The Akamai Observatory Short Course

Science and Engineering Activity

Thursday June 7, 2007 1:00 – 5:30 p.m.

Action Items:

Learn Stuff and Get resources (e.g. ppt slides)

• Hayabusa or other asteroid rendezvous mission = David
• Deep Impact, Hayabusa = Steve (from K.Meech and D.Tholen)
• Deflection/Detonation Scearios = Scott (watch Armageddon?)
• Design the object = Steve (w/help from IfA^? small bodies group)
• Refine the activity structure and timeline = Rich

Goals:

Students gain an understanding of the direct relationship between science and engineering.

This relationship includes a number of components. One is how engineering constraints can dictate what science is accomplished, and the inverse of that, how technology can also enable science discoveries. There is also a flow down (and up) relationship of how science requirements affect the engineering design. Research and development, which is somewhere in between pure science and applied engineering is also a factor in what tools are available to do science.

• See the time line, content and desired outcome for the activity: SE_Matrix_Time0529.doc

People

Lead Moderator: Rich Matsuda (lead EE group) Support: Steve Rodney (UH IfA^?), Scott Seagroves (UCOLick)

Collect a panel of Keck employees from different disciplines:

• Al Honey (Software E);
• Kenny Grace (EE); TBC
• Jim Bell (ME/Optics);
• David Le Mignant (Inst. Scient.); (If needed)

1. Intro: The end of the world as we know it

• It is the year 2010. The newly operational Pan-STARRS telescope discovers an object from the outer solar system with a high probability of impacting the earth in 2043.
• Students must design a science mission (ground-based or space-based) to learn enough about the object to determine the best way to deflect it.
• AND Students must design a mission to get to the object and deflect it.

Intro presentation by Steve and Scott? Present the problem, basic background on asteroids and comets, quick examples of previous missions (Hayabusa, Deep Impact), time constraints. Lay out the activity for them.

• science_intro.ppt: steve's science introduction, final version
• Suggestion for an asteroid name: Moros

2. Questions

moderator: Rich

• Student brainstorming about the scientific questions. Sort out questions and select a few of them to continue. Examples of the type of questions we're looking for: Is it a comet or an asteroid? How big is it? How dense is it? What is the probability of impact?
• More brainstorming on ways to deflect the (still mysterious) object. Examples: grav. tractor, solar sail, nukes. Questions: When do we have to launch to reach it? How much time do we need to deflect it?

• Either by consensus or a vote decide on:
  • the (five) most important things that we need to learn about the object.
  • the general pre-design of the deflection mission

3. Subgroups

(At this point, we could give them a little more info about the object. e.g. New observations have come in that indicate it is a comet, not an asteroid, and we have a rough albedo measurement and a refined trajectory. This would allow the groups to hone in on specific important questions with some broad mission design constraints)

Break out into subgroups of 3-4 students per group. Example groups:

• Group A: quantifying the threat (how will we learn about the object)
• Group B: getting there (how will we get our payload to the object)
• Group C: deflecting it (what will we do to change its trajectory)

• moderators will encourage asking both science and engineering questions, and lots of communication between groups,
• content is important but the most important is the process: project development (pre-design, design, requirements, scientific & engineering disciplines involved)
• Additional considerations to prompt: Cost estimates, risk assessment, redundancy, fall-back plans

4. Plenary Session

One representative from each group reports back to the plenary group in a mock Preliminary Design Review and identify the most challenging parts of the project (basically engineering vs R&D and how this affects the science path).

Reports is oral with possibly sketches and summary on poster.

The panel is here to guide and ask rigorous questions, help for the synthesis of the design and make it a rich and flavorful discussion.

Finally, give a pass or a no pass for the project to continue.

Resource and bibliography:

• From scientific publications :
  • June 2006 special issue on Hayabusa and (killer) asteroids in online Science Mag.
  • Jones et al. 2002, "The Next Giant Leap: Human Exploration and Utilization of Near-Earth Objects", PASP, ADS link
  • Mueller at al 2005, "Thermal infrared observations of the Hayabusa spacecraft target asteroid 25143 Itokawa" (using ground-based telescope in the N and Q band) link
  • Fargion et al. 1998, "Breaking and splitting asteroids by nuclear explosions to propel and deflect their trajectories" astro-ph abstract
  • UCSC's Erik Asphaug writes in Science to comment on Miyamoto et al: "Are any asteroids monolithic? And if not, what happens when we try to push on one in earnest, as may be required to divert a hazardous asteroid or to corral a resource-rich one into a beneficial orbit?"
• From the Planetary Society:
  • Apophis Mission Design Competition
  • Hayabusa MIssion to Itokawa
• Other links:
  • Impact effect calculation page
  • From F. Marchis lecture on introduction to astronomy (DLM uses it with permission from the author):
    • Comets - ppt
    • Asteroids 1 - ppt
    • Asteroids 2 - ppt

• On deflection strategies:
  • There are a couple different classes of deflection strategies -- basically those that impact or do some kind of sudden impulse, and those that act more slowly. From the March 2007 NASA NEO report to Congress, summary tables of the two main types of strategies (on these tables, "PHO"="potentially hazardous object"):

• • • Of the two kinds of strategies, nuking an object definitely offers the most transfer of momentum. The report concludes that nuclear "standoff" explosions are probably the most effective. Actually blowing up a nuke under the surface transfers more momentum, but the nuclear standoff explosion runs the least risk of fracturing the object. Here's a graphic stolen from a space.com article: Standoff explosions slow the object down by vaporizing one side of the object -- the vaporized particles impart a recoil onto the object. However, the report warns that nuclear strategies are risky to develop and operate, and all have some potential to fracture the object (which doesn't help anything).
    • Any explosive or impacting strategy might fail if the object is a rubble pile, a loosely gravitating ball of individual rocks. A rubble pile has internal degrees of freedom -- it can dissipate energy by just absorbing it. You can deflect a solid rock much easier than you can deflect, say, a giant loosely-held-together sandbag. Again, of all the explosive strategies, the nuclear standoff seems to be the best option even for the rubble pile. I think that's because the "vaporization" pushes on many points of the rubble pile simultaneously. (As opposed to, say, hitting it with a gigantic massive bullet to change its momentum.)
    • The other class of deflection strategies, "slow push" strategies, are really neat ideas but don't impart nearly the momentum shift of the explosive/kinetic strategies. Still, they tend to be safer to develop, safer to operate, and some might work even on a rubble pile. However, they need long lead times both because they act slowly and because they are the least technically developed right now.
  • Resources:
    • NASA Near Earth Object program page including March 2007 report to Congress, get the full report in PDF here
    • To Nuke or To Nudge? on space.com
    • Asteroid Deflection Strategies on the Wikipedia
    • The B612 Foundation An organization that is playing out our scenario in real life.
    • Nature paper co-authored by UH Alum and astronaut Ed Lu, on using a "gravity tractor" to tow an asteroid off its collision course. astro-ph

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