Galileo / Magellan Deployments

[backspace]

I seem to remember a post somewhere before the crash that mentioned that following the Challenger accident, boost stages for satellites on board the shuttle had been nixed. But, since Magellan and Galileo were POST Challenger, did they employ a different type of stage that was deemed safe, or was it simply too late to redesign the missions, and these were "the last two?"<br /><br />Also, what exactly is a PAM-D?

 

[alexblackwell]

<i>I seem to remember a post somewhere before the crash that mentioned that following the Challenger accident, boost stages for satellites on board the shuttle had been nixed. But, since Magellan and Galileo were POST Challenger, did they employ a different type of stage that was deemed safe, or was it simply too late to redesign the missions, and these were "the last two?"</i><br /><br />Yes, both Magellan and Galileo were slated pre-Challenger disaster to utilize the Centaur G-Prime upper stage and deployed by the shuttle. Post-Challenger, both probes switched to the "safer," and less powerful, solid-fueled IUS upper stage, which necessitated changes in their respective trajectories.<br /><br />Note, though, that Galileo's choice of upper stages varied throughout its turbulent pre-launch period as the mission was redesigned repeatedly.<br /><br /><i>Also, what exactly is a PAM-D?</i><br /><br />The Payload Assist Module (PAM) is a solid-fueled upper stage.

 

[backspace]

I noticed on the FAS site that there were only a few IUS acquisitions remaining (in 2003). Is there a replacement for IUS in existence or planning? I saw a sheet from 2002 talking about the "AUS" or Advanced Upper Stage.<br />It appeared to be in early development at the time that document was being written...<br />

 

[najab]

><i>Is there a replacement for IUS in existence or planning?</i><p>No. And with the imminent Shuttle retirement, there won't be.</p>

 

[backspace]

Ok. Now, the shuttle retreived at least 3 satellites that had failures with the PAM-D and had brought them back down to Earth. Wasn't this a bit risky bringing the stages back on board with the propellant? Or were the PAM-D's detatched during EVA? Even getting the shuttle close to one of those seems risky to me.<br />

 

[najab]

><i>Wasn't this a bit risky bringing the stages back on board with the propellant?</i><p>Not really, solid motors generally are fairly safe once the firing circuits are inactivated. It takes a lot more than a stray spark to light them, usually there is an explosive device involved.</p>

 

[CalliArcale]

In fact, anytime you send something up in the Shuttle, you have to be okay with the idea of bringing it back that way too -- in case the mission is aborted very early. Solids are considered safer for this purpose than liquids.<br /><br />I believe the last Shuttle-deployed IUS was used to boost Chandra into its optimal orbit. There are several copies of a lovely poster showing Chandra drifting off into the blackness posted around my workplace. The IUS is clearly visible -- and is actually more visible than Chandra, since Chandra is mostly black, and the IUS is mostly white. <div class="Discussion_UserSignature"> <p> </p><p><font color="#666699"><em>"People assume that time is a strict progression of cause to effect, but actually from a non-linear, non-subjective viewpoint it's more like a big ball of wibbly wobbly . . . timey wimey . . . stuff."</em>  -- The Tenth Doctor, "Blink"</font></p> </div>