ASEN 5050 SPACEFLIGHT DYNAMICS Mars Odyssey Prof. Jeffrey S. Parker University of Colorado Boulder...

ASEN 5050SPACEFLIGHT DYNAMICS

Mars Odyssey

Prof. Jeffrey S. ParkerUniversity of Colorado – Boulder

Lecture 12: Mars Odyssey 1

Announcements• Homework #4 is due right now

• Homework #3 is re-active. Submit a new HW3 submission to the Dropbox or in person by Friday 10/3! – CAETE by Friday 10/10– You can recover ½ of the points you lost, or get a 90%, whichever is

higher.

• Mid-term Exam will be handed out Friday, 10/17 and will be due Wed 10/22. (CAETE 10/29)– Take-home. Open book, open notes.– Once you start the exam you have to be finished within 24 hours.– It should take 2-3 hours.

• Reading: Chapter 6Lecture 12: Mars Odyssey 2

Grading

• Homework grading– Tough. We’re dropping points pretty easily.

• Units• Work• Not answering questions

– This is a graduate course, so it takes pretty good work to get an A. At a minimum, you need to read the questions and provide answers to what we’re asking.

– This class will ultimately be graded on a curve of some sort. It’s soooo much easier to give everyone a better grade than to knock everyone down at the end!


HW3

• I’m posting the solutions online now.

• If you missed anything, go redo it until your answers match the online solutions.

• If you do, we’ll give you half of your points back, or a 90, whichever is higher.


D2L

• Request:– Please submit your answers in a Word Doc or a PDF– It’s fine to include code in a .zip file, but it’s harder to

grade the HW if the HW is also included in the .zip file.


Quiz #9



Mars Odyssey

Prof. Jeffrey S. ParkerUniversity of Colorado - Boulder



Launch

Prof. Jeffrey S. ParkerUniversity of Colorado - Boulder


Lecture 12: Mars Odyssey11

Launch

Launching a satellite:

For a direct launch, the launch site latitude must be less than or equal to the desired inclination, otherwise we must change the inclination of the orbit.


Right Spherical Triangle


We can show this using spherical trigonometry for a right spherical triangle (eq. C-23):

Thus,

Because |sin | ≤ 1, the launch latitude gc ≤ i

Another useful relation: sin gc = sin(i) sin(+)

Launch

Cannot direct launch into orbit with inclination < gc


Launch

The launch site velocity is:

Note all the velocity is Eastward in the SEZ system, so launching from the equator on a 90 azimuth may be best.

The velocity at the equator is vL = 0.465 km/s. Westward launches must make this up, so difference is 0.93 km/s.


Launch AzimuthsLaunch sites and allowable azimuths


Launch Sites


Noncoplanar Transfers


Noncoplanar TransfersLaunch window – select UT to achieve orbit’s desired

initial nodal location (determine gst)

First determine launch azimuth (inverse sine gives two possible answers: and 180-, for ascending (-90 < u < 90) and descending (90 < u < 270) passes.)

Now, determine the auxiliary angle from:

The values u and 360-u represent prograde and retrograde orbits respectively.


Noncoplanar Transfers

Tolerance on ascending node (±) creates “launch window”, or range of values of GST. Once GST is chosen:

Substitution of GST0 for each day (GST at 0 hrs on that day) gives the launch time on each day.

v is more complicated.

ASEN 5050 SPACEFLIGHT DYNAMICS Mars Odyssey Prof. Jeffrey S. Parker University of Colorado Boulder...

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