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Ariane 4

The basic Ariane 4, also known as the Ariane 40 variant, is a three-stage liquid propellant booster with a 1.9-metric ton payload capacity to a 7 degree inclined GTO or 2.7 metric tons to an 800-km, sun-synchronous orbit. The first stage, (L220) is powered by 4 Viking 5C engines burning nitrogen tetroxide and a combination of UDMH plus hydrazine hydrate called UH25. The second stage (L33) employs the same propellants with a single, higher thrust Viking 4B engine. The third stage (H10 or H10 Plus) burns liquid oxygen and liquid hygrogen through an HM-7b engine (References 1-4).

The Ariane 4 program is managed and launch services are marketed by Arianespace, while the French space agency CNES is responsible for overall design and serves as a general contractor. The primary industrial agent and integration contractor for stages one and three is Aerospatiale. Germany's DASA is the prime contractor for stage 2. Main engines are provided by SEP. In all, more than three dozen European companies provide significant services in the design, manufacture, and operation of the Ariane 4.

The Ariane 40 variant has actually only flown three times to place payloads into low altitude, sun-synchronous orbits (1990, 1991 and 1993). Since the principal mission of Ariane 4 is to insert commercial satellites into GTO, five other booster variants are available depending upon the mass of the payload and whether one or two main satellites are to be carried. The five variants are distinguished by the number and type (liquid propellant or solid propellant) of the small boosters attached to the first stage. The original GTO payload capacity ranged from 2.6 metric tons for two solid boosters (PAP, Propulseur d'Appoint Poudre) to 4.2 metric tons for four liquid boosters (PAL, Propulseur d'Appoint Liquide) (Figure 2.5). The most widely used variant is the most powerful Ariane 44L, and by the end of 1993 all the variants had flown at least once. During the 1990's upgrades (lengthening of the third stage and a new propellant management technique) increased the lifting power of Ariane 4, bringing the Ariane 44L capacity up to 4.7 metric tons (References 5-7). The major contractor for the PAL, which employs the same propellants as the first two stages and a Viking 6 engine, is DASA/ERNO, whereas SNIA/BPD is in charge of the PAP.

To permit the launching of two large, independent spacecraft on a single booster, one satellite is encased in a special housing SYLDA or SPELDA (Systeme de Lancement Double Ariane or Structure Porteuse pour Lancements Double Ariane), while the second satellite is mounted on top of the housing. Both the housing and the upper satellite are then covered by the payload shroud which is jettisoned at an altitude of about 115 km. Once the Ariane thin stage reaches GTO, the upper satellite if released, followed by separation of the top position of the SYLDA or SPELDA and release of the second satellite. Injection into GEO is the responsibility of the individual satellites. For the infrequent LEO missions, a multiple payload platform called ASAP (Ariane Structure for Auxiliary Payloads) can carry up to six small (less than 50 kg) piggy back satellites without interfering with the primary payload.

A total of 15 Ariane launches were conducted during 1993-1994 (the same as the 1991-1992 period) carrying 31 individual spacecraft, only one of which was sponsored by ESA (Section 8). Unfortunately, the flights of missions 63 and 70 (January and December 1994) both failed to reach Earth orbit due to malfunctions in the cryogenic third stage. An accident investigation for flight 63 found the principal cause of failure to be overheating of the LOX turbo pump bearing, which had already been identified as a deficiency and was scheduled for correction by flight 70 (References 8-10). By April, 1994, a redesigned third stage engine was delivered to Aerospatiale, and flight operations resumed in June. However, after six successful Ariane flights in as many months, flight 70 failed to reach Earth orbit when the flow of oxygen to the gas generator was restricted, leading to a significant loss of thrust and eventual burn termination by an on board computer (References 11-14).

One of the side-effects of the two 1994 failures was a streamlining of launch preparation tasks which reduced the launch cycletime from four weeks to only three weeks. The backlog of Ariane missions and high traffic demand are likely to combine for a record number of launches during the 1995-1997 period, barring further mishaps. Ariane 4 is scheduled to be phased out by 1998-1999 after more than 100 missions.



REFERENCES

1. Ariane 4, Arianespace, October 1983.

2. Reaching For The Skies, BR-42, ESA, 1988.

3. Ariane, "Space Special" by MBB Deutsche Aerospace, May 1991.

4. Ariane, Arianespace, May 1990.

5. "50th Ariane the First of a New Batch", Spaceflight, June 1992, p. 184.

6. P. B. de Selding, "Bigot Announces More Modifications for Ariane Launcher", Space News, 18-24 January 1993,p.8.

7. "New Mission Procedure Proposed To Increase Ariane Performance", Aviation Week and Technology , 29 June 1992, p. 47.

8. P. B. de Selding, "Designers Had Flagged Suspect Ariane Component", Space News, 28 February -6 March 1994, pp. 4, 21.

9. "Arianespace Aware of Bearing Problems," Space, May-June 1994, p. 38.

10. C. Covault, "Launch Failure Grounds Ariane", Aviation Week and Space Technology, 31 January 1994, pp. 27-28.

11. C. Lardier, "Coup d'Arret Apres l'Echec d'Ariane (V70)", Air & Cosmos , 9 December 1994, pp. 38-39.

12. C. Lardier, "Prochain Vol d'Ariane Fin Fevrier", Air & Cosmos , 6 January 1995, p. 62.

13. C. Covault, "Ariane Mission Review Cites Contamination Control", Aviation Week and Space Technology, 2 January 1995, pp. 58-59.

14. C. Covault, "Ariane Flights Halted to Examine Third Stage", Aviation Week and Space Technology, December 1994, pp. 25-26.

Sources and Resources


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