$_ = 'de ad be ef #junk';
/^(\w\w)(?: (\w\w))*/;

##</code><code>##

$_ = 'de ad be ef #junk';
/^(\w\w(?: \w\w)*)/;
my @capture = split ' ', $1;

##</code><code>##

$_ = 'de ad be ef #junk';
my @capture = /\G(?:^|\ )(\w\w)/g;

##</code><code>##

$_ = 'de ad be ef #junk';
my @capture;
while(/\G(?:^|\ )(\w\w)/g) {
    push @capture, $1;
}

##</code><code>##

/(?:^|\G\ )(\w\w)/g