ExoMars Transfer and Approach Phase Navigation
- Paper number
IAC-06-C1.8.09
- Author
Mr. Jose Manuel Sanchez Perez, GMV S.A., Spain
- Coauthor
Mr. Michael Khan, Germany
- Year
2006
- Abstract
The ESA ExoMars mission plans to deliver a spacecraft containing a descent module that carries a high-mobility Rover and a fixed station to perform in-situ biological, geophysical and environmental studies of the Mars surface. The current mission baseline foresees a single Soyuz-Fregat 2.1b launch in 2011 from the European space centre in Kourou of a carrier spacecraft that will deploy the descent module from the hyperbolic approach.
The mission design has attempted to reduce the risk to the atmospheric entry or the surface operations associated with large regional or global Mars dust storms, which are more prevalent and likely to occur during a 6-month period straddling the Mars perihelion. Instead of the usual direct transfer to Mars, for the first time ExoMars will use a delayed transfer trajectory of about 2-years giving slightly less than 1.5 heliocentric revolutions. This strategy, while delaying Mars arrival to after the assumed global dust storm period, will also present some challenges for the navigation of the final approach phase and targeting to the entry conditions due to the high Earth range of 2.5 AU and the occurrence of a superior conjunction between the spacecraft and the Earth about 45 days before the arrival.
This paper presents a summary of the mission design focusing on the results of the preliminary analysis of the approach phase navigation and the targeting to the descent module entry conditions. As part of the interplanetary navigation strategy, a dedicated orbit determination campaign starting just after the communication black-out produced by the conjunction is foreseen to prepare up to three trim correction manoeuvres targeting the descent module entry conditions. Of great importance for the descent module design is the accuracy achievable on the flight path angle at the entry to the Mars atmosphere (entry corridor). Analyses have been conducted to assess the influence on the targeting accuracy of ΔDOR (Delta Differenced One-way Range) measurements added to the Doppler and range data. In order to reduce the delivery errors, the targeting strategy has to include a last correction manoeuvre as close as possible to the Mars arrival while ensuring enough time to perform the descent module deployment and the retargeting of the carrier spacecraft.
- Abstract document
- Manuscript document
IAC-06-C1.8.09.pdf (🔒 authorized access only).
To get the manuscript, please contact IAF Secretariat.