Welcome to Luciano Iess's Homepage

On the left: the JUNO mission (NASA) was launched on 5 agosto 2011 and it will orbit around Jupiter till 2021 and beyond. Its main purposes are the study of the atmosphere and the interior structure of the planet. Centre: artist view of the Cassini and Huygens probes at Saturn. Right: Saturn almost at equinox, as seen from Cassini (ISS Cassini).


**** Space Missions and Systems 2018/2019 - Homework #2:

The following students failed HW#2:

1618530 1555375 1593651 1645570 1694047 1836659 1851492 1879048

Homework#2 - Click here for full results.

Students marked with an asterisk (*) marginally passed the HW#2. This indicates a barely sufficient comprehension of the topics addressed in the problem. The (*) does not compromise access to the exam in "easy mode".

Students who wish to take the exam in June and did not pass both homeworks (or the Challenge and homework#2) must take the Multiple Choice Test tomorrow 5 June at 9:00.


Click here to download the test (NEW pdf file with the correct deadline).

The solution (a pdf file) and the source code must be emailed by Monday 3 June 23:59:59 to antonio.genova@uniroma1.it AND luciano.iess@uniroma1.it AND gael.cascioli@uniroma1.it AND ivan.distefano@uniroma1.it.


Suggestions and remarks: Be concise and go right to the point. Plots convey information very effectively. Including a working source code is mandatory. This is a pass/fail test.

Should you need clarifications, send an email to antonio.genova@uniroma1.it AND luciano.iess@uniroma1.it. We will answer only through the website.

We'll publish the results of those students who signed up for the 5 June exam by 17:00 Tuesday 4 June.


Important notice: resubmission of your homework will only be accepted if you provided a code that does not run, or if you missed some file in your email.



1) Should the s versor be defined as [-sin(psi) -cos(psi) 0] since the figure shows anti-clockwise positive angle? True. However, due to the symmetry of the spacecraft a desired psi or -psi angle provide the same results.

2) The maximum angular momentum is 7.5 Nms, but Iw*omegaw=0.01*7000rpm—> 7.33NmsFor consistency, consider Iw=0.01023.

3) The initial conditions at aphelion and perihelion are identical. The text is clear: "By assuming the previous conditions, address the following tasks when Mercury is at its aphelion (Ds=0.4) and perihelion (Ds=0.3)."

4) The angular velocity of the wheel is referred to inertial frame (IRF) or the body frame?The angular velocity of the wheels is measured onboard first in the body frame (optical or magnetic triggers can be used). Anyway, does this matter?

5) What is the tolerance on the target yaw angle? Use your judgement. When you feel that crucial data are missing, find reasonable values. Put yourself in the shoes of a spacecraft engineer. Why must the solar panels be tilted? Weigh the pros and cons of your choices.

6) The optional question is #7.

7) What is the required yaw angle after the desaturation maneuver has been completed? Again, use your judgement and, if in doubt, make a choice and motivate it. Presumably, the same reasons that required a certain yaw angle hold also after the completion of the maneuver. 


NEW: Latest version of the slides uploaded (28/5/2019)


NEW: Work and stage opportunities - see link on the left. (21/5/2019).


**** All exam dates are now on Infostud

**** Exams 3-5 June 2019


- 3 June 9:00 Space Environment MCT

Meet your professor in front of his office.

Exams will start at 9:45 and continue on 5 June.

You have to take this MCT if you wish to sign in for the 24 June oral exam. 


- 5 June 9:00 Space Missions and Systems MCT

Meet your professor in front of his office.

Exams will start at 9:45.

You have to take this MCT if you did not pass both homeworks and wish to take the oral exam on June 5 or 24 June.



**** Space Missions and Systems 2018/2019 - Challenge



2 points: Proietti, Musacchio

1 point: Leonardi, Tramutola, Collettini

Congratulations to the winners and all participants! There were many good solutions. My collaborators and I are very happy of the overall outcome, as the problem was not easy. Unfortunately nobody assigned the correct weights to the data, so the first prize (3 points) could not be awarded.

The challenge is a valid replacement for Homework #1 for:

Carfora, Coppola, Farisei, Ferrari, Giuliani, Lambertini, Lisi, Pianalto.

Please take note of the changes - (5 May 15:36) 


Challenge 2019 - download the zip file here.

Email a working computer code (Matlab is recommended) and a short note (a pdf file) with the mathematical procedure, results, comments, and figures by Monday 29 April 23:59:59 CET to luciano.iess@uniroma1.it AND gael.cascioli@uniroma1.it AND daniele.durante@uniroma1.it.

The challenge gives the opportunity to increase your grade at the exam:

Winner: +3 points 

Two second places: + 2 points 

Three third places: + 1 point 

It is highly instructive for everyone. I strongly recommend to give it a try.

The challenge is considered a valid replacement for Homework #1 if the first question is answered correctly. All students with  "Pass * " in Homework #1 must do it. Students with "Fail * " can try the challenge and gain points, but will not have access to the exam in simplified mode.


1) The MVE requested in the second question refers to the full data set, not just the first pass.


NEW: Fellowship opportunities in North America for master degree students (8/4/2019):



**** Space Missions and Systems 2018/2019 - Homework #1:


Students with ID 1716030, 1666591 and 1668227 passed Homework #1.

Click here to download the test (zip file). 

The solution (a pdf file) and the source code must be emailed by Wednesday  3 April 23:59:59 UTC to luciano.iess@uniroma1.it  AND gael.cascioli@uniroma1.it AND daniele.durante@uniroma1.it.  


Suggestions and remarks: Be concise and go right to the point. Plots convey information very effectively. Including a working source code is mandatory. This is a pass/fail test.

Should you need clarifications, send me an email. I will answer only through the website.


1) As explained on the side, the angle lambda_0 shown in the figure is arbitrary (generic).

2) How shall I treat the lack of continuity in the data (multiple emails)? Answer: Nobody can expect that tracking data are continuous in a real situation. Address the lack of continuity to the best of your knowledge.

3) Only upper limits are given on range and range rate (differently from previous homeworks). Answer: This should not be a problem, as we discussed many time how to find the real measurement accuracy and use it. (Obviously, homeworks are different from each other.)

4) "Compute and plot the orbital energy of the spacecraft orbit over time". We have not specified a time interval. It's your choice. Make it interesting!  



Please read the Exams section (link on the left) for important changes in the Multiple Choice Test (26 February 2018)








*** Plumbing the depth of Jupiter's winds 

Here is the link to the recent paper on Nature and some of its echoes in the news:

Iess et al. "Measurement of Jupiter's asymmetric gravity field", Nature, 555, 220-222 (2018)   

Nature Editorial

Nature Research highlights 


International coverage

NASA web site 

Scientific American (really good) 


New York Times 

Los Angeles Times 

Fox News 


America Space 

ABC News - MSN 

The Hindustan Times (India)

IFL Science 


Coverage in Italy


La Repubblica 

Le Scienze 

Il Tempo


Sapienza University of Rome



Challenge 2016-2017: Results

Benedicter 3 pt

Di Stefano 2 pt

Moscianese 2 pt

Cascioli 1 pt

De Grossi 1 pt

Frezza 1 pt

The challenge is considered as a valid replacement for HW#1 for Capozzi, Foschi, Kappers, and Trinca.

Congratulations to all participants! 


*** Short course on Matlab:  Download the full zip file here 

(This is all the material shown in both days).



Luciano Iess: "The Attraction of Gravity" - Jean Dominique Cassini Medal Lecture at the European Geosciences Union - Vienna, April 25, 2017. Video recording



*** New supporting material:

Matlab codes for batch and sequential estimation (spring-mass system) in Class Notes - Supporting Material


*** Second home test 2016 (updated lists!!):


Students admitted to the exam in fast mode


*** Challenge 2016 - Winners 

- Martini: 2 pt

- Cappuccio: 1 pt

Congratulations to all participants! 


*** An interesting link: Cassini behind the scenes


**** Space Missions and Systems

Matlab code for the coherent demodulator





For updated information you may follow me on Twitter (luciano_iess)


*** Seminars at Beijing Institute of Tracking and Telecommunications Technology (BITTT):

Seminar 1: Deep Space Navigation Systems: Where Do We Stand?

Seminar 2: The European Delta-DOR Correlator

Seminar 3: BepiColombo, the ESA Mission To Mercury; MORE: Geodesy, Geophysics, Navigation

Seminar 4 and 5: The Scientific Use of Deep Space Tracking Systems; Radio Science in Deep Space Missions

***Tour of Robledo's DNS facilities. The visit to the Robledo and Cebreros tracking complexes was an interesting and profitable experience for all of us. Follow the link to see some photos. 


Frequently Asked Question (FAQ)

Titan's Haze is Falling