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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! Lecture 12: Mars Odyssey 3
Citation preview
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!
Lecture 12: Mars Odyssey 3
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.
Lecture 12: Mars Odyssey 4
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.
Lecture 12: Mars Odyssey 5
Quiz #9
Lecture 12: Mars Odyssey 6
Quiz #9
Lecture 12: Mars Odyssey 7
Quiz #9
Lecture 12: Mars Odyssey 8
ASEN 5050SPACEFLIGHT DYNAMICS
Mars Odyssey
Prof. Jeffrey S. ParkerUniversity of Colorado - Boulder
Lecture 12: Mars Odyssey 9
ASEN 5050SPACEFLIGHT DYNAMICS
Launch
Prof. Jeffrey S. ParkerUniversity of Colorado - Boulder
Lecture 12: Mars Odyssey 10
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.
Lecture 12: Mars Odyssey12
Right Spherical Triangle
Lecture 12: Mars Odyssey13
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
Lecture 12: Mars Odyssey14
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.
Lecture 12: Mars Odyssey15
Launch AzimuthsLaunch sites and allowable azimuths
Lecture 12: Mars Odyssey16
Launch Sites
Lecture 12: Mars Odyssey17
Noncoplanar Transfers
Lecture 12: Mars Odyssey18
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.
Lecture 12: Mars Odyssey19
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.