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Alternative descent/landing technologies (ADLT)
For any planetary exploration mission to Mars, one of the most challenging phases is landing on the planetary surface. Indeed many past missions to the Red Planet have been unsuccessful due to a failure during the final moments before landing.
Successful solutions to the problem of landing to date have included soft-propulsive landing (as for Viking), and harder, bouncing airbag assisted landing (as for Pathfinder and the MERs).
While the propulsive system is more suitable for larger payloads, airbag based systems have been shown to be more mass efficient for smaller scale missions. However alternatives to the conventional bouncing bag concept do exist and should be investigated since they may offer even further mass savings for certain sizes of payloads.
Conventional airbag concepts to date have consisted of a ‘billiard-ball’ type of arrangement with a payload capsule entirely surrounded by airbags. When released from the descent parachute, the payload and airbags bounce many times on the surface before coming to rest. This setup also requires the payload to have some form of self righting mechanism.
The alternative concept investigated within this activity consists of a hexagonal platform surrounded by airbags containing vent valves. On landing, sensors send a signal to open the vents which causes a rapid but predictable deflation. In this concept there should be no bouncing and the payload should come to rest in a predictable, upright orientation.
The ADLT activity itself models the entire descent and landing phase, from the end of the entry phase, through the deployment of parachutes, the activation of propulsive velocity control systems and finally the landing with a vented airbag system. This theoretical approach will identify many of the critical operational and technological factors involved, and also give an indication of where to focus future activity, including hardware development and testing.
In addition to this theoretical consideration of the descent and landing sequence, the activity will also develop and test a breadboard of the vented airbag concept to prove the feasibility of the concept. This testing will involve dropping a representative payload equipped with a vented airbag system, including sensors, with actuators etc. The results of this testing will provide data to validate some of the theoretical modelling work, and give an insight into how to further develop this technology. A first series of successful tests was performed in 2005. Further testing is currently ongoing.
With entry, descent and landing being one of the most critical capabilities for all planetary surface exploration missions, not only for ExoMars, it is important to investigate different possible concepts and develop them where they have proven to be advantageous to the mission. With a successful demonstration of the vented airbag concept, this activity may be the beginning of such a process.
| Start |
Expected or actual duration | Status | Prime contractor |
|---|---|---|---|
| March '04 | 26 months | Ongoing (CCN) | Vorticity |
Executive Summary