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We report on an evaluation of the effectiveness of Project ARIES, an astronomy-based physical science curriculum for upper elementary and middle school children. ARIES students use innovative, simple, and affordable apparatus to carry out a wide range of indoor and outdoor hands-on, discovery-based activities. Student journals and comprehensive teacher materials aid in making the science content accessible to students based on their shared experiences and observations. Approximately 750 Grades 3-6 students in ARIES (or treatment) classrooms are compared with approximately 650 Grades 4-6 students in control classrooms through a series of open-ended assessment measures, using a pretest and posttest format. A detailed analysis by item measures the gain in treatment and control groups. We identify concepts where the ARIES approach is more effective, where both are equally effective, and where neither results in much learning. (The ARIES approach was never less effective.) Although learning is in evidence for both control and treatment groups, overall, the ARIES students achieve roughly four times the gain of their control counterparts. In particular, ARIES students had much greater gains for the concepts that the control students found most difficult. (Contains 1 table and 2 figures.)

In November 2005, we observed the moons of Mars using the Arecibo 2380-MHz (13-cm) radar, obtaining a result for the OC radar albedo of Phobos (0.056 [+ or -] 0.014) consistent with its previously reported radar albedo and implying an upper bound on its near-surface bulk density of 1.6 [+ or -] 0.3 g [cm.sup.-3]. We detected Deimos by radar for the first time, finding its OC radar albedo to be 0.021 [+ or -] 0.006, implying an upper bound on its near-surface density of 1.1 [+ or -] 0.3 g [cm.sup.-3], consistent with a high-porosity regolith. We briefly discuss reasons for these low radar albedos, Deimos' being possibly the lowest of any Solar System body yet observed by radar. Keywords: Mars, satellites; Radar observations; Regoliths

We describe Arecibo (2380 MHz, 12.6 cm) Doppler-only radar detections of near-Earth Asteroids 1915 Quetzalcoatl, 3199 Nefertiti, 3757 (1982 XB), and 4034 (1986 PA) obtained between 1981 and 1989. Estimates of the echo spectral bandwidths, radar cross-sections, and circular polarization ratios of these objects constrain their sizes, radar albedos, surface roughnesses, taxonomic classes, rotation periods, and pole directions. Our radar constraints on the diameters of Quetzalcoatl and Nefertiti are most consistent with sizes determined using thermal-radiometry and the Fast Rotation Model (FRM): this consistency may indicate that these asteroids have surfaces of high thermal inertia (i.e., little or no regolith). Constraints on Quetzalcoatl's radar albedo rule out a 'metallic M' classification. The radar constraints for Nefertiti are inconsistent with a rotation pole published by Kaasalainen et al. (2004, Icarus 167, 178). Our estimates of 1982 XB's size are consistent with previously published estimates. The radar bandwidth of 1986 PA places an upper bound of about 24 h on its rotation period. Keywords: Asteroids; Radar

We report Doppler-only (cw) radar observations of basaltic near-Earth asteroid 3908 Nyx obtained at Arecibo and Goldstone in September and October of 1988. The circular polarization ratio of 0.75 [+ or -] 0.03 exceeds ~90% of those reported among radar-detected near-Earth asteroids and it implies an extremely rough near-surface at centimeter-to-decimeter spatial scales. Echo power spectra over narrow longitudinal intervals show a central dip indicative of at least one significant concavity. Inversion of cw spectra yields two statistically indistinguishable shape models that have similar shapes and dimensions but pole directions that differ by ~100[degrees]. We adopt one as our working model and explore its implications. It has an effective diameter of 1.0 [+ or -] 0.15 km and radar and visual geometric albedos of 0.15 [+ or -] 0.075 and [0.16.sup.+0.08.sub.-0.05]. The visual albedo supports the interpretation by D. P. Cruikshank et al. (1991, Icarus 89, 1-13) that Nyx has a thermal inertia consistent with that of bare rock. The model is irregular, modestly asymmetric, and topographically rugged. Key Words: asteroids; radar.

Arecibo radar echo spectra show the Q-class asteroid 1862 Apollo to have an elongation within 10% of 1.27, a pole-on silhouette with an average dimension of about 1.7 km, and disc-integrated radar properties that are typical for radar-detected near-Earth asteroids. Key Words: asteroids; radar.

We describe Doppler-only radar observations of near-Earth asteroids 2062 Aten,2101 Adonis, 3103 Eger, 4544 Xanthus, and 1992 QN that were obtained at Areciboand Goldstone between 1984 and 1996. Estimates of the echo spectral bandwidths,radar cross sections, and circular polarization ratios of these objects constraintheir pole-on breadths, radar albedos, surface roughnesses, taxonomic classes,rotation periods, and pole directions. Aten's bandwidth is consistent with itsradiometrically determined diameter of 0.9 km. Adonis has a rotation period P [lessthan or equal to] 11 h and an effective diameter (the diameter of a sphere withthe same projected area as the asteroid) between 0.3 and 0.8 km. The radarproperties of Adonis suggest it is not a member of taxonomic classes C or M. Theeffective diameter of Xanthus is between 0.4 and 2.2 km with a rotation period P[less than or equal to] 20 h. Echoes from 1992 QN constrain the asteroid's pole-onbreadth to be [greater than or equal to] 0.6 km and probably exclude it from theC and M taxonomic classes. The strongest Eger echoes are asymmetric with bandwidthsthat set lower bounds of 1.5 and 2.3 km on the minimum and maximum breadths of theasteroid's pole-on silhouette. If Eger is modeled as a 1.5 x 2.3 km biaxialellipsoid, then its effective diameter for an equatorial view is 1.5 km end-on and1.9 km broadside or pole-on, implying a geometric albedo smaller than publishedvalues but still consistent with a classification as an E-type object. Thenear-unity circular polarization ratios of Adonis, Eger, and 1992 QN are among thehighest values measured for any asteroid or comet and suggest extreme near-surfaceroughness at centimeter to meter scales. Key Words: asteroids; radar; Aten; Adonis; Eger; Xanthus.

Asteroids 1 Ceres, 2 Pallas, and 4 Vesta were observed with the 13-cm Arecibo radar and the 3.5-cm Goldstone radar during several apparitions between 1981 and 1995. These observations help to characterize the objects' surface properties. Echoes from Ceres and Pallas are [approximately]95% polarized ([[Mu].sub.C] = [[Sigma].sub.SC]/[[Sigma].sub.OC] [approximately equal to] 0.05) in the sense expected for specular (mirror) reflection yet broadly distributed in Doppler frequency, thus revealing surfaces that are smoother than the Moon at decimeter scales but much rougher (rms slopes > 20 [degrees]) on larger scales. Slopes on Ceres appear to be somewhat higher when viewed with the 3.5-cm wavelength, a trend that is observed for the terrestrial planets and the Moon. In contrast, echoes from Vesta are significantly depolarized, indicating substantial near-surface complexity at scales near 13 cm ([[Mu].sub.C] = 0.24 [+ or -] 0.04) and 3.5 cm ([[Mu].sub.C] = 0.32 [+ or -] 0.04), which is probably a consequence of Vesta's relatively strong basaltic surface material and may be a signature of large impact features inferred to be present on the surface. The low radar albedos of Ceres [Mathematical Expression Omitted] and Pallas [Mathematical Expression Omitted] are in the range expected for surfaces with a carbonaceous chondrite mineralogy. Pallas' distinctly higher albedo implies a [approximately]35% higher surface density, which could result from a lower regolith porosity and/or a higher specific gravity (zero-porosity density). Given a porosity of 45%, the specific gravities of the surface materials on Ceres and Pallas would be [approximately]2.3 and [approximately]3.0 g [cm.sup.-3], respectively, which would be consistent with (1) the presence of an additional silicate component on Pallas' surface (as inferred from spectroscopic observations) and (2) recent mass estimates, which suggest a higher mean (volume-averaged) density for Pallas than for Ceres.

Radar observations of the main-belt asteroids 7 Iris, 9 Metis, 12 Victoria, 216 Kleopatra and 654 Zelinda were carried out at Arecibo Observatory between 1980 and 1989. They reveal large-scale topography in all the targets. Meanwhile, the data was combined with available information culled from radiometric, lightcurve and occultation observations to develop inferences about their sizes, shapes, spins and surface properties.

We report Doppler-only (cw) radar observations of near-Earth Asteroid 2100 Ra-Shalom obtained at the Arecibo Observatory using a transmitter frequency of 2380 MHz (12.6 cm) on 1984 Aug. 18-22. Weighted and filtered sums of cw echoes achieve a maximum signal-to-noise ratio of 74 and cover the asteroid in rotation phase. A weighted sum of all cw spectra gives an opposite circular (OC) radar cross section of 1.13 [+ or -] 0.40 [km.sup.2] and a circular polarization ratio of 0.31 [+ or -] 0.02. Inversion of echo edge frequencies yields a convex hull with an elongation (maximum breadth/minimum breadth) of 1.15 [+ or -] 0.03 and places a lower bound on the maximum pole-on dimension of 2.4 km/cos [Delta], where [Delta] is the angle between the radar line-of-sight and the asteroid's apparent equator. Ra-Shalom has one of the least elongated pole-on silhouettes of the near-Earth asteroids for which similar shape information from radar observations is available. Ra-Shalom's effective diameter (diameter of a sphere with equal cross-sectional area) is constrained to a range of 2.4-3.6 km. We use a two-component radar scattering model to remove the 'diffuse' contributions from Ra-Shalom's radar cross section and obtain a surface bulk density estimate of 1.1-3.3 g [cm.sup.-3]. When compared with reported bulk densities and porosities of meteorites, our results are consistent with either: (1) a C-class asteroid with carbonaceous-chondritic composition, effective diameter 2.6-3.6 km, and surface porosity [is less than] 70%; or (2) an S-class asteroid with ordinary-chondritic or stony-iron composition, effective diameter 2.4-2.6 km, and little or no surface regolith. Ra-Shalom's near-surface roughness appears to be globally heterogeneous. [C] 2000 Academic Press Key Words: asteroids; radar; surfaces, asteroids; asteroids, composition; asteroids, Ra-Shalom.

We report detailed results of Arecibo and Goldstone radar observations of 30 mainbelt asteroids (MBAs) during 1980-1995. In addition to estimates of radar cross section, radar albedo, and circular polarization ratio, we obtain new constraints on pole direction for several asteroids, with those for 21 Lutetia being particularly restrictive. We carry out statistical analyses of disk-integrated properties (radar albedo and polarization ratio) of all 37 radar-observed MBAs. M asteroids seem to have higher radar albedos and a wider range of albedos than do asteroids from the other taxonomic classes; there is no evidence that C and S MBAs have different albedo distributions; and there is some suggestion, worthy of future study, that primitive B, F, G, and P asteroids are not as radar-bright as C and S objects. There is no statistically significant evidence that different taxonomic classes have different polarization ratio distributions, despite suggestions to the contrary based on visual inspection of these distributions. The similarity between the C and S albedo distributions implies similar near-surface regolith bulk densities. The hypothesis of ordinary chondritic composition for the S-class asteroids is reasonably consistent with the radar data, provided that these asteroids have typical lunar porosities. Nevertheless, it is possible that some of these targets have high-porosity regoliths of stony-iron composition. Our M-class sample presumably contains both metallic objects (such as 216 Kleopatra and, probably, 16 Psyche) and less metallic objects. Key Words: asteroids; radar.