NASA is planning a return to the moon in the next decade with extended human presence on the lunar surface for both scientific and commercial objectives. Significant astronaut activity will be conducted in a spacesuit or extravehicular activity (EVA) suit. The suit becomes the astronauts personal habitat-supplying oxygen, removing carbon dioxide and maintaining appropriate temperature. During lunar surface exploration, the astronauts must have continuous real-time feedback to assure that all consumables (oxygen, cooling water, power) last until they can return safely to their quarters. The consumption rate of these resources depends upon the metabolic rate of the astronaut during EVA tasks and the suits ability to manage thermal loads.

This project will develop novel algorithms for our existing near infrared spectroscopy (NIRS) platform for real-time assessment of metabolic rate (measured as the rate of oxygen consumption, VO₂) and muscle temperature. This capability is intended to be incorporated into biosensors which will be part of a smart system to advise astronauts about their usage of consumables during lunar surface activities.

Specific Aims

1. Develop and validate algorithms to accurately calculate VO₂ from NIR spectra collected from muscle;
2. Develop and validate algorithms to simultaneously calculate muscle temperature;
3. Support incorporation of the sensor algorithms into the EVA suit testing program, where practical.

With synergistic funds from the U.S. Army Medical Research Command and an additional small grant from NSBRI, we have designed and demonstrated a completely solid-state (non fiber based) sensor. This sensor runs off a small battery pack and a handheld computer. A sophisticated user interface performs automated system set-up and on-the-fly error checking to optimize data quality in the face of changing blood flow. After laboratory evaluation in the Johnson Space Center Cardiovascular Lab, the system will be available for in-suit testing by the EVA Physiology Project.

This project has produced a prototype wearable sensor that terrestrial doctors and their patients can use to track and optimize exercise in the management of health and fitness, as well as during related applications in the care of critically ill patients.

Earth-based Applications of Research Project
This work will have direct Earth-based application. The fitness and exercise applications we are developing can be used to assist in the training and evaluation of elite and recreational athletes. This direct application, of interest to NASA for assessing fitness in space, may be useful to assess success of physical therapy in rehabilitating patients with muscle injury or atrophy.

The sensor, which also is of tremendous interest to the Army, will have application in emergency response vehicles, emergency rooms and hospitals. Pre-hospital applications include assessing the severity of shock and triaging multiple casualties, as well as providing a sensor for a smart medical system to guide resuscitation from hemorrhage. In the Intensive Care Unit, we expect that this monitor will find application in helping provide early identification of patients with hemodynamic instability before they go into shock.

The miniaturization of the sensor and monitor, required for extravehicular activity (EVA) suit placement, will result in a highly portable system for emergency medical use. If small and inexpensive enough, it could be used worldwide for screening of anemia associated with malnutrition.

Project Description
NASA Task Book Entry