June 1983:European space status report

Ariane

It would be too much of a play on words to suggest that Ariane has had its "ups" and “downs." The early days of a launcher will always be difficult, and failures highlighted, but there is full confidence in the long term future of Ariane. ESA remains responsible for the R&D element of the future European Launcher Programme in the sense that the ESA Council decided to undertake a follow-on programme to produce two upgraded versions: Ariane 2 and Ariane 3. The two are of similar design, but Ariane 3 will be fitted with additional boosters. This will give Ariane 2 the capability to place a payload in excess of 2,000 kg into geosynchronous transfer orbit, and Ariane 3 will take more than 2,400 kg - or two payloads of 1,140 kg - in a dual launch. Once the launchers have been proved in flight tests, the responsibility for production models passes to Arianespace and becomes essentially a commercial operation.

Deciding on future generations of launchers requires a crystal ball, in the sense that one needs to assess the requirements of satellite builders and users in the late 1980's and early 1990's. The expectation of the size and scope of geostationary satellites has led ESA to tailor Ariane 4 to allow Europe to offer a highly competitive launch system throughout the 1986-92 period. Ariane 4 will be a versatile launch system capable of putting any payload weighing between 2 and 4.3 tonnes into transfer orbit, by using various combinations of liquid or solid propellant boosters. A demonstration firing is planned for the end of 1985 or early 1986. The cost of placing a kilogramme of payload in orbit is expected to be only 40% of that of Ariane 1. Another milestone in the long term could result from studies of an even higher performance launcher, which would be available from 1990 onwards; this new version should ensure a further cost reduction. To enhance the operational flexibility of the launch facilities and provide redundancy for the present Ariane launch site (ELA-1), it has been decided to construct a second Ariane launch site (ELA-2) in Kourou. By 1985, this will reduce to one month the necessary interval between successive launches of the various uprated versions of Ariane.

Manned European Flight

The arguments for and against European participation in manned flight waxed strong before the decision was made to build Spacelab, and have continued during the development stage. One suspects that they will still be voiced after the first flights this year. The initial success of the Shuttle, and the less publicly acclaimed success of the first Spacelab element - the pallet - to fly, is heartening.

In operation, Spacelab - both the pressurised module and the pallet - will be transported to and from orbit in the cargo bay of the Shuttle Orbiter, and will remain there throughout the flight. Spacelab therefore extends the Shuttle's capability, and the Orbiter/Spacelab combination constitutes a space station which can remain in orbit for about seven days. This "space station" will provide opportunities for experimenters to live and work in space under conditions that are little more exacting than those experienced on Earth. Furthermore, Spacelab can be reconfigured after each flight to satisfy the needs of the next mission. Considerable flexibility in configuration and mission structuring is available to the user.

Only after two or three flights will we have assessed the full implications of Spacelab and its potential uses, especially the extent to which it can be used for the manufacture of prototype commercial products impossible to produce on Earth. These include alloys and composite materials with new properties, crystals of improved characteristics for the electronic components industry, high quality glasses for the optical industry, improved vaccines and biological products.

Apart from improving the existing model to increase time in orbit, experiment capacity and power, Europe is looking ahead to an era when the Shuttle will be used as a means of taking free-flying payloads into space, and retrieving them later. With this in mind, studies are well advanced into various configurations for Eureca: the European Retrievable Carrier. The cry of "Eureka" is attributed to Archimedes when he found a means of determining the purity of gold. Naturally we hope Europe will find gold in its advanced ideas for such space platforms.

Other Projects

I have already mentioned our past successes in the scientific field. Briefly, ESA has five scientific projects in various stages of development:

Exosat will determine the positions and examine the structures of celestial X-ray sources. It will use lunar occupation as well as other observation methods. The satellite is ready and awaits a suitable launch window.

Space Telescope: this 2.4 m telescope will dominate astronomical research for the rest of the century, contributing appreciably to our understanding of the Universe. Europe is providing about 15% of the total cost: the Faint-Object Camera, its associated detector and the solar array. In return we will have 15% of the observing time of the telescope which is due to operate for at least 10 years.

The International Solar-Polar Mission (ISPM) has been dogged by ill-fortune. The original idea to send two satellites out of the ecliptic plane with the help of Jupiter's gravitational field to fly over the Sun's north and south poles had to be abandoned when the NASA spacecraft was a victim of the budgetary cuts. ESA kept faith with the scientific community but the indecision over the development of an interim upper stage, by means of which the satellite will be launched into an Earth-Jupiter transfer orbit from the Shuttle, has delayed the launch still further.

Giotto has captured the imagination of the world; laymen and scientists alike can appreciate that a ”once-only" mission of this nature needs very precise planning and not a little good fortune to succeed. The satellite will be launched in July 1985, and should encounter Halley's Comet in March 1986, one month after perihelion when the comet is at its most active.

Finally, Hipparcos will measure the five main astrometric parameters of distance, position and proper motions of about 100,000 selected stars.

Communications

The advantages of a European Agency being able to do business with other international organisations was well illustrated when INMARSAT undertook to use Marecs satellites in its worldwide system. The use of satellites for maritime telecommunications was expected to demonstrate a number of advantages over the HF/MF radio frequency bands already in use. In particular, telephone and telex connections would be possible on a direct-dial basis to the subscriber, with the high transmission quality associated with international connections. Such services were not available at anything approaching this quality at HF/MF frequencies, and congestion and the operating proce¬ dures imposed by working under difficult conditions were leading to considerable transmission delays. Waiting times with the new system will be reduced from several hours to a question of minutes, if not seconds.

The Marecs satellites, with a capacity of some 40 channels, permit operations with ship terminals with dish antennae of approximately 1 m diameter. Aside from the pure communications capability (fully maintainable during eclipse), a search-and-rescue feature on the satellite can relay messages to shore from vessels in distress using low-power buoys.

Meanwhile we await the launch of ECS-1 by Ariane, the first element in an operational European regional telecommunications system. The ECS series is ESA's second generation of point-to-point communications satellites. The repeaters of these satellites will be able to relay either telephony or television signals. The ECS satellite, which is a development of OTS, is of the one-tonne class and will have a seven-year lifetime. It will provide services over an area similar to that of OTS, but with a combination of Eurobeam and multiple Spotbeam coverage. The greater prime power requirement compared with OTS leads to the use of a larger solar array. The satellite will have a capacity equivalent to 15,000 telephone channels as well as two TV channels and will, like OTS, operate in the 11/14 GHz frequency bands. It will operate with a network of perhaps 20 ground stations, each with an antenna of between 14 and 18 m diameter.

From ECS-2 "multiservices" will be included. These can be defined as all the non-PTT services, and for ECS-2 are geared to the growing demand for high¬ speed, heavy bulk data transmission and programme transfer. Multinational business concerns are interested in such services for file transfers, high-speed facsimile and video service, including video-teleconference facilities. The major customers for telecommunications satellites in Europe, the PTTs created Interim EUTELSAT to act as their "single customer voice", and also to manage the European satellite telecommunications services, being responsible for their exploitation, and for relations with users. Under the terms of a contract concluded between ESA and EUTELSAT, ESA will provide two satellites in orbit for a period of ten years.