is above that? Then the special adaptation to the shell is the job of the cruise stage, not the LV. Don't most Mars missions come in two parts, one that handles the enroute course corrections, has the solar panels, and then the lander separates just before reentry?
 
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jimfromnsf

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Most mars entry vehicles are passive and have no thrusters for orientation. Therefore it is the cruise stage's job to provide the orientation. It does it from the aft so that :<br />1. The attachment is on the back shell and not on the <br />heatshield. <br /><br />2. heatshield shape is not constrained for an attachment to the cruise stage<br />2. When the cruise stage is jettison, it is out of the way<br /><br /><br /> Ben is right
 
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