Telling that space debris problem is growing annually will not be adequate - pace of increasing number of pieces of space debris is really impressive. From last week number of space trashes rapidly increased for 351 !
The Joint Space Operations Center, American institution which is monitoring number of space debris pieces remaining on the Earth's orbit informed, that spotted and added to their catalog another cloud of space debris. As informs 101spaceflight.com some of these residues are even 50-year old and were part Delta-N rocket launched in 1968. Rest of debris was mainly created by objects from recent years , few are reamings of Kosmos 1275, navigation satellite used by Soviet Army and launched in the 1981.
Appearing of debris generated by 50-year old rocket is not very common. Due the nature of rockets, debris generated by them is rather pretty big - these are mainly stages or parts of payload adapters or fairings. In this case cloud of debris points, that Delta 1968-114B piece which disappeared and generated this particular cloud probably hit in another object or exploded. Appearance of 17 new pieces from Delta 1968-114B object can be also explained by the its explosion. It is possible - exploded could one from fuel tanks of the rocket or its internal battery. It is worth to remind, that residues of the propellant stay inside tanks of Delta (or any other) second stage and they can cause corrosion of tanks and rapid explosion even years after launch. Due the low temperature in space corrosion is not as rapid as on Earth, so in future number of upper stages can be affected with this problem and simply explode as corrosion will move on. Of course 17 new pieces instead one is not big difference, especially if we remind that upper stage is pretty large and weighs 800 kg and is long for 6 m with 1.4 m diameter. If we compare it to satellites, which can generate hundreds of pieces after explosion, problem also not seems to be serious, but there are numbers of upper stages flying around Earth and each can be potentially ticking bomb.
Delta-N two stage expendable launch vehicles were used during 1960s and Launch Complex 17A at the Cape Canaveral Air Force Station and SLC-2 at Vandenberg AFB. This particular rocket was launched from Vandenberg with ESSA-8 weather satellite on the top. Satellite operated on LEO orbit (1470 km x 1421 km) and was finally decommissioned and deactivated in 1976.
Delta rocket on picture is second from right.