asen 5050 spaceflight dynamics mars odyssey prof. jeffrey s. parker university of colorado boulder...
DESCRIPTION
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 3TRANSCRIPT
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.