Saturday, October 24, 2020


Space history was written last week when OSIRIS-REx, third planetary scout in the New Frontiers programme (after Juno exploring Jupiter and New Horizons checking Pluto), collected a regolith sample on asteroid belt inhabitant 101955 Bennu. Given the abundance of asteroid candidates, why this one? For starters, it's 'close', sometimes even cutting inside Earth's orbit. It's not rotating too fast, making it far easier to touch down and grab up some dust. And it's a C-type asteroid, in which the C stands for carbonaceous, meaning they are relatively pristine time and space travellers from long passed aeons - Bennu may even contain material from before the Solar System's existence. A more comprehensive list of why Bennu was so sexy can be found here.

OSIRIS-REx (Origins, Spectral Interpretation, Resource Identification, Security, Regolith Explorer) is a NASA asteroid-study and sample-return spacecraft, launched from Cape Canaveral in SEP 2016 on top of an Atlas V rocket. Some specs:

* Dimensions: Length 2.4 m (7 ft 10 in), width 2.4 m (7 ft 10 in), height 3.15 m (10.3 ft) * Width with solar arrays deployed: 6.17 m (20.2 ft) * Power: Two solar arrays generate 1226 to 3000 watts, depending on the spacecraft's distance from the Sun. Energy is stored in Li-ion batteries. * Propulsion system: Based on a hydrazine monopropellant system developed for the Mars Reconnaissance Orbiter, carrying 1,230 kg (2,710 lb) of propellant and helium. * The sample-return capsule will reenter the Earth's atmosphere for a parachute assisted landing. The capsule with encased samples will be retrieved from Earth's surface and studied, as was done with the Stardust mission.

And here is the iconic moment of OSIRIS sampling Bennu's surface. What's utterly amazing is the distance from Earth at which this happened, some 320 million kilometers. Or, as the distance from Earth to Sun is about 150 million kilometers, or 1 Astronomical Unit, this tiny human-made spacecraft did what it was supposed to do at more than 2 AU! As radio signals to steer the craft would take too long - 15 minutes - to reach it, the entire process was fully automatic.

Also via Twitter:

In order to get a relevant sample, OSIRIS-REx had to collect at least 60 grams. If the first attempt's yield at the designated "touch and go spot", dubbed 'Nightingale', was less, a second attempt at another spot was scheduled. However, it turned out that was not necessary:

OSISRIS-REx will now return to Earth and its precious cargo is expected to be available for study somewhere in 2023. That's... a thrilling prospect. As Bennu is over 4.5 billion years old, it means that humanity will be able to study material which already existed from before... the creation of our own Solar System!


Sunday, October 18, 2020


John Atkinson Grimshaw (6 September 1836 – 13 October 1893) was an English Victorian-era romanticist indebted to some extent to the Pre-Rafaelits. The 'Painter of Moonlight' is best known for his nocturnal scenes of urban landscapes.

The Chill of Autumn (1881).

Scarborough Lights (1877).

Good night, have a good start of the week tomorrow.