On August 2, 1971, at the end of the last EVA of the Apollo 15 mission, Commander David Scott took a few minutes to conduct a classical science experiment in front of the TV camera that had been set up just outside the LM Falcon at the Hadley Rille landing site. Scott, a former Air Force pilot, recreated a famous demonstration often attributed to Galileo (which may or may not have actually been performed by the astronomer in Pisa in 1586) that shows how objects of different masses react the same way to gravity when dropped – that is, they fall at the same rate.
By performing the “acceleration test” in the vacuum environment of space (but where there is still an observable downward pull of gravity) the element of air resistance is negated – especially on such a low-mass and low-density object as a falcon feather – thereby creating a more “pristine” setting for the centuries-old experiment than could ever be achieved on Earth.
According to a report on the mission’s science objectives: “During the final minutes of the third extravehicular activity, a short demonstration experiment was conducted. A heavy object (a 1.32-kg aluminum geological hammer) and a light object (a 0.03-kg falcon feather) were released simultaneously from approximately the same height (approximately 1.6 m) and were allowed to fall to the surface. Within the accuracy of the simultaneous release, the objects were observed to undergo the same acceleration and strike the lunar surface simultaneously, which was a result predicted by well-established theory, but a result nonetheless reassuring considering both the number of viewers that witnessed the experiment and the fact that the homeward journey was based critically on the validity of the particular theory being tested. ” (Joe Allen, NASA SP-289, Apollo 15 Preliminary Science Report, Summary of Scientific Results, p. 2-11. Source.)
Launched on July 26, 1971, Apollo 15 was the first of the “J” missions capable of a longer stay time on the moon and greater surface mobility, thanks to the use of the Lunar Roving Vehicle (LRV).Learn more about the Apollo 15 mission here.
Everyone knows that Apollo 11 commander Neil A. Armstrong was the first human to set foot on the Moon (and if you didn’t know, that occurred on July 20, 1969 – yes, it really happened). It was a momentous, history-making event that many (like myself) consider one of the most impressive achievements of humankind. But oddly enough, even with high-resolution Hasselblad film cameras there on location, there are very few photos showing Armstrong himself on the surface of the Moon. In fact the one above, a panorama captured by fellow Apollo 11 astronaut Buzz Aldrin, really is the best image in existence of Neil on the Moon.
So…why is that?
At 3 p.m. EDT today, July 15 2015, from the Johns Hopkins University’s Applied Physics Laboratory in Laurel, Maryland, the New Horizons team revealed to the world the first high-resolution image acquired of the surface of Pluto. This was obtained during the historic July 14 flyby with New Horizons’ “Ralph” camera, and it’s our very first close-up view of this distant world’s fascinating, beautiful, and surprisingly crater-free surface! Of course more will be coming as the days, weeks, and months pass, and many further studies will be done to determine the nature of all of the features revealed, but for now – enjoy.
This is truly an amazing time in space exploration!
Three days before New Horizons’ closest pass by Pluto and we already have the first final image of the mission: this is the last “best” view we will have of Pluto’s Charon-facing side, as the spacecraft will be acquiring its most detailed images of the planet’s opposite side on July 14.
Pluto and its largest moon Charon are locked together gravitationally, a scenario called tidal locking. The face of one is always aimed at the same face of the other, and they orbit around a point in space (the barycenter) that is located between the two (but closer to Pluto.) Thus the image above shows the side of Pluto that Charon always “sees.”*
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Our Moon is more than just some pretty decoration for the night sky and a place to plant a few flags – it’s also a potential source of valuable raw materials that could someday be used for energy and engineering both on Earth and in space.
If you saw the movie Moon (and if you haven’t I highly recommend it) there was a whole lunar base set up for the extraction of helium-3 from the surface. This isn’t some fantasy “unobtainium” element, it’s a very real isotope that’s rare on our magnetically-shielded Earth but common on the Moon, where it can be easily deposited by the solar wind. Helium-3 alone could make lunar mining ventures economically (or at least environmentally) sensible as it could theoretically power nuclear fusion reactors on Earth with virtually no radioactive waste products. (Read more here and here.)
According to a 2009 AFP article “Reserves of helium-3 on the moon are in the order of a million tons, according to some estimates, and just 25 tons could serve to power the European Union and United States for a year.”
But how could we obtain helium-3 and other valuable lunar resources, why do we need them and what effect might those operations have on the Moon we all know and love? There’s an infographic for that, produced by consulting firm 911 Metallurgist and designed by NeoMam Studios. Check out the full graphic below and decide if you think we should be aiming for the Moon…
Do you love to look up at the Moon? Well so does NASA’s Curiosity rover! Feel free to correct me if I’m wrong (I have not confirmed this) but this appears to be an image of Phobos, the larger of Mars’ two small moons, imaged by Curiosity’s Mastcam on mission Sol 1002 (June 1, 2015). I spotted it while looking though some raw images on JPL’s MSL mission page.
Phobos is a very small world, only about 16 miles (26 km) across, and orbits Mars at 5,840 miles (9,400 km) altitude. Curiosity has imaged it before, once actually crossing in front of the Sun during an eclipse event on Aug. 20, 2013.
Both Phobos and its smaller, more distant sibling Deimos have been imaged together by Curiosity as well, during an occultation on Aug. 1, 2013. See an animation of those observations here.
Planned observations of Phobos help scientists more precisely determine its orbit.
See a color image of Phobos acquired by the HiRISE camera aboard Mars Reconnaissance Orbiter here.