The study of martian dust impact on “ExoMars” spacecraft structures unfurling elements after touchdown

DOI: 10.34759/vst-2021-4-192-203

Аuthors

Bernikov A. S., Bogachev V. A.^*, Mikhailov D. N.^**, Petrov Y. A., Sergeev D. V.^***

Lavochkin Research and Production Association, NPO Lavochkin, 24, Leningradskay str., Khimki, Moscow region, 141400, Russia

*e-mail: nio27@laspace.ru
**e-mail: mdn@laspace.ru
***e-mail: sergeevdv@laspace.ru

Abstract

«ExoMars» is an international project intended for studying the Mars surface, obtaining geological samples and detecting traces of possible life existence by delivering a Russian-made descent platform to the surface with a Mars rover onboard.

The structural elements and systems of the «ExoMars» spacecraft should function reliably under the impact of Martian atmosphere factors, which characteristic feature, is constant presence of dust in particular. The presence of the above said operating conditions leads to the necessity of increasing the volume of ground-based experimental tests and functioning check-up of the spacecraft structure unfurling elements

after exposure to dust. Such «ExoMars» spacecraft structural elements include: — The Mars rover ladders;

— Low-directional antenna boom (LDA); — Solar panels (SP).

Dust settling on the structure of mechanisms may lead to clogging the gaps in rotation nodes, abrasive impact on rubbing pairs and, as the result, to the decrease in functional characteristics of mechanisms.

Since the dusty conditions lead to the increase in the energy capacity losses of the springs in the rotation nodes, and the presence of dust on the mechanism structure leads to the increase in its moments of inertia, the angular velocity of the mechanism under dusty conditions should be less, and the unfurling time should increase.

Tests of sand dust impact on the unfurling elements of the «ExoMars» spacecraft structure were performed in a sand-and-dust chamber, representing a device equipped with a closed wind channel and including an internal working volume and a unit for the dust feeding.

To achieve the required dust concentration, a calculated amount of dust was introduced into the chamber, and air was supplied.

The components and elements of the unfurling structures of the «ExoMars» spacecraft intended for laboratory and development tests were subjected to dust exposure tests. They were two ladders for the Mars rover exit, two SAT panels, and an MNA boom. The task of the tests consisted in operability checking of these structures after exposure to dust, as well as to assessing the unfurling time changes prior and after the dust exposure.

The dust exposure tests were conducted in the following order:

— Accelerometer sensors connected to the measuring station were fixed on the structural elements of the unfurling mechanisms, and mechanisms were transferred into the furled position and locked by pyro nodes simulators. Testing ladders opening, the MNA boom and the SB panels was performed manually prior to the dust exposure. The unfurling time was being determined according to the graphs from the sensors;

— The unfurling structures were returned to the folded and locked position. The inner volume of the sand and dust chamber was hermetically sealed. The test objects were being exposed to the dust particles of no more than 50 microns in size for 15 minutes;

— The ladders, the MNA rod, and the SB panels were unfurling after the dust exposure in various spatial positions provided for by the test programs and techniques. The unfurling time for each product was determined according to the obtained graphs from the sensors.

The test results reveal that the dust impact (similar to the Martian dust impact) does not significantly affect the performance of the unfurling structures. The unfurling occurs in the normal mode, the opening time increases herewith by no more than 3% compared to similar tests prior to the dust exposure. Consequently, the energy consumption of the springs of the mechanisms is sufficient for full-scale operation of the spacecraft in Mars conditions.

Keywords:

“ExoMars”, dust exposure, unfurling structural elements

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