ALBERT

Description: The objectives of this program are to 1) Assess viability of using lithium-ion technology for future NASA applications, with emphasis upon Mars landers and rovers which will operate on the planetary surface; 2) Support the JPL 2003 Mars Exploration Rover program to assist in the delivery and testing of a 8 AHr Lithium-Ion battery (Lithion/Yardney) which will power the rover; 3) Demonstrate applicability of using lithium-ion technologyfor future Mars applications: Mars 09 Science Laboratory (Smart Lander) and Future Mars Surface Operations (General). Mission simulation testing was carried out for cells and batteries on the Mars Surveyor 2001 Lander and the 2003 Mars Exploration Rover.

Description: In early 2004, JPL successfully landed two Rovers, named Spirit and Opportunity, on the surface of Mars after traveling 〉 300 million miles over a 6-7 month period. In order to operate for extended duration on the surface of Mars, both Rovers are equipped with rechargeable Lithium-ion batteries, which were designed to aid in the launch, correct anomalies during cruise, and support surface operations in conjunction with a triple-junction deployable solar arrays. The requirements of the Lithium-ion battery include the ability to provide power at least 90 sols on the surface of Mars, operate over a wide temperature range (-20(deg)C to +4O(deg)C), withstand long storage periods (e.g., cruise period), operate in an inverted position, and support high currents (e.g., firing pyro events). In order to determine the viability of meeting these requirements, ground testing was performed on a Rover Battery Assembly Unit (RBAU), consisting of two 8-cell 8 Ah lithium-ion batteries connected in parallel. The RBAU upon which the performance testing was performed is nearly identical to the batteries incorporated into the two Rovers currently on Mars. The testing performed includes, (a) performing initial characterization tests (discharge capacity at different temperatures), (b) simulating the launch conditions, (c) simulating the cruise phase conditions (including trajectory corrections), (d) simulating the entry, decent, and landing pulse load profile (if required to support the pyros) (e) simulating the Mars surface operation mission simulation conditions, as well as, (f) assessing performance capacity loss and impedance characteristics as a function of temperature and life. As will be discussed, the lithium-ion batteries (fabricated by LithiodYardney, Inc.) were demonstrated to far exceed the requirements defined by the mission, and are projected to support an extended mission (〉 2 years) with margin to spare.

Description: n early 2004 JPL successfully landed two Rovers, named Spirit and Opportunity, on the surface of Mars after traveling 〉300 million miles over a 6-7 month period. In order to operate for extended duration on the surface of Mars, both Rovers are equipped with rechargeable Lithium-ion batteries, which were designed to aid in the launch, correct anomalies during cruise, and support surface operations in conjunction with a triple-junction deployable solar arrays. The requirements of the Lithium-ion battery include the ability to provide power at least 90 sols on the surface of Mars, operate over a wide temperature range (-20 C to +40 C), withstanding long storage periods (e.g., cruise period), operate in an inverted position, and support high currents (e.g., firing pyro events). In order to determine the viability of Lithium-ion technology to meet these stringent requirements, a comprehensive test program was implemented aimed at demonstrating the performance capability of prototype cells fabricated by Lithion, Inc. (Yardney Technical Products, Inc.). The testing performed includes, determining the (a) room temperature cycle life, (b) pulse capability as a function of temperature, (e) self-discharge and storage characteristics mission profile capability, (f) cycle life under mission simulation conditions, (g) impedance characteristics, (h) impact of cell orientation, and (i) performance in 8-cell engineering batteries. As will be discussed, the Lithium-ion prototype cells and batteries were demonstrated to meet, as well as, exceed the requirements defined by the mission.

Description: NASA's Mars Rovers, Spirit and Opportunity, have been roving on the surface of Mars, capturing impressive images of its terrain and analyzing the drillings from Martian rocks, to answer the ever -puzzling questions of life beyond Earth and origin of our planets. These rovers are being enabled by an advanced rechargeable battery system, lithium-ion, for the first time on a space mission of this scale, for keeping the rover electronics warm, and for supporting nighttime experimentation and communications. These rover Li-ion batteries are characterized by their unique low temperature capability, in addition to the usual advantages associated with Li-ion chemistry in terms of mass, volume and energy efficiency. To enable a rapid insertion of this advanced Li-ion chemistry into flight missions, we have performed several performance assessment studies on several prototype cells over the last few years. These tests mainly focused primarily on the long-term performance characteristics, such as cycling and storage, as described in our companion paper. In addition, various tests have been performed on MER cells and engineering and proto flight batteries; under conditions relevant to these missions. For example, we have examined the performance of the cells in: a) an inverted orientation, as during integration and launch, and b) conditions of low rate discharge, between 3.0-2.5 V to support the mission clock. Likewise, we have determined the impedance of the proto-flight Rover battery assembly unit in detail, with a view to asses whether a current-limiting resistor would be unduly stressed, in the event of a shorting induced by a failed pyro. In this paper we will describe these studies in detail, as well as the performance of Li-ion batteries in Spirit and Opportunity rovers, during cruise and on Mars.

Description: In this paper, we will describe the performance charateristics of the Li-ion rechargeable batteries during launch, cruise phase and on the surface of Mars thus far.

Description: NASA's Mars Rovers, Spirit and Opportunity have been exploring the surface of Mars for the last thirty months, far exceeding the primary mission life of three months, performing astounding geological studies to examine the habitability of Mars. Such an extended mission life may be attributed to impressive performances of several subsystems, including power subsystem components, i.e., solar array and batteries. The novelty and challenge for this mission in terms of energy storage is the use of lithium-ion batteries, for the first time in a major NASA mission, for keeping the rover electronics warm, and supporting nighttime experimentation and communications. The use of Li-ion batteries has considerably enhanced or even enabled these rovers, by providing greater mass and volume allocations for the payload and wider range of operating temperatures for the power subsystem and thus reduced thermal management. After about 800 days of exploration, there is only marginal change in the end-of discharge (EOD) voltages of the batteries or in their capacities, as estimated from in-flight voltage data and corroborated by ground testing of prototype batteries. Enabled by such impressive durability from the Li-ion batteries, both from a cycling and calendar life stand point, these rovers are poised to extend their exploration well beyond 1000 sols, though other components have started showing signs of decay. In this paper, we will update the performance characteristics of these batteries on both Spirit and Opportunity.

Description: Both NASA and the U.S. Army have interest in developing secondary energy storage devices that are capable of meeting the demanding performance requirements of aerospace and man-portable applications. In order to meet these demanding requirements, gel-polymer electrolyte-based lithium-ion cells are being actively considered, due to their promise of providing high specific energy and enhanced safety aspects.

Description: NASA has interest in secondary energy storage batteries that display high specific energy, high energy density, long life characteristics, and perform well over a wide range of temperatures, in order to enable a number of future applications.

Description: No abstract available