ESA Document - Emits - ESA

s
Configuration Length
(m)
Total mass
(tonnes)
Total length
(m)
Comp CoG
(m)
Inertia total
kg*m^2/1000
MEV 10 46 10 5.0
THM 19 65 29 13.5
ERC 0 15 29 15.3 22874
TEI 15 160 44 27.2 63444
MOI 0 100 44 31.5 84414
TMI 3rd 15 249 59 39.4 172759
HMM
Assessment Study
Report: CDF-20(A)
February 2004
page 193 of 422
Table 3-36: TMI 3 rd dimensions
The ACS functions shall be:
• Attitude control while cruising to Mars
• Manoeuvres
• Rate dumping after TMI 2nd stage motors separation: 0.5 degrees/s dumped in 30
seconds (maximum attitude error 15 degrees)
To cope with those functions, a maximum torque of 50 300 Nm is needed.
The available torque arms should be:
b1 = 29.4 m,
b2 = 10.4 m
b3 = 4.6 m
b4 = 19.6 m
The contribution from the other stages ACS have already been dimensioned:
Considering 440 N thrust at b1, b2, a torque contribution of 440*(29.4+10.4) = 17500 Nm is
given by those ACS.
Plus 1100 N by b3 = 5000 N which is the contribution of P3,
a total control authority of 22500 N is provided by the already designed ACS
The additional thrust needed in b4 is:
Thrust needed = 50300-22500/19.6 = 1500 N
3.3.5.4 ACS for TMI 2 nd
In this configuration five control points shall be actives: P1, P2, P3, P4 and P5, as shown in
Figure 3-50.