Technology readiness assessments: A retrospective

The development of new system capabilities typically depends upon the prior success of advanced technology research and development efforts. These systems developments inevitably face the three major challenges of any project: performance, schedule and budget. Done well, advanced technology programs can substantially reduce the uncertainty in all three of these dimensions of project management. Done poorly, or not at all, and new system developments suffer from cost overruns, schedule delays and the steady erosion of initial performance objectives. It is often critical for senior management to be able to determine which of these two paths is more likely—and to respond accordingly. The challenge for system and technology managers is to be able to make clear, well-documented assessments of technology readiness and risks, and to do so at key points in the life cycle of the program.In the mid 1970s, the National Aeronautics and Space Administration (NASA) introduced the concept of “technology readiness levels” (TRLs) as a discipline-independent, programmatic figure of merit (FOM) to allow more effective assessment of, and communication regarding the maturity of new technologies. In 1995, the TRL scale was further strengthened by the articulation of the first definitions of each level, along with examples (J. Mankins, Technology readiness levels, A White Paper, NASA, Washington, DC, 1995. [1]). Since then, TRLs have been embraced by the U.S. Congress’ General Accountability Office (GAO), adopted by the U.S. Department of Defense (DOD), and are being considered for use by numerous other organizations. Overall, the TRLs have proved to be highly effective in communicating the status of new technologies among sometimes diverse organizations.This paper will review the concept of “technology readiness assessments”, and provide a retrospective on the history of “TRLs” during the past 30 years. The paper will conclude with observations concerning prospective future directions for the important discipline of technology readiness assessments.     

Solar UV irradiance variation during cycles 22 and 23

The Solar Ultraviolet Spectral Irradiance Monitor (SUSIM) aboard the Upper Atmosphere Research Satellite (UARS) has been measuring solar UV irradiances since October 1991, a period which includes the decline of solar cycle 22 followed by the rise of cycle 23. Daily solar measurements include scans over the wavelength range 115–410 nm at 1.1 nm resolution. As expected, the measured time series of UV irradiances exhibit strong periodicities in solar cycle and solar rotation. For all wavelengths, the UV irradiance time series are similar to that of the Mg II core-to-wing ratio. During solar cycle 22, the irradiance of the strong Ly- line varied by more than a factor of two. The peak-to-peak irradiance variation declined with increasing wavelength, reaching 10% just below the Al edge at 208 nm. Between the Al edge and 250 nm the variation was 6–7%. Above 250 nm, the variation declines further until none is observed above 290 nm. Preliminary results for the first portion of cycle 23 indicate that the far UV below the Al edge is rising at about the same rate as the Mg II index while the irradiances in the Ly- emission line and for wavelengths longer than the Al edge are rising more slowly — even after accounting for the lower level of activity of cycle 23.     

Modeling large solar flares

The basic ideas to model the large solar flares are reviewed and illustrated. Some fundamental properties of potential and non-potential fields in the solar atmosphere are recalled. In particular, we consider a classification of the non-potential fields or, more exactly, related electric currents, including reconnecting current layers. The so-called ‘rainbow reconnection’ model is presented with its properties and predictions. This model allows us to understand main features of large flares in terms of reconnection. We assume that in the two-ribbon flares, like the Bastille-day flare, the magnetic separatrices are involved in a large-scale shear photospheric flow in the presence of reconnecting current layers generated by a converging flow.     

Solar maximum mission experiment: Ultraviolet spectroscopy and polarimetry on the solar maximum mission

We describe the Ultraviolet Spectrometer and Polarimeter (UVSP) on the Solar Maximum Mission (SMM) spacecraft. The instrument, which operates in the wavelength range 1150 – 3600 Å, has a spatial resolution of 2–3 arc sec and a spectral resolution of 0.02 Å FWHM in second order. A Gregorian telescope, focal length 1.8 m, feeds a 1 m Ebert-Fastie spectrometer. A polarimeter comprising rotating Mg F₂ waveplates can be inserted behind the spectrometer entrance slit and allows all four Stokes parameters to be determined. The observing modes include rasters, spectral scans, velocity measurements, and polarimetry. Finally, we present examples of initial observations made since launch.     

On electromagnetic phenomena in Mercury’s magnetosphere

Mercury has a small but intriguing magnetosphere. In this brief review, we discuss some similarities and differences between Mercury’s and Earth’s magnetospheres. In particular, we discuss how electric and magnetic field measurements can be used as a diagnostic tool to improve our understanding of the dynamics of Mercury’s magnetosphere. These points are of interest to the upcoming ESA-JAXA BepiColombo mission to Mercury.     

Atomic and molecular hydrogen in interstellar space

This paper reviews the present state of knowledge of the abundances and physical state of interstellar atomic and molecular hydrogen. Much new data in this area have been obtained in recent rocket observations. There have also been new developments as a result of ground-based infrared and 21-cm observations, and theoretical research.Rocket observations of the Lyman- interstellar absorption line of atomic hydrogen indicate that, in many directions in the sky, atomic hydrogen is up to a factor of 10 less abundant than previously indicated by 21-cm emission measurements. In the direction of the Orion Nebula, most of the absorbing gas appears to be concentrated in the near vicinity of the nebula and to have a temperature considerably lower than the average of 100 K obtained from 21-cm emission measurements. Molecular hydrogen appears essentially absent from the general interstellar medium, as confirmed by theoretical studies of photodissociation processes. However, ground-based infrared and 21-cm studies indicate that the hydrogen in dark dust clouds is mostly molecular.     

Elemental Abundances in Coronal Structures

A great deal of evidence for elemental abundance variations among different structures in the solar corona has accumulated over the years. Many of the observations show changes in the relative abundances of high- and low-First Ionization Potential elements, but relatively few show the absolute elemental abundances. Recent observations from the SOHO satellite give absolute abundances in coronal streamers. Along the streamer edges, and at low heights in the streamer, they show roughly photospheric abundances for the low-FIP elements, and a factor of 3 depletion of high-FIP elements. In the streamer core at 1.5 R·, both high- and low-FIP elements are depleted by an additional factor of 3, which appears to result from gravitational settling. This revised version was published online in June 2006 with corrections to the Cover Date.     

Determination of optimal parameters of a moving wall on airfoil

A problem is posed and solved on determining the optimal parameters of a moving wall installed on the airfoil surface to prevent the boundary layer separation. As the wall parameters, its initial and final position and motion velocity are taken. To solve the problem, the optimization methods with penalty functions are used. The conclusions were drawn on selecting the efficient parameters of the moving wall in terms of the minimum of energy expenditure and friction drag.     

Intensification of heat exchange on the convex surface of an annular channel with continuous flow swirling

In this paper, the results of an experimental study concerning average heat transfer in an annular channel with flow swirling by an endless screw and spherical grooves on the convex surface are presented. Also analyzed is the heat and hydraulic efficiency of grooves application under conditions being considered.