Ulysses, a joint ESA/NASA mission launched in October 1990, will be the first to explore the high latitude heliosphere. Launch will be from the Shuttle and a Jupiter gravity assist will be used to send the spacecraft first over the southern solar pole approximately three and one half years after launch and then over the northern solar pole one year later. Instruments will be carried to study the solar wind, the heliospheric magnetic field, energetic solar particles, galactic cosmic rays, solar X- rays, cosmic gamma rays cosmic dust and interstellar neutral helium. The radio signals used to track and transmit spacecraft data will be used also to sound the corona and to search for gravitational waves.

Plans for astrophysics science operations during the decade of the nineties are described from the point of view of a scientist who wishes to make a space-borne astronomical observation or to use archival astronomical data. In the process of preparing a proposal, making an observation, and carrying out data processing, analysis, and dissemination of results, the scientist will be able to use a variety of services and infrastructure, including the “Astrophysics Data System”. The current status and plans for these science operations services are described.

United States policy for national space launch capability provides for a balanced mix of launches, utilizing the Space Shuttle and Expendable Launch Vehicles (ELVs). It also directs government agencies to encourage and support the development of a domestic commercial expendable launch vehicle industry. This is to be accomplished by contracting for necessary ELV launch services directly from the private sector and by facilitating access by commercial launch firms to national launch and launch-related property and services they request to support these commercial operations.

The current mixed fleet includes the Space Shuttle and four expendable launch vehicles - Titan, Atlas, Delta and Scout. New small class launch vehicles, including Pegasus, are in development. In addition, studies are underway to assure that the United States has cost-effective, reliable access to space, heavy-lift launch capability, and a new manned spacecraft after the current Space Shuttle reaches the end of its operational life. This paper will highlight the current capabilities of the mixed fleet and summarize the plans for new or modified United States launch vehicles through the first decade of the next century.

The overall development of ESA’s Space Transportation Programme can be perceived in two major phases. The first phase finished with the transfer of the ARIANE 1-4 launch systems to Arianespace for utilisation and commercialization. The second phase was started after the success of the ARIANE launcher programme had created a sound basis for Europe’s space industry in the evolving commercial space transportation market. This has lead to the definition of a second phase of the launcher development program which is expected to fulfil the needs for transport into space for many years to come. The wide objectives of the program makes it not only suitable for commercial applications but can also be expected to cover the launching needs for future Space Astrophysics missions.

Market studies of the future commercial space transportation needs show growing satellite masses and an increased worldwide competition. Europe therefore needs a powerful launcher with improved cost-effectiveness and improved reliability for geostationary missions. On the other hand the discussion about the optimum launcher, spacecraft size and orbits for Astronomy missions, as well as for Space Science missions in general, is still a matter under debate, as explained by Dyson elsewhere in these Proceedings. The experience obtained with IUE and EXOSAT-Observatory satellites which, due to their general user nature, do not have a rigidly preplanned observing program - seem to suggest that, at least for operational motives, high orbits appear preferable for such satellites. This is especially true as compared to the operational and planning difficulties foreseen with the recently launched Hubble Space Telescope, which is in low earth orbit (LEO). Of course, for firmly pre-scheduled observatories with a predetermined Science program, such as COBE and HIPPARCOS, this choice may not be obvious.

The Institute of Space and Astronautical Science (ISAS) has developed a series of launch vehicles for delivering modest scale scientific satellites into space. This capability is unique for an inter-university research institute. The present ISAS launch vehicle, M-3S II, carries a 770 kg payload into a low earth orbit (LEO). A new program for the development of a more capable vehicle, M-V, started recently, which will have a LEO capability three times that of M-3S II. The enhanced launch capability will further expand the scope of the ISAS missions to include planetary explorations.

The invited speaker from Moscow for this talk was unable to attend the Colloquium due to circumstances beyond his control. The following data concerning the U.S.S.R. Launch Systems have been taken from information published in Soviet journals.

None of us thought, when this colloquium was scheduled, that the timing would enable it to become a celebration as well. The launch, after years of postponements, of the Hubble Space Telescope, has cast a galactic glow over the proceedings here this week. But at the same time, the frustrating delays caused by the collapse in 1986 and very slow regeneration of the U.S. space launch capabilities since then make this discussion of near-earth access very pointed.

As we know, the sheer momentum of the U.S. Space Shuttle Program has dominated our perceptions of space launch for a decade and a half. It reached its peak in the early 1980s when our national policy placed nearly total reliance on the Shuttle as our means of access to space. It was a policy doomed to fail, for obvious and not-so-obvious reasons.

Among several potential future deep space propulsion systems, the two which are closest to realization are selected for closer consideration: solar-electric, and nuclear-electric propulsion. In particular, the paper describes a manned Mars mission using a particle bed reactor and Brayton cycle converter as power source. Technical details of the design and the mission profile of a 4-astronaut expedition to Mars, and a proposed course of action for project implementation are presented.

The Moon offers for astronomy a truly impressive array of advantages, many of which are briefly reviewed in this paper. These advantages include especially the vast inertial platform and the expected availability of human and robotic “hands-on” installation, maintenance, and modification. The Earth-orbiting Great Observatories will advance our knowledge to a new plateau, but some of the most fundamental observational questions which we are already asking will require lunar-based instruments, including very large filled-aperture telescopes, interferometers with baselines of tens and ultimately hundreds of kilometers, and the utilization of the radio-quiet backside. It is already time to begin planning the first such installations.

One criterium for the best orbit (or site) for an observatory has to be “that which is both scientifically and cost-effective”. Perhaps the worst orbits are those offered by “infrastructures”, which were not designed with astronomy as their primary driver, yet have to be used “because they are there”. The ESA astronomy programme currently tends to favour highly eccentric or geostationary orbits (e.g. COS-B, IUE, EXOSAT, HIPPARCOS, ISO), as these appear to satisfy the above criterium. However, depending on the scientific mission to be accomplished and the availability of funds, other orbits are not ruled out priori.

The diagram (Fig. 1) qualitatively exhibits how several important observations will have to be undertaken. Here, I would like to, at least, raise the question or discuss the problem referring to “Man in Space”.

My question is as follows: How the man in space, like the Space Shuttle, and the robotics, like Voyager, precede the man in space “and/or” the robotics in the 21st century? I think, the answer is not obvious and we have to be cautious to make decisions. Once we make the decision, we may not be able to go backwards because the investments will be enormous and the impact to all humans will be very deep.

The moon offers mixed blessings as a site for astronomical observatories, and some of these are presented in Tables I and II (see the paper by Smith for a more complete discussion). The advantages are so strong that they make the moon a unique site for certain kinds of observatories, particularly those which feature very large telescopes or interferometric arrays of large dimensions, and those that require a presence beyond the screening effect of the earth’s magnetic field. More than one hundred scientists gathered at Annapolis, Maryland for a Workshop on Astrophysics from the Moon (Feb. 5-7, 1990), and discussed these questions in considerable detail (Mumma and Smith 1990). The objective was to examine the astrophysical frontiers of the 21st century, and to identify those which require the presence of astrophysical observatories on the moon for their successful address. The scope of the Workshop was defined to include all areas of space astronomy. It was assumed that the base program of space astronomy will have been completed prior to the emplacement of lunar-based observatories, thus that the four Great Observatories, the Solar and Heliospheric Observatory, the Orbiting Solar Laboratory, the Coronagraphic Imaging and Astrometric Telescope Facility, and the Earth-Orbital Planetary Telescope will all have been accomplished. The Workshop participants tried to look beyond the scientific objectives to be addressed with those Earth-orbiting facilities to the next generation of scientific frontiers, which are associated with the very small, the very distant, and the very faint. This paper summarizes some of the ideas presented there, but these are presented in much greater detail in the published Proceedings (Mumma and Smith 1990).

The Sun-Earth libration points, L1 and L2, are located 1.5 million kilometers from the Earth towards and away from the Sun. Halo orbits about these points have significant advantages for space observatories in terms of viewing geometry, thermal and radiation environment, and delta-V expediture.

Big space-instruments are essential for observing fine details of selected objects. Small space-instruments are essential for scanning large areas of sky, for discovering and cataloguing new objects, and for monitoring variable or transient sources of radiation. If astronomy is to flourish, both types of instrument must be provided. The problem is not to choose between big and small. The problem is to find the optimum mixture of big and small. Various examples from past history and from future plans illustrate the importance of maintaining a variety of different types of instrument.

Observational technology in astronomy moves ahead. We can see a thousand times fainter and ten to a hundred times more detail than 40 years ago. But does our application to research match the engineering progress? Most of us make the easy assumption that theory is right at the cutting edge, waiting to gobble up each new fact into an even deeper, more detailed insight into the universe. But humans frequently misunderstand the real problems and misapply technology - making everything worse for agonizingly long times.

Is it possible that extragalactic astronomy has serious misconceptions? The key point to appreciate is that its whole structure rests on the belief that we know the distances to objects in the universe. The simple shift to the red of the spectrum of any observed object is assumed to measure its distance. But for 25 years evidence has been increasing that drastically incorrect distances can result. Unfortunately, not only quasar distances but the distances to the vast majority of galaxies also depend on redshifts.

The era of occultation astronomy, studying dark objects by observing occultations of bright ones, has begun. The paper of Duncan, Quinn and Tremarne, “The Origin of Short-Period Comets”, Astrophys. J. Letters, 328, 69-73 (1988), greatly improved the prospects for occultation astronomy by demonstrating the existence of a second comet reservoir, the Kuiper Belt, much closer to us than the Oort Cloud and concentrated toward the ecliptic plane. Charles Alcock at Livermore (private communication) has begun work on a practical system of small telescopes to observe occultations of stars by comets. I here propose a system similar in concept of Alcock’s but using different hardware. We need to try various systems on a small scale to find out which are most cost-effective. My proposal is based on the Multiple Telescope Robotic Observatory (MTRO) developed by Boyd and Genet at Fairborn Observatory in Arizona. See Russell M. Genet, “Multiple-Telescope Robotic Observatories in Space”, submitted to P.A.S.P. (1990).

The word 'origin' is one of the most widely used in science. Yet it seems to me to be always used either improperly or ineffectively. Ineffective uses have a derivative quality about them. As an example, suppose we ask: What was the 'origin' of the magnetic field of the Sun? The best answer I suppose is that the magnetic field of the Sun was formed by the compression of a magnetic field that was present already in the gases of the molecular cloud in which the Sun and Solar System were formed some 4.5 X 109 years ago. But what then was the 'origin' of the field in the molecular cloud? It was present already in the gases from which our galaxy was formed, one might suggest. A further displacement then takes us to the manner of 'origin' of t he entire universe, so that no ultimate explanation has really been given. The problem has only been displaced along a chain until it passes into a mental fog through which some claim to see clearly but through which others, including myself, do not see at all.

It is with some trepidation that I set down these thoughts. The history of physics and astronomy is littered with pontifications about the future, most of which simply end up embarrassing their authors. There are many projects which can be regarded as very safe bets but these might not be the ones which totally transform the nature of the discipline. The situation is analogous to that in the early 1950s when extragalactic astronomy simply meant optical astronomy since there was no other way of carrying out such studies – few would regard that as an adequate position nowadays. Similarly, it is difficult nowadays to imagine cosmology without the Microwave Background Radiation. Thus, the problem for the prognosticator is to tread the narrow line between science fiction and a simple extrapolation of what we do now with our facilities. It is in the spirit of this meeting to concentrate upon space observatories but I believe that it is instructive to look at the whole of astronomy, both from space and from the ground.

I would like to trace the evolution of the major problems or questions since the 1950’s by showing several diagrams (Fig. 1a-e) based on my own recollections. As for the coordinates of the diagrams, the latitude towards North indicates the magnitude of surprise and that towards the South indicated is the deepening of our knowledge. Of course such a visual approach is incomplete and is full of personal prejudices, and many important subjects and considerations may be missing.

I will not go into detail of the interpretation of the diagram. But from the series of the diagram we may see that unification and diversification of the questions alternate as one of our co-panelists, Freeman Dyson, pointed out in one of his inspiring books.

In the 1970’s to the 1980’s we had good hopes that GUT would develop and in its evidence mono-poles and Proton-decay’s would be discovered and that proposed candidates of the dark matter may also be discovered from fairly reasonable particles to much more exotic particles.

The SPECTRUM - X-GAMMA mission is being developed by the Space Research Institute (IKI), USSR, together with many other countries and is scheduled for launch in 1993 ( Sunyaev,1990; Schnopper,1990). Mission objectives include broad and narrow band imaging spectroscopy over a wide range of energies from the EUV through gamma rays, with an emphasis on studying galactic and extragalactic X-ray sources. The Danish Space Research Institute (DSRI) and IKI will provide two thin-foil X-ray telescopes (SODART), each with an aperture of 60 cm and focal length of 8 m. They are designed to have a half-power width of less than 2 arc minutes and will have collecting areas of 1700, 1200 and 100 cm2 at 1, 8 and 20 keV, respectively. Images and polarization will be recorded by position-sensitive proportional counters. Moderate resolution spectroscopy will be done by the segmented solid state detector SIXA (Silicon X-ray Array), designed and to be constructed by a consortium in Finland, Denmark and USSR. Finland will have the main responsibility in financing and delivering the detector. The Institute of Electromechanics in Moscow will provide its passive cooling system (110 K). The detector will consist of 19 segments (Si(Li)), each with a diameter of about 8 mm. The spectral resolution of 160 eV (at 6 keV), combined with the large collecting area, provide good opportunities for time-resolved iron line spectroscopy ( 6-8 keV). The potential observing program includes stellar coronae, cataclysmic variables and X-ray binaries, accretion discs and coronae of neutron stars and black hole candidates, supernova-remnants, active galactic nuclei, clusters of galaxies and the diffuse cosmic X-ray background. We demonstrate the instrument’s power through some astrophysical simulations.