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Assessing the Asteroid Factor

I’ve always thought that the biggest driver for our next steps in space is the presence of asteroids. Asteroids affect us in two powerful ways, the first being that they are sources of potential wealth for companies like Deep Space Industries and Planetary Resources, as commercial operations use robotics and eventually humans to extract water and precious metals. Likewise significant is that near-Earth asteroids are a reminder that developing the tools for altering an asteroid trajectory is a good insurance policy for planetary protection.

Asteroids go past us all the time. I count eight that will move past the Earth between now and October 1, the closest — 2015 SO2 and 2015 DS53 — moving within 17 lunar distances. There’s nothing to worry about in this list, as all have zero chance of impacting the Earth. Looking ahead to the first 20 days of October, the closest pass will be by asteroid 462959, at 15 lunar distances. A lunar distance is 384,401 kilometers, and it’s how the Minor Planet Center tabulates these things. I’m also using the MPC’s assessment of impact risks.


Image: The Near-Earth asteroid Itokawa, from which the Japanese Space Agency (JAXA) returned samples in its Hayabusa mission. Credit: JAXA.

Asteroid impacts make for sensational speculation and the occasional overwrought movie, but I’d suggest the best approach to them is simple prudence. We have a mission — OSIRIS REx — on its way to an asteroid called Bennu to make numerous scientific investigations, teaching us about the early history of the Solar System. But the mission will also help us understand the factors that influence an asteroid’s trajectory, such as the Yarkovsky effect, which can slightly alter a small object’s movement because of the uneven heating it can experience. Learning more about such factors suggest better ways to nudge any errant asteroid in the future.

What I really favor is simply keeping asteroids in focus and educating the public about what we’re learning, so that we can get past the sensationalism and make better choices about future missions. It’s useful on that score to point to the Minor Planet Center’s Asteroid Data Explorer site, which allows viewers to quickly drill down into the actual data. If you want to rank asteroids by size, orbital period or closest approach, you can quickly summon up the needed information, with adjustable filters in place for fine-tuning. You can also rank nearby objects in terms of their potential for impact, invariably slight, but a number we always want to keep refining.

Enter ‘The Daily Minor Planet’

Operating at the Smithsonian Astrophysical Observatory, the Minor Planet Center tracks not just near-Earth objects but also comets and the outer satellites of the major planets. As to the term ‘minor planet’ itself, it refers to objects orbiting the Sun that are neither planets nor comets, which can be anything from a dwarf planet like Pluto to a Kuiper Belt Object or an asteroid, trojan or centaur. These turn up more quickly than I would have suspected, with the MPC listing 477 such objects discovered just this month. 45 Near-Earth Objects turned up in the same period, with 1244 NEOs discovered so far in 2016.

2015 DS53, a Near-Earth Object, passes within those 17 lunar distances I mentioned above in the early morning UTC on September 22. The list of close approaches maintained on the MPC site is a fascinating thing to track, reminding us how much our view of the Solar System has changed in the past half century. Few people in the 1950s would have imagined such a debris-laden system, with another belt of material outside the most distant known planet, and a vast halo of comets beyond that. And few would have thought there were so many NEOs.

As the Minor Planet Center reminds us, a known asteroid passes within a few million miles of our planet just about every day. And it has just introduced yet another way of tracking these through an online service called the Daily Minor Planet, which is being developed both by the MPC and volunteers from Oracle Corporation. Asteroid updates go straight to your inbox. Astronomer Matt Holman, director of the MPC, sees the project as an educational resource:

“Most people don’t realize how common asteroid flybys are. We want the Daily Minor Planet to educate readers in an entertaining way, so the next time they see a doom-and-gloom asteroid headline, they’ll know where to go to find the facts.”

This is an outreach project worth keeping an eye on. You can subscribe here. And I think Holman has it right when he refers to ‘asteroid headlines.’ The facts invariably knock the pins out from under the sensationalists who try to milk every natural phenomenon for controversy, but having a widely distributed fact-checking source like this one should tamp all that down.

What we need about asteroids is information and careful analysis. If some entrepreneurs are right, they’re going to play a large role in creating new wealth one day, and if I’m right, they’re going to act as a spur to help us develop the needed technologies to reach them quickly. What we learn will inevitably pay dividends in case we do discover a serious threat, which is why asteroids and their potential should play a major role in an informed space policy.


Comments on this entry are closed.

  • DJ Kaplan September 21, 2016, 13:01

    We need to advance the art of planetary asteroid protection. For some reason, few are willing to fund the protection of life on earth (what’s the payoff anyway?). We need to rely on funds for developing asteroid science from industry. But can we be sure that their scientific advances will help the cause of asteroid protection? Capital does not necessarily have a conscience.

  • ljk September 21, 2016, 14:05

    Project RAMA: Turning Asteroids Into Catapult-Powered Analog Spacecraft

    By Evan Ackerman

    Posted 20 Sep 2016 | 13:00 GMT

    Tech Talk
    Space Flight

    Project RAMA: Turning Asteroids Into Catapult-Powered Analog Spacecraft
    By Evan Ackerman
    Posted 20 Sep 2016 | 13:00 GMT

    Given how expensive it is to lift anything into space from the surface of the Earth, the future of efficient and affordable space travel may be dependent on using the resources that are already up there. Space may seem big and empty, and it mostly is, but there’s enough raw material floating around out there in the form of asteroids and comets to keep us going for eons. The trick is going to be rounding these asteroids up and bringing them somewhere they can be of use without spending so much fuel on the process that the effort is rendered pointless.

    Made In Space is a company that develops technology for, you guessed it, making stuff in space. For example, they’ve got 3-D printers aboard the International Space Station that make tools, and they’ve experimented with turning simulated regolith (Moon dust) into a material that can be 3-D printed into useful things. With funding from NASA’s Innovative Advanced Concept Program, Made in Space has been exploring a fairly wild idea: To gather the raw material for all of our making-in-space needs, Made in Space wants to send small “seed craft” to near-Earth asteroids with the aim of turning them into giant spacecraft that will fly themselves back to Earth to be mined.

    Full article here:


    To quote:

    What Made in Space wants to do with Project RAMA*, short for Reconstituting Asteroids into Mechanical Automata, is to make asteroids into self-assembled, self-contained, self-propelled, fully autonomous spacecraft. If they can pull this off, it would mean that the small seed craft sent to an asteroid would be equipped to use materials on the asteroid itself to manufacture computers, guidance systems, engines, and enough energy to induce the asteroid to use its own mass to propel itself back to Earth’s immediate neighborhood. Then the seed craft would move on to the next asteroid to repeat the process.


    The hardest part of all of this is going to be designing the seed craft. It’ll have to be incredibly capable, with the ability to not just 3-D print things using whatever materials it finds, but also to 3-D print more (analog) 3-D printers to speed up the process. Fortunately, we know how to do this, too. You can imagine the seed craft setting down on an asteroid, scooping up some regolith, and then printing out an analog 3-D printer pre-programmed for self-replication. Eventually, it would switch over to printing gears and punchcards and catapult parts, and when it had everything it needed, the seed craft would become the assembler. Once everything is put together, the seed craft would do the equivalent of flipping the “on” switch, then leave the asteroid to pilot itself back to Earth.

    As fantastical as it sounds, most of the fundamental technologies to make Project RAMA happen already exist, which is probably why NASA is funding it. The goal of this phase 1 study is understanding how the seed craft would have to work, defining requirements, and building a technological roadmap. If everything goes perfectly, a seed craft could potentially be sent to a near-Earth asteroid in the early 2030s.

    *RAMA is an homage to Rendezvous with Rama, an excellent science fiction novel written by Arthur C. Clarke.

    • DJ Kaplan September 22, 2016, 13:03

      I can see that the biggest challenge is to “scoop up some regolith” and make aerospace-quality materials. It’s hard enough to find mil-spec materials and vendors here on Earth. :)

    • Daniel Suggs September 22, 2016, 19:41

      The article says they could throw away up to 60% of the asteroid mass for propellant. Wont the ‘thrown away’ parts become numerous additional asteroids on new orbits and more likely to intercept Earth?

      • ljk September 26, 2016, 9:00

        Let us hope it will be used for other purposes rather than just literally thrown away.

      • ljk September 26, 2016, 10:12

        The “floating” space colonies envisioned in the 1970s were supposed to be built by materials lofted from Luna and presumably the planetoids, so the “refuse” could be used for that as well:


  • Hop David September 21, 2016, 15:50

    A problem with the most accessible asteroids is rare launch windows.

    For low delta missions we look for asteroids with a semi-major axis of 1 A.U.

    But synodic period is
    (Asteroid Period * Earth Period)/(Asteroid period – Earth period)

    As an asteroid’s semi-major axis approaches 1 A.U. it’s period approaches 1 year. As the asteroid’s period gets closer to 1 year, the denominator get’s closer to zero and the synodic period zooms to infinity.

    And it gets worse. Most folks use Shoemaker and Helin’s paper for calculating delta V to NEAs. This assumes rendezvous during the asteroid’s aphelion. Thus launch windows are even less frequent than synodic.

    A way to get around this is to park an asteroid in lunar orbit. This can be done for .2 km/s or even less. When a rock is in lunar orbit, launch windows are constantly open, trip time is less than a week and light lag latency is around 3 seconds. This enables supply lines to a mine as well as frequent opportunities to export mined commodities.

    In the near term, water is the most likely asteroidal commodity. Mass fractions mandated by high delta V budgets make economic space transportation virtually impossible. But an extraterrestrial propellent source would break delta V budgets into smaller chunks and thus break the exponent in Tsiolkovsky’s rocket equation.

    • Alex Tolley September 21, 2016, 17:52

      You make a good point regarding launch windows. The cost of moving an asteroid to cis-lunar space to increase access is very high, and may depend on the value of extracted material vs “slag”. I wonder if there is a sweet spot economically between delta-V and launch windows for mining drones.

      • Hop David September 24, 2016, 9:03

        Should momentum exchange tethers come into play, any source of up momentum could be valuable. And NEAs whose orbital energy is barely hyperbolic can be brought into high elliptical capture orbits with just a slight delta V budget. Some rocks can be parked in high lunar orbit for .17 km/s or even less.

        When it comes to anchor mass for tethers, silica works just as well as platinum. http://hopsblog-hop.blogspot.com/2015/05/orbital-momentum-as-commodity.html

    • Doug M. September 23, 2016, 10:42

      On the plus side, there are thousands of NEAs with semi-major axes between .95 and 1.05 AU. Even if you weed out the ones with significant inclinations, there’s always a launch window coming up to something.

      Doug M.

      • Hop David September 24, 2016, 8:45

        If we’re talking about an asteroid mine we need a supply line. Especiallly in the early stages when we’re establishing infrastructure and learning as we go. Since we have zero asteroid mining experience, early efforts will be a process of trial and error.

        So say we have a mine on asteroid A. Then a launch window opens for asteroid B. Is that any help for the mine on asteroid A? No. Yes, there’s a lot of different NEAs and launch windows open to different asteroids. But with a mine supply line launch windows to a single destination is what we’re concerned with.

  • Alex Tolley September 21, 2016, 17:47

    Didn’t Norad detect multiple kiloton atmosphere explosions on a very regular basis that were attributed to largish meteors? Minor planets are just at one end of the scale, with dust at the other, with a power law distribution (IIRC).

    Perhaps we should be concerned with the undetected objects, like the Chelyabinsk impact that caused considerable damage. While KT event sized impactors are extremely rare and unlikely to be of concern, more common objects that can do city center damage need to be tracked more effectively and means to destroy them developed purely as an economic issue. If an object wiped out a cultural city like Venice as depicted by Clarke in “Rendezvous with Rama”, the losses are more than economic.

    • ljk September 22, 2016, 9:53

      In Arthur C. Clarke’s 1992 novel The Hammer of God, about a large planetoid threatening to hit Earth and give everyone a very bad day, there was a part where they detonated a nuclear charge in space that left a “map” of where all the planetoids, comets, and meteoroids were in the Sol system, even and especially those which could not be easily seen otherwise.


      I don’t have the novel handy so I cannot remember the details, but I am wondering if such a method could actually work? I also recall the detonation seems to have created a matching response from an ETI.

  • Stan Erickson September 21, 2016, 19:13

    Does anybody have an estimate of what the mean time between impacts (on Earth) is as a function of size or mass? Is this curve going lower year by year with more discoveries?

  • James September 21, 2016, 21:34

    Anyway I can invest in Planetary or DSI

    • Paul Gilster September 22, 2016, 9:43

      Neither, as far as I know, is publicly traded at this point.

      • ljk September 22, 2016, 9:56

        When corporations finally wake up and realize just how much money there is to be made in space, then we will have our permanent presence in the Sol system at the least.

  • Eniac September 23, 2016, 8:25


    … as commercial operations use robotics and eventually humans to extract water and precious metals

    I am not sure that there is much reason to eventually use humans to extract water and precious metals if we already have robots doing it. Is there?

    The traditional miner is rapidly becoming a thing of the past here on Earth. I hardly expect the profession to be revived in space.

    • Hop David September 24, 2016, 8:51

      Robots sans humans are a way to get our foot in the door. But with light lag latency and low band width they are difficult to use. Also humans to maintain the robots are desirable.

      As soon as robots start extracting life support consumables and propellent, it will be much less expensive to bring humans on site. Human plus robotic teams are more able than either alone.

      I talk about that at http://hopsblog-hop.blogspot.com/2013/12/who-needs-humans.html

    • Paul Gilster September 24, 2016, 10:30

      Eniac, I would think that especially in the early going, humans are going to be needed for maintenance and repair of robotic systems that may eventually become capable of doing these things themselves.

  • ljk November 14, 2016, 12:08

    Rock Legends – the Asteroids and Their Discoverers

    Published: 10 November 2016

    by Mark Mortimer

    If we are indeed stardust, then what will our future hold? And what happened to all that other dust that isn’t in people or planets? These are pretty heady questions perhaps best left for late at night. Since the age of Galileo and perhaps even beforehand these inquisitive night goers have sought an understanding of “What’s out there?”

    Paul Murdin in his book “Rock Legends – the Asteroids and Their Discoverers” doesn’t answer the big questions directly but he does shed some capricious light upon what the night time reveals and what the future may hold.

    Full article here:


    To quote:

    Fortunately this book doesn’t just simply list discovery dates and characteristics. Rather, it includes significant amounts of its contents on the juicy human story that tags along, especially with the naming. It shows that originally these objects were considered special and refined and thus deserved naming with as much aplomb as the planets; i.e. using Greek and Roman deities. Then the number of discovered asteroids outpaced the knowledge of ancient lore, so astronomers began using the names of royalty, friends and eventually pets.

    Today with well over a million asteroids identified setting a name to an asteroid doesn’t quite have the same lustre, as the author is quick to point out with his own asteroid (128562) Murdin. Yet perhaps there’s not much else to do while waiting for a computer program to identify a few hundred more accumulations of dust, so naming some of the million nameless asteroids could happily fill in some time.

  • ljk December 5, 2016, 14:18

    Researchers discover tiniest and brightest near-earth asteroid

    2015 TC25 will likely never hit Earth, but researchers hope that studying it may lead to better understanding about asteroids that may one day be on a collision course with our planet.

    By Weston Williams, Staff

    December 4, 2016

    Full article here:


    The paper here:


  • ljk December 7, 2016, 12:16

    December 5, 2016 12:47 PM ET

    Quest to Reveal Asteroid’s Mysteries Before Japanese Spacecraft’s Visit


    The JAXA Hayabusa-2 mission will arrive at Asteroid Ryugu in 2018, but first astronomers need to study it from afar to understand what it’s made of long before the spacecraft attempts to touch down.

    Full article here:


  • ljk December 14, 2016, 9:26

    AIM misses the funding target, for now

    At a meeting of ministers of its member nations earlier this month, ESA got most of what it asked for, with the exception of funding for an asteroid mission called AIM. Jeff Foust recounts what happened to AIM and why ESA’s leader is not yet giving up on the mission.

    Monday, December 12, 2016


  • ljk December 21, 2016, 9:55