Hazards to aircraft include debris, nesting birds, and reduced friction levels due to environmental conditions such as ice, snow, or rain. Part of runway maintenance is airfield rubber removal which helps maintain friction levels. The fields must be kept clear of debris using cleaning equipment so that loose material does not become a projectile and enter an engine duct (see foreign object damage). In adverse weather conditions, ice and snow clearing equipment can be used to improve traction on the landing strip. For waiting aircraft, equipment is used to spray special deicing fluids on the wings.
What includes debris and nesting birds?
Hazards to aircraft

The original early 19th-century interior designs, many of which survive, include widespread use of brightly coloured scagliola and blue and pink lapis, on the advice of Sir Charles Long. King Edward VII oversaw a partial redecoration in a Belle Epoque cream and gold colour scheme. Many smaller reception rooms are furnished in the Chinese regency style with furniture and fittings brought from the Royal Pavilion at Brighton and from Carlton House. The palace has 775 rooms, and the garden is the largest private garden in London. The state rooms, used for official and state entertaining, are open to the public each year for most of August and September, and on selected days in winter and spring.
How many rooms does the palace have?
775 rooms

The scientific revolution is a convenient boundary between ancient thought and classical physics. Nicolaus Copernicus revived the heliocentric model of the solar system described by Aristarchus of Samos. This was followed by the first known model of planetary motion given by Johannes Kepler in the early 17th century, which proposed that the planets follow elliptical orbits, with the Sun at one focus of the ellipse. Galileo ("Father of Modern Physics") also made use of experiments to validate physical theories, a key element of the scientific method.
Who made the heliocentric model popular?
Nicolaus Copernicus