Of Rocks and Spin At Bennu

Microgravity Matters and Near Earth Objects

Tags asteroids, spin, Bennu, NASA, gravity, microgravity, ORISIS-REx


When I was a child, I earned candy money from my father in a unique way. Candy talk somehow seems appropriate in this post-election week where the eye candy and repetitive brand pitches are inescapable. “Watch the shiny object” is an ever-present political rant. These days we could all live well if we were simply paid a prorated rate to endure the current steady state of political ads.

The First Space Race

Back in the day, I got paid to spot orbital satellites and meteors. Mind you satellite sightings paid more than falling rocks from space. A smart kid could manage to figure out that some things go round and round and come back to pay rewards again and again. Nah. I really wasn’t that good at it, but you get the idea.

In elementary school I was incentivized to learn the difference between the DOD sponsored Vandenburg polar orbital group, the Soviet group, and the more well-known Cape Canaveral orbital paths. Most of what I earned was happily invested in Mars and Hershey chocolate futures, if you catch my drift. Ok. I still have a hankering for a handful of candy corn now and then.

My father was rightly proud of what he did for a living back then. Most of the US satellites the I could spot on those warm summer evenings and cold winter nights contained solar cell arrays that the company my father worked for supplied.

Space is a Nasty Place

What do you know? I was the only kid I knew who listened to World Series games on a solar cell powered transistor radio. Batteries not included. Eheh. Way cool. I believe this company marketing and promotional item survived in working condition until after I graduated high school.

Watching Antiques Roadshow today makes me wonder how much a branded limited first production run edition of a Telstar solar cell radio would be worth today on the auction block. Dang. It seems that Telstar 1 and 2 lasted longer in orbit than the radio. Technology moves quickly. The pair quickly became space junk. The Telstar communication satellites did not run so well or as long as that solar powered radio.

Space is a nasty place. The Sun is a harsh mistress (grin) that blows and, as they say, gravity sucks.

Speaking of Space Junk

This video is an interesting tour of the surface of the large pile of space rocks called Bennu. Talk about an interesting local coordinate system and an expensive lesson on how to name a pile of rocks.

 

An ORISIS-Rex Tour of the Asteroid Bennu

Why modern scientists insist on obscure mythological naming conventions is not beyond me. Perhaps this habit comes from academic political angst - Never give a naming credit to a living person.

Let’s be perfectly clear about a couple of really interesting thing about Bennu.

No scientist or engineer working on the ORISIS-Rex NASA project seriously thought or seriously considered that an asteroid would or could look like this pile of space rocks and rubble until the mission vehicle arrived. OMG.

The experts expected a sandy beach of well-behaved ancient and dusty regolith wrapped around a big rock - Think of Moon or Mars dust or maybe better yet the sand at the beach at Galveston Tx. The almost misadventure at Bennu proves that microgravity rules. More about that in a bit.

Mind you NASA had already spent a couple of hundred million dollars designing and building an air cleaner like device to trap the expected sand and dust called the Regolith Explorer.

A major goal of the ORISIS-Rex mission was/is to return a substantial sample of asteroid material to Earth. Ok. NASA did end up with an air cleaner device like the ones in your car – a not-so-simple tool manned by some stunning robotic controls.

Here’s the NASA promotional Bennu Triumph short press release video…

 

OSIRIS-REx Touches Asteroid Bennu

“Dang. We should have just sent a Dyson or a Shark vacuum cleaner.”

The NEO and Apollo object Bennu makes a “close pass” with Earth about every six years. Bennu was about 200 million miles from Earth when they pulled off the Touch. Space is a big and not so empty place. Eheh.

Not said in that video…The touch NASA remembers turned out to be about 15” inches deeper than they expected. OSIRIS-REx bit off more than its fancy air cleaner attachment could chew – NASA currently believes/hopes they got more bigger chunks that they counted on. NASA hopes most of the sample makes it back to Earth in a next year on Sept. 24, 2023 in one piece…so to speak.

Perhaps, that sample will be worth more than Moon rocks. Asteroid samples are rarer.

Touch A Pet Rock Day

Hmmm?
In advance of the official Touch the Asteroid Day, NASA and PBS put together a one-hour Nova special to popularize and to publicize the OSIRIS-REx mission.

Touching the Asteroid

Like I said I am a space, asteroid, and comet geek. Yet, I caught the first run of this Nova show almost by accident by channel surfing.

The show is typical, current PBS Nova fare - More than a bit of popularized and semi-scripted pseudo-drama on top of some really interesting deep space science and engineering.
Worth the time. Enjoy.

For the Seriously Interested

Microgravity interests me. Why? Recent discoveries in microgravity effects have revolutionized how we think about the solar system and other important things like the formation of protostars. I wasn’t really all that surprised by the apparent pile of rocks that is Bennu - at least on the surface. Just sayin’. There were orbiting big Jupiters and other junk long before our solar system act one.

The current available science and technology only allow us to analyze the general surface material content of asteroids, comets, etc. via the magic science of light. Most of the relatively bigger small stuff in a planetary system has been collecting smaller bits and pieces for a very long time.

Whatever gets ground into smaller chunks will tend to infect all the available surfaces in the surrounding neighborhood. This effect explains why we own a Dyson or a Shark in the first place.

We ended up with the current Asteroid Family Groups theory. Note the mention and references to Vesta Group materials on Bennu in the videos.

The OSIRIS-REx mission should remind us all that you have to be there to get there.

We still suffer from what some revisionists these days might call the Columbus Syndrome.
Roberto. We rediscovered the East Indies. Let’s call them the West Indies and enslave everybody.”

In historical fairness to Christopher, he states that he thought very differently.
He named the new land San Salvador or Holy Savior.
We might translate this to – “Thank God” or better yet “Sweet Jesus”.
Some late-medieval Genoese sailor humor translated into politically correct formal Spanish.
The island name is coupled with an understandable sense of relief and vindication.

The Important Matter of Spin

My favorite recent small space object factiod…
Why do space rocks like Bennu spin?

We assume spin is impact related because we continue to worship Sir Newton and because that may at times be true.
In the long run the most likely and common cause for spin is the pressure of the ferocious solar wind.
Photons and other radiation per square meter inside the heliosphere piles up seriously.
Plainly put, some of the stored energy goes into the spinning the rocks.

The Inertia of Spin

The future of asteroid mining will depend on how well we can learn to harness and steal the inertia of spin.

Sweet Jesus. That’s a loaded statement.