Ossiris-REx begins preliminary survey phase ahead of orbital insertion

NASA’s OSIRIS-REx spacecraft after a 2 billion km journey, has reached and is now in orbit around asteroid Bennu.   See previous post.

Below is a series of images taken by OSIRIS-REx at a distance of about 80 km (50 mi.) The images constitute one full revolution of the asteroid.

The spacecraft is now in the Preliminary Survey Phase which began on December 3, 2018, and marks the first time that the OSIRIS-REx spacecraft will operate around the asteroid. The spacecraft will make a total of five passes over the north pole, equator, and south pole at a range of 4.3 miles (7 km). The primary science goals of Preliminary Survey are to estimate Bennu’s mass, refine the asteroid’s spin state model, and generate a global shape model at a resolution of 75-cm.  With this information orbital insertion can be planned and detailed (and close) survey of the asteroid can begin.

SPP-Preliminary-Survey-Poster-12-19-17

This doth remind me

Credit: Origin Unknown. Arc de Triomph, Paris

“HARK! Hark! on yonder distant shore,
The noisy din of war I hear;
The sword’s unsheath’d—the cannons roar,
And Gallia’s sons in arms appear,
‘Tis France, ’tis France, the people cry,
Fighting for sacred Liberty.”    Thomas Spence, 1794

A truly remarkable image of the Arc De Triomph with a  vast crowd of angry French Yellow Jackets.

Notables on Macron 2017:

  • Osborne: “The leadership that France needs.”
  • D. Miliband: “[The] tribune for modernisation in…Europe.”
  • Freeman: “A French JFK.”
  • Cable: “I can offer the same formula.”
  • Lineker: “Boy we could do with a Macron.”

Oh indeed to be so very wrong, in short a time.

Our Star’s sibling – looks like a good candidate

Its 4.5 billion years since our solar system formed in a  gaseous nebula.  These nebula formed from the explosive collapse of stars, larger than Sol, when they have exhausted much of their hydrogen.  These Supernova cast much of their mass into space forming  a gaseous nebula.  These nebula are however large –  much larger than our solar system and are incubators of star formation, sometimes hundreds of stars, much like the glowing nebula in the image below.

NASA, ESA, and the Hubble SM4 ERO Team – http://www.hubblesite.org/newscenter/archive/releases/2009/25/image/e/
Composed of gas and dust, the pictured pillar resides in a tempestuous stellar nursery called the Carina Nebula, located 7500 light-years away in the southern constellation of Carina. Taken in visible light, the image shows the tip of the three-light-year-long pillar, bathed in the glow of light from hot, massive stars off the top of the image. Scorching radiation and fast winds (streams of charged particles) from these stars are sculpting the pillar and causing new stars to form within it. Streamers of gas and dust can be seen flowing off the top of the structure. Hubble’s Wide Field Camera 3 observed the Carina Nebula on 24-30 July 2009. The composite image was made from filters that isolate emission from iron, magnesium, oxygen, hydrogen and sulphur.

Overtime, the varied gravitational environment in the galaxy results in stars formed from the same nebula drifting apart, however they will retain the same composition and have similar spectral characteristics and maybe even be of comparable in size.  Finding these siblings would require a massive star survey.  We would have to know the distance from Earth, the relative speed and direction and the composition.  Given that there are a vast number of stars in our immediate neighborhood –  this is a daunting task.

The Gaia spacecraft is performing just such a  survey of the Milky Way.  Gaia is measuring the distance, velocity and spectral characteristics for a billion stars in our galaxy has now spotted what appears to be a twin (HD186302) of Sol and it has near identical spectral characteristics.  Of the 200,000 stars in the spectral Gaia catalog only one star, HD186302, has near-identical chemistry to Sol.

HD186302 is a G3-Type main sequence star with about same surface temperature as Sol and is about the same age, 4.5 BY.  HD186302 is located 184 light years from Earth,   which sounds like it’s very distant.  However, to achieve this separation if Sol and HB186302 were original 1-2 light-years apart within the nebula it would only require a relative velocity between Sol and HD186302 of 65,000 km/hr since formation to have achieved the current separation.  In galactic terms this is a very realistic relative speed.