COURSE PROJECT
MAE 5091: Space Environment
Fall 2008
NOTE: You will need to gain access to the following website to complete this project:
http://www.spenvis.oma.be/intro.html Follow the link on the left side of the screen
labeled “Register”. You will be given a username and password after some verification.
Do this early so that there are no issues with access to the models for your project. The
project deadline will not change due to access issues so deal with this early.
1. Briefly describe the MSISE-00 and IRI-2001 models. Describe in terms of the
following parameters: data used to develop the model, parameters used to obtain
relevant results, assumptions and limitations of the model, and accuracy of the results
obtained. This will require a literature search.
2. Using the MSISE-00 model, plot the total mass density of the upper atmosphere from
200 to 1000 km altitude for F10.7 = 140 sfu and Ap = 15 nT. Plot the same parameter for
F10.7 = 220 sfu and Ap = 15 nT. How does the total mass density as a function of
altitude change with the F10.7 flux?
3. Using the IRI-2001 model, plot the electron, ion and neutral temperatures as a
function of F10.7 flux at 350 km altitude. Is the plasma at this altitude in local thermal
equilibrium? Is the plasma quasi-neutral?
4. Using the “Atmosphere and Ionosphere” models in the SPENVIS package, calculate
the atomic oxygen number flux (per unit area) to a ram facing surface on a spacecraft at
350 km altitude. Assume F10.7 = 140 sfu and Ap = 15 nT. How does this number
compare to what you would calculate using the notes (Eq. 81 and Fig. 25)?
PROJECT:
A satellite was launched in January 2002. The spacecraft was launched into a circular
orbit with an altitude of 350 km. The orbital inclination is 28.4◦. Assume that the
satellite geometry is the same as that in Homework #3, Problem #1 and that the surface
interaction is specular. Utilize the plots below for key parameters. Characterize the
environment using the MSISE-00 code.
A. Calculate the drag on the spacecraft after its initial orbit has been established.
B. From the drag force, calculate the change in the spacecraft’s initial altitude after the
first day on orbit. You can assume the drag force calculated is constant for the day.
C. Using the nominal prediction, estimate the lifetime of the spacecraft if it were
launched in January 2002. Assume that the spacecraft has re-entered at an altitude of 100
km. Hint: Calculate the delta-V during some timestep. Justify the timestep you use.
This delta-V will lead to a new altitude for the spacecraft. Iterate.
D. Compare the previous result to that estimated by the following eqn. where lifetime is:
H
; and B  m / CD A , H is the atmospheric scale height (=54.8 km), A is
L
( 2B 1 a 2 )
the satellite cross sectional area (normal to the ram direction), is the atmospheric
density, and a is the orbital radius (as measured from the center of the Earth for a circular
orbit). Assume the satellite mass is 300 kg.
E. Using the MSISE-00 model calculate the drag on the spacecraft if it were launched in
January 2004 assuming i.) nominal prediction of F10.7 cm flux, ii.) maximum prediction
of F10.7 cm flux, iii.) minimum prediction of F10.7 cm flux. Comment on the expected
lifetime depending on the solar conditions at which launch occurs.
How much additional propellant would be required for drag makeup if the maximum
condition prevails over the nominal condition? Assume that the dry mass of the
spacecraft is 300 kg and a typical chemical thruster (Isp=240 sec) is used.
F. Mission planners have come to you for an assessment of environmental issues on
spacecraft if it were placed in a polar orbit of the same height. Using the tools available
to you, provide this assessment.
G. Mission planners are now considering a semi-synchronous, equatorial orbit and need
an assessment of environmental issues on the spacecraft. Using the tools available to
you, provide this assessment.