Speaker
Ms
Elena Vellutini
(Aizoon)
Description
ICATT 2016, 6th International Conference on Astrodynamics Tools and Techniques, 14 - 17 March 2016, ESOC, Germany
Innovative Strategy for Z9 Reentry
Gregor Martens*, Elena Vellutini**, Irene Cruciani*
*ELV
Corso Garibaldi 22, 00034 Colleferro (Italy)
**Aizoon
Viale Città d’Europa 681, 00144, Roma (Italy)
Abstract
Large Footprint of Zefiro 9, the 3rd stage of VEGA launcher spanning even more than 2000 km in equatorial missions, is one of the major system drawbacks constraining both performances and missionization process.
This paper proposes a new strategy for the reentry of Zefiro 9 third stage of the VEGA launch vehicle, consisting of employment of retro-rockets coupled with closed loop guidance, which permits to improve the performance of the launcher and to reduce Z9 footprint.
Z9 is one of the specific characteristics of VEGA: it works at high velocities and high altitude. Being a solid rocket motor it cannot be simply cut off and the impulse delivered depends on the propulsion scattering, not known a priori. This uncertainty produces a big variation in the Z9 impact point, function of the propulsive performance of the SRM.
Current solution for the Z9 reentry foresees the employment of Neutral Axis Maneuver by orienting the thrust along the (neutral axis) predefined direction in order to minimize the impact point variation when an impulse is delivered along. NAM is performed in open loop guidance several seconds before Z9 cut off which is not predictable with precision, hence a certain percentage of its propulsion capability is lost in the maneuver.
The new reentry logic permits to exploit the whole Z9 energetic capacity by not performing the neutral axis maneuver. Footprint extension is moreover drastically reduced by employment of retro rockets: small solid rocket booster with a fixed impulse of velocity. After Z9 exhaustion a slew manoeuver points the launch vehicle to the target attitude computed on-board and retro rockets are activated immediately after separation.
The reentry logic is deeply analyzed and the adopted optimal reentry strategy is formulated. The improvements are evaluated in terms of Z9 footprint extension. Obtained results are compared with respect to the current reentry strategy. Possible error sources (i.e. navigation, guidance and control errors) are critically evaluated and their impact on the results is highlighted.
| Applicant type | Co-author |
|---|
Primary author
Mr
Gregor Martens
(ELV s.p.a)
Co-authors
Ms
Elena Vellutini
(Aizoon)
Mrs
Irene Cruciani
(ELV s.p.a)
