Non Cachable WebSites

I noticed something strange :

    956735986.560 9262 127.0.0.1 TCP_MISS/200 14603 GET
http://www.linux.org/ - DIRECT/www.linux.org text/html (1st request)
    956735997.304 2577 127.0.0.1 TCP_MISS/200 14582 GET
http://www.linux.org/ - DIRECT/www.linux.org text/html (2nd request)
    956736028.223 9045 127.0.0.1 TCP_MISS/200 14578 GET
http://www.linux.org/ - DIRECT/www.linux.org text/html (3rd request)

I do these requests every 2 seconds.
The 1st request ---> TCP_MISS : that's normal.
All the next ones still give a TCP_MISS.

Many WWW sites seem to be not cachable.

Here you can find my squid.conf :
http_port 3128
icp_port 3132
cache_dir /data/cache/squid/cache 100 16 256
cache_access_log /data/cache/squid/logs/access.log
cache_log /data/cache/squid/logs/cache.log
cache_store_log /data/cache/squid/logs/store.log
cache_effective_user nobody
cache_effective_group nogroup
#cache_peer localhost parent 8080 4130

Is there a way to prevent squid to get the document DIRECT from the
origin server ?

We push Web Content over satellite links.
We would like to push whatever Web Site, not only "cachable" WebSites.

Any idea ??

Best Regards,