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It's a small solar system



  The asteroids Ryugu (left) and Bennu (right) are juxtaposed approximately to scale. Soon we will get to know many more miniature worlds like these. (Picture credits: JAXA, left, NASA-GSFC / U-Az, right)

A story of two asteroids: Ryugu (left) and Bennu (right), which are shown side by side approximately on a scale. Ryugu is nearly 1 km wide; Bennu is about 500 meters away. Soon we will get to know many more miniature worlds like these. (Source: JAXA, left, NASA-GSFC / University of Arizona, right)

Many years ago, this magazine belonged to the Walt Disney Corporation, and I sometimes got one of the company's songs in my head: "It's a small world ", The tireless musical accompaniment of the eponymous ride at Disney World in Florida. This song has come back to my mind lately, but in a completely different and more majestic context. We are entering a new stage in solar system exploration that reverses the theme of many previously flipped topics. Big is out and small is in it.

The hottest targets in space are currently comets and asteroids – including asteroid Bennu, now in sight of the ambitious OSIRIS REx probe. The most innovative robot researchers have the size of a briefcase. NASA's newest pivot plan is that the long-term plan to send people back to the Moon and Mars will begin on a modest scale with a series of low-priced, privately-built lunar researchers. Note the mental music: "It's a small solar system (After All)."

To be honest, planet researchers have been working hard to explore the small bodies of the Solar System, at least since Halley's comet near Sun three has passed decades ago. But the effort began in 2014 when the European Space Agency's (ESA) Rosetta probe arrived in the Comet 67P / Churyumov-Gerasimenko, returning dazzling images and data from the rubber-comet. Rosetta also deployed a small lander, Philae, who did not function as planned but greatly enhanced the mission's drama.

In previous spacecraft, comets had been discovered only as fuzzy, cryptic objects. Rosetta made the Comet 67P a world of its own.

The Japanese space agency (JAXA) sent the probe Hayabusa2 not to surpass with four lander in tow to the asteroid Ryugu. In a previous blog post I covered the first results and implications of this mission. Ryugu is shaped like a top and littered with debris. Early views of Bennu show a fascinatingly similar form; Apparently, this is a common result of fast rotation, low gravity, and weak internal structure. OSIRIS-REx will officially arrive in Bennu on December 3rd. We will get to know this 500 meter wide asteroid much better in the next few weeks.

The current doubling of the small asteroids provides only a small indication of what it is coming soon. JAXA plans to continue the DESTINY + mission to Phaethon, a bizarre "rock comet" who appears rocky but throws dust into a meteoric tail. Some of these dust particles hit Earth every year as a Geminid meteorite.

NASA has three very different asteroid missions in the works. Lucy will visit seven different Trojan asteroids, primitive bodies orbiting Jupiter, but traveling in front of or behind the giant planet in its course around the Sun. Psyche explores an object of the same name – a bizarre metallic asteroid, possibly the remnant core of an old, destroyed protoplanet. DART flies an impactor into a small, near-Earth asteroid to test technology for deflecting a body on a collision course. The ESA could send a follow-up mission, Hera, to investigate the consequences of the impact.

This list does not even include possible missions by the Indian and Chinese space agencies. It also does not reflect the real explosion that is likely to follow a few years later – a consequence of the other small trend in space exploration.

  MarCO-B (Wall-E) has taken this amazing picture of Mars immediately after an approach. when it was 7,600 kilometers from the planet. The grid on the right is the communication antenna of the probe. (Credit: NASA / JPL-Caltech)

MarCO-B (Wall-E) made this touching attitude of Mars immediately after approaching when it was 7,600 kilometers from the planet. The grid on the right is the communication antenna of the probe. (Credit: NASA / JPL-Caltech)

Attack of the Cubes

When NASA's InSight Lander landed on Mars last week, an even more significant event took place. I do not want to downplay the importance of the lander. It is a very clever mission that investigates the geophysical origin of Mars by studying the seismology of the planet and the flow of the original heat from within. InSight, however, in many ways follows a now familiar approach, built on the same basic architecture as earlier Mars lander.

What was not known was the InSight Companion, two small probes officially known as MarCO-A and MarCO-B, but lovingly nicknamed Eva and Wall-E. They were built using a commercial, modular design called Cubesat. Almost 1,000 cubesats were launched around the world to conduct focused experiments at low cost. Eva and Wall-E were the first Cubesats to explore space. You can bet they will not be the last.

The MarCO project was primarily a technology experiment to prove that Cubesats are powerful and robust enough to be tens of millions of miles from Earth. They managed to pass data from InSight during and immediately after landing on Mars. Eva and Wall-E also had small, commercial onboard cameras that took unique snapshots of Mars as they flew by. (They do not have their own rocket engines and were never designed to land.) The MarCO project had a budget of only $ 18 million.

  One of the Mars Cubesats prepared by Joel Steinkraus, senior mechanical engineer at JPL. (Credit: NASA / JPL-Caltech / Tyvak / Cal Poly SLO)

One of the Mars Cubesats was prepared by Joel Steinkraus, MarCO Senior Mechanical Engineer at JPL. Yes, it is small. (NASA / JPL-Caltech / Tyvak / Cal Poly SLO)

NASA is planning a bigger test of Cubesats when it makes its first test launch of the space launch system rocket currently scheduled for June 2020. One could not ask for a sharp contrast: the enormous, late, overbudgetary SLS rocket unleashing a fleet of 13 nimble, fast and cheap space explorers.

Most of these Cubesats will fly to the moon. They will work well with NASA's recently announced program to hire private companies to conduct scientific experiments on the Moon. One of the Cubesats, NEA Scout, will follow MarCO into space and navigate this time with a small awning to a near-Earth asteroid (hence "NEA").

Asteroids and Cubesats are natural companions. Landing on a planet requires extensive, complex mechanisms to gently decelerate and land. Small asteroids like Bennu and Ryugu are much easier due to their weak gravity. All you really need to do is fly with them. They can sit up (more like "brushing over") and then take off with almost no energy. Why could even a Cubesat do it? Of course, small bodies and small spacecraft belong together.

The other synergy between asteroids and cubesats consists of volume – or rather abundance. There are more than a million asteroids the size of Bennu or larger. It would be scientifically fascinating to study a large number of them at close range, but it would be madness to try this with a series of $ 800 million missions like InSight. On the other hand, it's easy to imagine sending dozens, even hundreds, of budget cubesats to hover Earth's orbit in the asteroid belt, like a beehive checking the flowers in its neighborhood.

Space resource enthusiasts like Philip Metzger have already outlined concepts in this direction. Last year, a Finnish group showed how a fleet of 50 nanospace aircraft could capture 300 asteroids in about three years, far less than the cost of a single Marslander. Asteroids are an attractive commercial destination because their resources are available – easy on, easy off. Asteroids and comets are also attractive scientific targets, as they survive remnants of the early days of the solar system. Piece by piece, chapter by chapter, they contain the story of our origins.

We will only understand the full course of this story if we put the little pieces together. And … there is this song back in my head.

For space and astronomy news, follow me on Twitter : @coreyspowell


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