SPICE kernel file contents are summarized below. S- Spacecraft ephemeris, given as a function of time. The P kernel also logically includes certain physical, dynamical and cartographic constants for target bodies, such as size and shape specifications, and orientation of the spin axis and prime meridian.
Chronic muscle strains are the result of repetitive movement. This can be due to: 1  sports like rowing, tennis, golf, or baseball. 2  holding your back or neck in an awkward position for long periods of time, such as when you work at a desk.ou can decrease your chances of straining a muscle if you take some basic precautions. 1  Try not to sit in one position for too long. 2  Take frequent breaks to move and change position. 3  Use a chair that provides good support for your lower back or use a pillow for support. 4  Try to keep your knees level with your hips.
Back pain can come on suddenly and last less than six weeks (acute), which may be caused by a fall or heavy lifting. Back pain that lasts more than three months (chronic) is less common than acute pain. Back pain often develops without a specific cause that your doctor can identify with a test or imaging study. Conditions commonly linked to back pain include: Muscle or ligament strain. Repeated heavy lifting or a sudden awkward movement may strain back muscles and spinal ligaments. If you're in poor physical condition, constant strain on your back may cause painful muscle spasms.