1618530 1555375 1593651 1645570 1694047 1836659 1851492 1879048

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.

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.

NO EXCEPTIONS!

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.

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.

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.

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.

**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.

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

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.

NO EXCEPTIONS!

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!

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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)

** **

**International coverage**

Scientific American (really good)

The Hindustan Times (India)

**Coverage in Italy**

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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!**

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

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

Students admitted to the exam in fast mode

- Martini: 2 pt

- Cappuccio: 1 pt

**Congratulations to all participants!**

Matlab code for the coherent demodulator

**___________________________________________________________ **

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

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.

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*Titan's Haze is Falling*