Skylark Rocket Research Articles

Sir Robert Wilson CBE. 16 April 1927 — 2 September 2002

Robert Wilson had broad scientific interests that ranged from laboratory and solar plasmas to quasars. In his early career at Harwell he made fundamental studies of the plasma device Zeta, and discovered a group of extreme ultraviolet emission lines that were also present but unidentified in the solar spectrum. Subsequent work at Culham showed that these were due to highly ionized iron. He initiated a programme of observations using stabilized Skylark rockets that led to the discovery of many important emission lines in the solar ultraviolet spectrum and gave new information on the structure of the solar transition region. He was the founder of ultraviolet astronomy in the UK and led the team that provided the S2½68 instrument on the TD–1 satellite. Ultraviolet astronomy became his main interest after his move to University College London. He was the intellectual driving force that eventually led to the outstandingly successful International Ultraviolet Explorer (IUE), which was the first satellite to be easily accessible to the astronomical community. His interests in astronomy were diverse and, using results from both TD–1 and the IUE, he made significant contributions through his studies of the interstellar medium, hot stars, binary X–ray sources and quasars.

Rocket vapor trail releases revisited: Turbulence and the scale of gravity waves: Implications for the imaging Doppler interferometry/incoherent scatter radar controversy

The rate of diffusion of a trimethyl aluminum trail released by a Skylark rocket over Woomera, Australia (31°S, 137°E), in 1969 is interpreted in terms of molecular and turbulent diffusion, and is related to the scale of internal atmospheric gravity wave winds. Implications for disagreement between imaging Doppler interferometry and incoherent scatter radar winds are explored.

Introductory remarks

The main purpose of this two-day meeting was to review recent results in X-ray astronomy in the U. K. and to relate these to their background in current astronomy. However, an important event in 1977 was the launch of the first of the HEAO satellites, HEAO-1, and so we were extremely fortunate in having Dr Friedman of the N. R. L. to describe some of the results obtained by his group with that satellite. It seemed likely that most of the contributions to this meeting would contain very little description of the apparatus used, so I thought that the most useful and, considering the fact that this was the first meeting of the morning, the most agreeable thing I could do would be to describe some of the major experi­mental equipment that has been used. The first facility available for X-ray astronomy in the U. K. was the Skylark rocket, which was used for the early Leicester survey experiments in the Southern Hemisphere, as well as M. S. S. L. experiments on, for example, fluctuations in the diffuse background. The Skylark programme as such has now been terminated, though the last rocket has yet to be fired, but later papers will give details of significant new results obtained in this way.

The galactic centre

While the Uhuru satellite detected an extended or multiple X-ray source located in the direction of the galactic centre, and while transient and burst sources have been found there by Ariel 5 and SAS-3, there has not so far been any detailed description of this important source. By using results from a coded mask telescope flown in 1976 on a Skylark rocket (the first successful application of such a device in astronomy) and from an extended period of observations with Ariel 5, a number of burst and ir­regular variable X-ray sources have now been discovered. In particular, the region within a few degrees of the galactic centre is evidently one of continual but irregular X-ray activity.

The Bakerian Lecture 1978 - Cosmic exploration by X-rays

Bakerian Lectures dealing with astronomical topics have occurred roughly every ten years during this century. They have therefore something of the character of reports on progress and one need read no further back than Hoyle’s ‘Review of recent developments in cosmology’ (Hoyle 1968) and Ryle’s ‘The nature of the cosmic radio sources’ (Ryle 1958) to discover the background against which are to be seen the dramatic changes of the ensuing period. It stretches from the conception of X-ray astronomy through its birth, with the discovery of the first non-solar source (Giacconi et al . 1962), to its maturity with the availability of satellites to provide long exposures. Nor is it any accident that the root κóσμoς is prominent in the titles of recent lectures for while those of Jeans, Eddington, Milne and Blacket were concerned with our Galaxy, the drama is now truly cosmic. Cosmic X-ray astronomy grew out of the study of the Sun and for this reason its founding father is Herbert Friedman. Giacconi describes well the early history of the subject (Giacconi & Gursky 1974) and tells how, in June 1962, having been interested in the idea by Rossi in September 1959, he and his colleagues detected flux coming neither from the Sun nor from the Moon. Friedman had discussed as early as 1956 ‘how his group obtained puzzling results, which might have been due to celestial X-ray fluxes’, and reported this at the I. A. U. meeting in Moscow in 1958. Stimulated by our solar studies with the Skylark rocket, similar thinking was taking place under the auspices of this Society. Mention of this was made at a conference in the United States in June 1961 (Boyd 1962) but a meeting of the Astronomy Working Group of the British National Committee on Space Research (N. C. S. P./34, 1959 a ) had discussed, in May 1959, the possibility, of mounting ‘Directive X-ray counters’ on the proposed U. K. -I satellite. The minute read ‘Current theories suggested that there may be objects in the sky with strong X-ray emission although inconspicuous visually. A search for these is a matter of great interest and importance.’ It is noteworthy that Hoyle, who had discussed Friedman’s speculations with him, was present at the meeting.

Skylark rockets could be made from spare parts say UK geophysicists

Skylark rockets could be made from spare parts say UK geophysicists

Attitude Control of a Skylark Rocket Using Magnetometers and a Moon Sensor

The problems of attitude control of a Skylark rocket are considered on the specific occasion of a night flight during which, of course, the sun was not available as a pointing vector. Pointing was achieved using magnetometers, while roll control was obtained using a suitably placed moon sensor. The logical sequence, as well as the electronic solution, that insured the acquisition of the correct payload orientation is presented.

Rocket measurements of election concentration in the lower ionosphere at two European locations

Measurements of electron concentrations in the lower ionosphere are reported for 16 Petrel rocket flights from South Uist, Scotland, and for 3 Skylark rocket flights from Sardinia. Variations of the electron concentration with season, latitude, degree of ionospheric absorption in winter, degree of auroral activity at night, and with solar zenith angle are examined. Possible causes of the observed behaviour are discussed and its relationship to the morphology of the Winter Anomaly in ionospheric absorption is demonstrated. Data relating to electron collision frequencies are also presented.

The Crab Nebula - High energy X-ray observation of a lunar occultation

A lunar occultation of the Crab Nebula was observed at X-ray energies above 15 keV by a scintillation counter on a Skylark rocket launched from Spain on 1974 October 7. The angular extent of the region of emission of 75 percent of the total flux between 15 and 150 keV (average photon energy 39 keV) along psoition angle 263degree is found to be 110''+25''. The offset of the centroid of the extended source is such that its projection to the west of NP 0532 is 8''plus-or-minus6''. The variation of size with energy, as found from this and other measurements, sets constraints on models for energy transfer along magnetic field lines in the Crab. (AIP)

A Discussion on astronomy in the ultraviolet - Skylark rocket observations of ultraviolet spectra of γ 2 Velorum and ζ Puppis

A star-stabilized Skylark rocket was launched from Woomera in June 1973 to record ultraviolet spectra of the bright stars y 2 Velorum and £ Puppis. The instrumentation consisted of three Wadsworth-mounted objective grating spectrographs with a combined wavelength range 90-230 nm. Stellar spectra were recorded on Kodak 101-01 photographic film, the in-flight spectral resolution being approximately 30 pm. Two exposures were obtained on each of the target stars. The y 2 Vel spectrum observations extend from 92 to 230 nm and the £ Pup spectrum from 100 to 230 nm. Analysis of the spectra provides information about the composition and properties of the interstellar gas in the line of sight. The observations also provide useful data on the stellar atmospheres. P Cygni line profiles are observed in the spectra of both stars indicating that high velocity material is being ejected.

Classification of New Spectral Lines of Fe XVII Observed in Solar Active Regions

SummaryThis summary reports new emission lines of Fe XVII observed in two coronal active regions (McMath regions 12624, 12628). The lines were recorded by a Bragg plane crystal spectrometer collimated to 3′ FWHM, with a gypsum crystal scanning the wavelength range 8–14 Å. This spectrometer, part of a three spectrometer package previously used by Parkinson (1972, 1973), was mounted aboard a Skylark rocket (SL 1206) launched from Woomera at 0535 UT on 26th November 1973. One of the active regions studied (12624) was observed about 60 minutes after the peak of an importance – N class CO flare.

X ray probes in action

Ariel 5, the British designed x ray satellite, was launched successfully from the San Marco platform off the Kenyan coast in October, atop a NASA Scout rocket. The mission commenced just eight days after the equally successful flight of a Skylark rocket carrying x ray instruments.

The Interstellar Medium in the Direction of the Gum Nebula

High resolution (⁠|$d\lambda\simeq0.3$| Å) ultraviolet spectra of |$\gamma^2$| Vel and ζ Pup, obtained from a star-stabilized Skylark rocket flight, have been used to study the interstellar gas in the direction of the Gum nebula. The observations confirm the existence of a large H II region in the line of sight and also give evidence for the existence of small localized regions of high gas density (∼ 104 cm−3). All of the elements observed in the interstellar gas are underabundant relative to hydrogen.

Further Observations of the Structure of the Chromosphere-Corona Transition Region from Limb and Disk Intensities

Further observations of limb and disk intensity ratios of emission lines in the EUV solar spectrum were obtained on a Skylark rocket flight on 5 August 1971. Analysis of the data has shown that the observations support the existence of a steep rise in temperature in the transition region between Te ~ 6 × 104 K and 3 × 105 K. The average absolute height of the transition region above the visible limb has been measured with a greater accuracy than previously possible and is 1700 km ± 700 km. An independent method using arc-length measurements of spectrum lines gives an absolute height of 2100 km ± 850 km. Emission from lines which are optically thick in spicules is observed to extend to heights of 10000 km above the transition region. The observed decrease of Fen emission with height is consistent with current spicule statistics.

Auroral electron fluxes parallel to the geomagnetic field lines

Auroral electron flux characteristics from ∼300 eV to 30 keV were measured with twelve detectors launched on the ESRO Skylark rocket S46/1 from Kiruna, Sweden, on November 10, 1969, at ∼2346 magnetic local time (MLT) into a breakup aurora. The energetic electrons (E ≳ 5 keV) displayed isotropic angular distributions during the entire flight, whereas the lowest-energy electrons (E ≲ 5 keV) were characterized by very anisotropic angular distributions, maximum along geomagnetic field lines when the precipitation was enhanced, ≳108 (cm² s sr keV)−1. The highest value of the ratio between the fluxes measured at 0° and 30° pitch angles was about 40. The energetic and angular distributions thus observed must result from the action of a selective energy mechanism acting mainly on the parallel component of the electron velocity. Experimental results are in agreement with the presence of a parallel electric field along the field lines in the upper ionosphere.

Ultraviolet Spectra of Gamma Velorum and Zeta Puppis

A SKYLARK rocket payload (SL 1111) with a three-axis attitude stabilisation system and instrumentation for high resolution stellar spectroscopy was launched at Woomera, South Australia, at 1030 UT on June 16,1973. The flight was entirely successful, all of the vehicle systems operating correctly and enabling the instrumentation to record high quality ultraviolet spectra of the selected target stars, γ2 Velorum and ζ Puppis.

Rocket observations of electron precipitation in a westward-traveling surge

Twelve auroral electron detectors from 300 ev to 30 kev were launched on the Esro S46/2 Skylark rocket from Kiruna, Sweden, on January 28, 1971, at 2120 MLT into an auroral westward-traveling surge. Data show that the low-energy (E ≲, 5 kev) electron precipitation remains relatively stable throughout the flight; it does not seem to be directly related to the luminous intensity. On the other hand, when the rocket goes through the surge, the high-energy (E ≳ 5 kev) precipitation is greatly increased, and the angular distribution of these electrons, which was anisotropic, being maximum at 90° pitch angle, becomes isotropic. The precipitation mechanism of these electrons in the evening sector during the expansion phase of the magnetospheric substorm is probably associated with instabilities occurring near the equatorial plane in this sector.

The reduction of cosmic-ray induced background in proportional counter rocket experiments

The reduction of cosmic-ray induced background events in proportional counter rocket experiments is discussed for the energy range 1–20 keV. The results from two Skylark rocket flights are presented, one employing scintillator anti-coincidence and the other proportional guard anti-coincidence, both using rise-time discrimination. The results are analysed in terms of the interactions which produce the background.

Further observations of the solar limb spectrum in the region 550?2000 �

Further observations of the ultraviolet spectrum (550–2000 A) of the solar limb and disc were obtained during a Skylark rocket flight on 5 August 1971. These observations have enabled several new spectral lines to be identified and classified.

Neutral Wind Measurement during Daytime in the Thermosphere

A SKYLARK rocket (SL 1023) was launched in the British National Space Research Programme at Woomera Range, S. Australia, at 1130 local time on March 14, 1972. The objective was to make a detailed analysis of the structure of the local daytime ionospheric current system. The study included measurements of vertical profiles of electron density and temperature, electric field, vector magnetic field and neutral wind velocity between 90 and 260 km (vehicle apogee). A detailed report of these measurements will be made at a later date.