function expand(item){
document.getElementById(item).style.visibility = "visible";
}

function contract(item){
document.getElementById(item).style.visibility = "hidden";
}

function showImagery(){
expand('imagery');
contract('research');
contract('satellites');
contract('contact');
}

function showResearch(){
hideImagery();
expand('research');
contract('satellites');
contract('contact');
}

function showSatellites(){
hideImagery();
contract('research');
expand('satellites');
contract('contact');
}

function showContact(){
hideImagery();
contract('research');
contract('satellites');
expand('contact');
}

function clearAll(){
hideImagery();
contract('research');
contract('satellites');
contract('contact');
}

function showSurveillance(){
contract('ocean');
contract('atmosphere');
expand('surveillance');
}

function showOcean(){
expand('ocean');
contract('atmosphere');
contract('surveillance');
}

function showAtmosphere(){
contract('ocean');
expand('atmosphere');
contract('surveillance');
}

function hideImagery(){
contract('imagery');
contract('ocean');
contract('atmosphere');
contract('surveillance');
}