Long Islanders are joining the rest of the nation Monday in marking the 40th anniversary of when astronauts landed and walked on the moon.Al Contessa, Ernest Finamore, and John Rockensies were among the Grumman employees who helped build a ship for the mission. The ship was called the Lunar Excursion Module, or the LM.The men now work at the Cradle of Aviation Museum in Garden City, where two of the modules are now on display.