MSL will use the Deep Space 1 navigation system?

[willpittenger]

I saw this the page http://marsprogram.jpl.nasa.gov/msl/mission/sc_cruise.html: "Mars Science Laboratory would use the stars to navigate. An onboard star scanner would keep the cruise stage on track by constantly monitoring its position relative to stars in our Milky Way galaxy."<br /><br />Did the Deep Space 1 navigation system finally reach production space craft? If so, should something like what killed Mars Climate Orbiter (failed when we entered bad data) happen again, I would expect MSL to adjust course to fix the problem on its own. It would "learn". <div class="Discussion_UserSignature"> <hr style="margin-top:0.5em;margin-bottom:0.5em" />Will Pittenger<hr style="margin-top:0.5em;margin-bottom:0.5em" />Add this user box to your Wikipedia User Page to show your support for the SDC forums: <div style="margin-left:1em">{{User:Will Pittenger/User Boxes/Space.com Account}}</div> </div>

 

[spacechump]

I believe a star trackers were on the MER busses as well as on the Pathfinder bus.<br /><br />MRO does<br /><br />And so did Smart-1<br /><br />I can't find a whole lot on it but Wiki has an article on altitude control and I'm pretty sure this has been used for years and years. They may have given the system more autonomy but I don't think the system is relatively special in any sense.

 

[mrmorris]

<font color="yellow">"They may have given the system more autonomy but I don't think the system is relatively special in any sense. "</font><br /><br />DS-1 did have an experimental autonomous navigation system onboard. I found at least one link that indicated the star tracker was <b>not</b> part of AutoNav, but was simply part of the attitude control system. In any event -- AutoNav and star trackers are not synonymous. However -- I didn't see anything in the initial MSL article that indicated an AutoNav system was being included. I may have missed it, mind you...

 

[spacechump]

<i>DS-1 did have an experimental autonomous navigation system onboard. I found at least one link that indicated the star tracker was not part of AutoNav, but was simply part of the attitude control system. In any event -- AutoNav and star trackers are not synonymous. However -- I didn't see anything in the initial MSL article that indicated an AutoNav system was being included. I may have missed it, mind you...</i><br /><br />I knew that much about DS-1. In fact there was a great special on the Science Channel that outlined AutoNav. I too cannot find any references to AutoNav on MSL. In any case a star tracker itself should be sufficient for attitude tracking because the trajectories to Mars are usually pretty precise.

 

[mrmorris]

<font color="yellow">"...a star tracker itself should be sufficient for attitude tracking because the trajectories to Mars are usually pretty precise."</font><br /><br />Just to be clear -- star trackers are used for attitude determination -- namely to determine the 3-axis direction the spacecraft is facing. The AutoNAV functionality on DS-1 was used for Navigation -- namely to determine where the spacecraft is in relation to its end goal, decide whether it is on a valid trajectory to reach it, and if not, calculate when to fire the thrusters, what direction to fire them in, and for how long. The star tracker might be *used* by the AutoNav -- specifically when determining what direction the spacecraft is facing for thruster pointing, but they do not act as a navigation system on their own.<br /><br />Star trackers are very very common on modern spacecraft. DS-1 is the only craft I'm aware of that had an automated navigation system.

 

[unclefred]

The description on the JPL web site "Mars Science Laboratory would use the stars to navigate. An onboard star scanner would keep the cruise stage on track by constantly monitoring its position relative to stars in our Milky Way galaxy." is wrong. It is not possible to navigate (adjust one's orbital trajectory) by looking at the stars. The change in any star's position due to the observer's position in the solar system is extremely small. Measuring the star position change due to a motion of the entire diameter of the Earth's orbit is difficult for even big telescopes. The stars look the same from Mars as they do from Earth. The JPL web site is just plane wrong.<br /><br /> They may be attempting to say that they are going to keep the spacecraft oriented by using the stars. In other words, 3 axis stable. Previous JPL Mars missions have been spin stabilized so they may think it is worth mentioning, even though this is a common technique and was used on Mars Odyssey and MRO and lots of other spacecraft. <br />

 

[unclefred]

It turns out that MSL is a spinner and the star sensor cannot possibly do the navigation. I suspect that it is just a poor choice of words done by some non-technical type. Navigation for all the course correction burns will be probably be done the same as before using ground based techniques.

 

[flynn]

I believe Columbus, Drake and Nelson all used the same system. <div class="Discussion_UserSignature"> <font color="#800080">"All God does is watch us and kill us when we get boring. We must never, ever be boring" - <strong>Chuck Palahniuk</strong>.</font> </div>