On 9 April 1999 the second (and last) Titan IVB from Pad 41 put an IUS with a DSP satellite into low parking orbit.44^5 The Orbus 21 first stage of the IUS accomplished the burn for geosynchronous transfer orbit, but at apogee the Orbus 6E second stage shut down prematurely while attempting to circularise. Since its debut in 1982, the IUS had suffered only two operational failures and was considered reliable.46 A NASA representative joined the Air Force investigation because an IUS was to deploy the Chandra X-ray Observatory from a Shuttle in July 1999 (a mission that had later to be postponed).47 The nozzle of the second-stage motor of an IUS forms three nested sections while stacked. After the first stage has been shed, the two extendable sections of the nozzle are 'cranked' into position. In considering the possibility that the nozzle had failed to deploy, the investigation found that the first stage had not separated properly. The thermal wrap and tape that were applied to a harness and connector had inhibited the disconnection of a plug linking the two stages, with the result that they remained attached at one point, which formed a 'hinge'.48 The dangling first stage damaged the nozzle of the second stage, and when
that motor ignited it set the vehicle tumbling in a way that the attitude control system could not counter.49 Ironically, the technicians had followed the procedure that had been in force since the introduction of the IUS, which in retrospect was flawed by its failure to take account of the potential for disabling the internal mechanism of the separation connector. The 2.5-tonne DSP did not have the propellant to undertake its own circularisation burn. Despite the loss, the Air Force insisted that its missile-launch warning system still had "complete world-wide coverage".50
Twenty-one days later, on 30 April, the Centaur of a vehicle launched from Pad 40 stranded a Milstar satellite!51^2 The investigation found a software error in the guidance system.5W5 The 'constant' for the roll rate had been entered with the decimal point one place to the left, making it one-tenth of the value. In attempting to cancel an anomalous roll during its first burn, the Centaur had consumed 85 per cent of its hydrazine attitude control propellant, and thereafter ran dry when trying to do so during a later manoeuvre, with the result that it released its payload in an orbit with an apogee that fell far short of geosynchronous altitude. Of course, the great mystery was that the software verification process at Lockheed Martin Astronautics had missed this slip. In fact, data that would have shown something amiss in a test a week prior to launch had not been monitored, and anomalous indications in the final hours of the countdown were misinterpreted.56 At $1.23 billion ($880 million for the satellite and $433 million for the launch vehicle) this was the most costly satellite loss to date for the Department of Defense.57
Although the Titan IVB had suffered two upper stage failures in succession - one an IUS and the other a Centaur - it was possible to proceed with the next mission as it did not require an upper stage. At T+12 minutes after lifing off from Vandenberg on 22 May 1999, the National Reconnaissance Office payload was released to make its own way to its operating station.58,59,6°
The recent problems involving the Titan IV were investigated by an Independent Assessment Team on Mission Success chaired by Thomas Young, former president and chief operating officer of Martin Marietta. This highlighted a number of quality control issues derived from the shedding by Lockheed Martin of experienced personnel and an overemphasis on cost-cutting - in short, the improper application of the 'faster-better-cheaper' mantra.61,62,6S This report prompted major management and quality control changes.
The hiatus ended on 8 May 2000, when a Titan IVB was launched from Pad 40 with an IUS that deployed a DSP satellite to replace the one that had been lost.64,65,66
The Proton was developed in the early 1960s by Vladimir Chelomei, who was one of Sergei Korolev's rivals. The first stage of the Proton had an oxidiser tank in the centre of six narrower fuel tanks, and an engine at the base of each of the peripheral assemblies. Unlike Korolev, Chelomei used storable hydrazine and nitrogen
tetroxide as propellants. The two-stage version tested in 1965 carried a scientific payload named Proton, which gave the vehicle its popular moniker. With a third stage, it could insert '20 tonnes' into low orbit, and was used in this form to launch heavy satellites and space station modules. With a fourth stage derived from the fifth stage of Korolev's giant N-1 moonrocket, known as the Block-D,67 it could deliver satellites into geostationary orbit and dispatch heavy probes to the Moon and into deep space.
The Proton initially had a high proportion of failures, with 16 out of 25 launches in the first five years suffering a mishap, but went on to become a reliable vehicle with just 10 further losses by the time of the 100th launch in 1982.68 After the loss of a Raduga satellite on 24 December 1982 there was a long run of successes until an Almaz radar-imaging satellite was lost on 29 December 198 6.69 A commmunications satellite was stranded in geosynchronous transfer orbit on the next launch, on 30 January 1987, when the Block-D failed to make the circularisation burn.70 A Raduga satellite was inserted into geostationary orbit on 19 March 1987. It was initially denied that the launch on 24 April 1987 had been a failure,71 but it was obvious that it had been carrying three satellites for the GLONASS system, the Soviet version of GPS. This system was at an altitude of 19,100 kilometres, with satellites in three orbital planes inclined at 65 degrees, with a 45-degree spacing between the satellites in a plane and the planes separated by 120 degrees in longitude.72 In this case, the Block-D's engine had shut down prematurely, falling 1,350 kilometres short of the requisite apogee. A restart command from the ground was ineffective, and it became apparent that the engine was damaged when the circularisation burn failed to occur.
The timer, oblivious to the situation, then proceeded to eject the satellites.7^74 The investigation concluded that the failures of 30 January and 24 April were due to a system upgrade, and that there was no reason to ground the older Block-D. Flights resumed on 11 May 1987 with a Block-D successfully inserting a Gorizont communications satellite into geostationary orbit. A Proton suffered a third-stage failure on 18 January 1988, a Block-D failed on 17 February 1988, and on 9 August 1990 a vehicle was unfortunately lost as a result of a worker leaving a rag in the second stage's propulsion system.75,76
Nevertheless, as the Proton was a heavy-lifter with a good record on 200 launches, in early 1992 a Lockheed delegation made an impromptu visit to Khrunichev to propose a joint venture, and one year later, with approval of both the US and Russian governments, Lockheed Khrunichev Energiya Incorporated (LKEI) was created to market the Proton. Although a Gorizont satellite was lost on 27 May 1993 when an engine in the second stage exploded due to a fuel contaminant,77,78,79 several months later LKEI signed up its first customer.80
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