On This Day in Space Exploration

  January 31 31 January 1862 Alvan Graham Clark. Credit: Thomas Rice Burnham On January 31, 1862, American telescope-maker and astronomer Alvan Graham Clark (1832–1897) made the first observation of Sirius B while testing a new 18.5-inch (470 mm) aperture refractor telescope. Sirius B is the nearest known white dwarf, at 8.6 light years from the Sun. Its existence was deduced in 1844 by German astronomer Friedrich Wilhelm Bessel (1784–1846), from changes in the proper motion of Sirius. Sirius B has a mass of  1.02  M ☉  ( 102% of the Sun's), a nd a diameter of 12,000 km – nearly that of the Earth. It's  surface temperature is 25,200 K.  The star is primarily composed of a carbon–oxygen mixture that was generated by helium fusion in the progenitor star.  This is overlaid by an envelope of lighter elements, with the materials segregated by mass because of the high surface gravity.  The outer atmosphere of Sirius B is now almost pure hydrogen an...

  January 30 30 January 1964 Model of Ranger Block III spacecraft. Credit: NASA/JPL-Caltech On January 30, 1964, Ranger VI lunar probe, the first in the series of four Ranger Block III spacecraft, was launched. It carried a suite of six TV cameras capable of taking 300 pictures a minute, and was expected to transmit high-resolution photographs of the lunar surface in the last minutes of the flight until the impact. The spacecraft impacted the Moon as planned on February 2, 1964, but a TV power system failure prevented it from transmitting any images of the Moon's surface. Ranger VI under construction, September 24, 1963. Credit NASA JPL-Caltech Full Description from NASA Space Science Data Coordinated Archive: Ranger 6 was designed to achieve a lunar impact trajectory and to transmit high-resolution photographs of the lunar surface during the final minutes of flight up to impact. The spacecraft carried six television vidicon cameras, 2 full-scan cameras (channel F, o...