Asteroid of the Half-Month: 25143 Itokawa Part III

Of all the challenges found by the new Hayabusa space probe (and there were lots), none involved lugging giant instruments around the Solar System. The entire craft weighed just over 500 kg, and a quarter of that was propellants. Scientifically, the investigations aboard Hayabusa were sufficient, not bleeding-edge. Things like high-resolution telescopes were left on Earth, as they should. Instead, particles of 25143 Itokawa were taken to our giant instruments- a sample return mission. Such were the open questions left by the Galileo mission, NEAR, etc.

Hayabusa did not visit 4660 Nereus as first planned. That would have been nice, but a C-type body was left to Hayabusa 2. Itokawa is, rather, an S-type; a sample would settle the issue of ordinary chondrite meteorites and S-types in a way that Galileo and NEAR only inferred. We see lots of S-type asteroids in our telescopes- they’re the number one type in the inner Solar System. And we have plenty of ordinary chondrites that fall to Earth- again, they’re the most common. Yet S-types don’t look like OCs, but like stony-iron meteorites.

Itokawa flew past Earth in 2001. Telescopes around the globe got observing runs, if for no other reason to lower risks for Hayabusa operations. Jun 2004, as Hayabusa was in flight, Itokawa made its next Earth pass. It came within two million km, under half its 2001 range. This was part of the logic for Itokawa: an easy target, with a favorable, Earth-crossing orbit (“low ΔV”). Even if Hayabusa failed, mustering the astronomy world was an achievement.

Hayabusa did not fail, but got over 1500 particles from a known body. The craft’s (lightweight) instruments also rendered data (and knowledge) of the sampling site. We know how our samples fit into contexts- of Itokawa as one example of asteroid diversity, and the site as one example over Itokawa’s surface. Not some random outlier, from some random body.

Ground telescopes, flight probes, and sample examination combine in complementary ways. Let’s look at not just a space body, but the investigation process: Solar System science.

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Asteroid of the Half-Month: 25143 Itokawa Part II

Soichiro Honda (yes, that Honda) once got asked the secret of his success. He reportedly said ‘One word: lucky.’ During the rise of Honda and similar manufacturers, Japan was dismissed as a land of cheap knockoffs. That era is clearly done. Japan has done the world’s first asteroid sample return, Hayabusa, though luck (good and bad) was clearly part of its story.

Japan has long wanted asteroid materials. In Jun 1985, nearly two decades before the launch of Hayabusa, a sample return meeting1 was gathered. This itself was after NASA and the NSF led an oversubscribed, 1971 international conference2 on asteroid exploration. In that and the following years, Peak Oil and the embargos added even more urgency if not funding. Through Hayabusa, we found something even more enabling: water in space.

Quick recap: the Hayabusa mission launched in May 2003, reached asteroid 25143 Itokawa, and gathered a sample. It returned in Jun 2010, dropping a reentry pack.

But back to 1985. That year, a Japanese team was assembled to analyze sample returns. They devised a mission to 1943 Anteros and back. Its trajectory was “surprisingly but accidentally very closely identical to the orbit of Hayabusa.” However, given 1985 technology (like chemical rockets) the mission was far too big and heavy (Kawaguchi et al. 2006). But by 1994, the Clementine probe had tested miniaturization, in flight. Crude forms of electric propulsion were flying, and ion thrusters were about to (gradually) take over communications satellites (such as Japan’s own ETS-6). Before Clementine even disbanded, a new Japanese team had formed, to study electric rockets for Mars and Near-Earth Objects (NEOs). They moved fast (for space), publishing a paper the next year on electric-thrust sample return (Kawaguchi et al. 1995). That mission got approved by Apr 1996, the start of Japan’s next fiscal year.

You may be thinking ‘April 1996 approval to May 2003 launch? What took seven years?’

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AotHM: 25143 Itokawa Part I

If you’re reading this- in English, off the internet- odds are good you’re not Buddhist. But you are a driver, or you trust car owners. Drivers are in your community, your circle of friends, workplace, likely your household. And you’re all certainly eaters. We can thank the Japanese (later Taiwanese, Koreans, etc.) for cars and consumer electronics. Yet not large-scale rockets, airliners, and similar aerospace pursuits. Why not? What’s the difference?

We (as in Western, educated, industrialized, rich democracies) hold positive images of ‘Japanese things’. That phrase, for a long stretch of time, conjured thoughts of your Sony stereo, the Honda in the driveway (and not in the shop), maybe the Lexus you wish was in the driveway. In this same period, the Japanese image of ‘Made in America’ was of substandard quality, possibly including the Space Shuttle blowing up. And that Americans are fat. They do buy tickets to Hollywood blockbuster productions, though, and ride Boeing airliners if not Chevy pickups. Tacitly, Japan’s space efforts are substandard. Again, why?

Like most nations, Japan started with sounding rockets- small, suborbital launchers for atmospheric studies, the aurora and ionosphere, etc. Since these are smaller, cheaper vehicles, they’re appropriate and accessible to learn rocketry and space hardware and operations. (This is where Brazil is now.) They also resemble tactical missiles- the short-range weapons most armies, navies, etc. buy, which makes production rates high. Japan’s sounding rockets include the Lambda series. As in Western practice, Greek is built into academia and science.

If one tries larger and larger rocket classes, though, the curve doesn’t just taper off, it breaks…

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Retreat. Abandonment. Misleadership.

I had spoken- firsthand- with an extremely high-ranking government official. The United States has no plans (i.e., no funds) for a human Mars mission. ‘Back To The Moon’ is a fig leaf.

We are now seeing the fig leaf publically, though there had been flashes for about a year now, plus precedent. A dog and pony show is being made of what should be a simple fetch trick. This is, quite possibly, a ruse put on the electorate, and at best, incompetence at the highest levels.

Instead of a crewed Mars program, the Earth’s moon is being put forward, both as a human mission target in its own right, and as a programmatic step on the way to Mars. This is a sham; Earth’s moon is not a steppingstone on the path, but an opportunity cost and therefore a step away. The opportunity cost is surprisingly high, and the steppingstone value that has been touted does not hold up to scrutiny. Some aerospace organizations and contractors were aware of this, some are now complicit, and some are quietly hedging the problem. If you aren’t grasping the problem right now, just look to 2007, when the Bush sham had collapsed.

NASA’s yearly budget stands at less than 1 percent of the US federal budget. In the ’60s, the Apollo program made it peak at fourteen percent of the budget. That is, the civil government line item, spacewise, is not lower by a margin, not lower by a multiple, but by a logarithm. All talk of a NASA funding increase by the Trump administration is, in effect, talk. Such an increase for FY18 was not logarithmic, or a multiplier, but barely keeping pace with inflation. In other words, it wasn’t a real increase, in both senses of the term. Instead, the Trump White House expects NASA to fund itself by shedding projects- that is, cannibalization. If you aren’t grasping the ploy and its failings, just look to 2005, because it’s exactly what the Bush White House tried.

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AotHM: 87 Sylvia

If there’s a touchstone asteroid, this is it: 87 Sylvia invokes everything posted on this site, from asteroid spectral signatures, to asteroid moons, collisional families and other orbital dynamics, organic chemicals in space, asteroidal water ice, and gravity/tide effects. Sylvia also happens to be the eighth largest asteroid by size, at ~380 km long and somewhat less in width.

Going by telescopes alone, Sylvia was a dot. Still, we can study the spectra (color signatures) to classify bodies by surface material. Asteroids usually split into S-type (rocky, plus some metallic character) and C-type (rock, with carbon compounds). Oddballs fell into “X” or “U” (Unknown) classes, before we subdivided those into better categories. There are transitional objects too, not neatly pigeonholed; they may get two letters. Sylvia, at various times, has been called an X, U, or C asteroid, until the P-type emerged as a subtype of X. In the ’70s, one poor scientist simply listed it as “CMEU”- being on the safe side, perhaps. In any case, Sylvia isn’t rock and metal; P-types are primitive, made of stuff little changed in billions of years.

In orbital terms, Sylvia is in the outer Belt. Way out- the Cybele group (named for asteroid 65 Cybele) is a population of objects we take to be the Belt’s edge. (Fuzzy as that may be.) In the Cybeles, Sylvia is in a collisional family, the Sylvias. Asteroid families are assumed to be fragments split from their largest member, or maybe a parent body that was destroyed in the family-forming impact. Other large bodies in the Sylvia family include 107 Camilla; the Sylvias themselves may be related to the other Cybeles somehow.

Sylvia was then found to have a moon- two, in fact, a triple asteroid. With adaptive optics (AO), the shimmer of the atmosphere can be reduced. Large telescopes, aided by AO, can reach stunning resolutions. As AO developed in the late ’90s, we began spotting not only asteroid shapes but asteroid moons. 45 Eugenia had Petit-Prince; then in 2001, we found Romulus orbiting Sylvia. In 2004, Remus was also seen; rechecking Eugenia found Princesse. These moons act as gravity gauges; the moons of Sylvia tell us Sylvia is… a giant comet.

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AotHM: 1620 Geographos II

1620 Geographos was a special place in space history, figuratively and literally. It was targeted by 1994’s Clementine, the first deep space probe of the modern era. Physically, it was one of the first PHAs (Potentially Hazardous Asteroids), uncomfortably close to us, and exploitably close. By 1994 it had been eyed for 24 years- the Manifest Destiny of space past Apollo.

Where Eros is an Earth-approacher, Geographos is an Earth crosser- it actually passes inside us, and most of the way to Venus at one point in its orbit. Debris from Geographos, it is claimed, creates one to possibly multiple meteor showers. This close orbit is “linked”- not an accident or coincidence, but likely altered by some previous Earth pass. Our gravity had pulled Geographos into its current state. One proposal (Herrick 1979) was not just for exploration but infrastructure- we would finish the job, send Geographos (whole or part) into Earth, and dig a second Panama Canal. Afterward, the asteroid material would be a shallow metal mine.

Neither Eros nor Geographos got visited by post-Apollo programs. The billions wasted on Vietnam and the Space Shuttle weren’t policy, but palpable. 24 years later, Geographos would finally get a launch, via a refurbished Titan missile, designed before Vietnam. Its payload, Clementine, represented new thinking and developments, post-Shuttle.

Galileo, a late-70s design, had first mover advantage, exploring 951 Gaspra in a flyby. But Clementine would study the first Near-Earth Object (NEO), versus Gaspra in the Main Belt. Are planet-crossers different? They’re certainly warmer. Did they have similar formations, and later alterations? NEOs are on average smaller. Is there a size effect? Gaspra had regolith, a “soil” of rock particles. Do NEOs have it as well, are they too small to form it, or is it lost somehow? And where do Mars’ moons Phobos and Deimos fit in? The DoD, NASA, and industry had all agreed “a mission to a near-earth-asteroid was desirable and feasible from both organizations’ standpoint” and on the “obvious scientific value of an asteroid flyby” (Nozette 1995)

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Asteroid of the Half-Month: 1620 Geographos I

The 1980s can be thought of as the decade when asteroid studies (and to an extent comets) broke open. The Palomar-Leiden program had found lots of new targets, using photographic plates; the promise of digital sensitivities (via the new CCD detectors) meant lots more on the way. The Pioneers and Voyagers had reached Jupiter, Saturn, and Uranus, after Viking had orbited Mars; small moons in these systems whetted the appetites for asteroids. A dust disk had been found around the star Beta Pictoris; if other stars had disks of material, some of those disks were forming asteroids, comets, and eventually planets. In 1986, it was found that an asteroid had made a close brush past Earth; this was only found afterward, while it was receding again. And this is all after the Alvarezes not only found an explanation for the end of the dinosaurs, but found an asteroid crater in Mexico that would explain it.

Asteroid 1620 Geographos was being studied before all of this. It was under consideration in 1970, while the Apollo astronauts were picking up rocks. Consideration for mankind’s next leap, past Earth’s moon. Consideration by some of the top scientists of the day.

The 1980s can also be thought of as the decade NASA ground to a crawl under its own bulk. The Shuttle was finally flying, years behind schedule and about US$1 billion over budget. Galileo, tied to Shuttle, was thus not flying; Hubble didn’t even see the ’80s at all. No Halley probe flew, as NASA was left on the ground by the other space powers. Instead, CRAF (Comet Rendezvous/Asteroid Flyby) got offered as Cassini’s offshoot (“Mariner Mk. II”), before it too got the ax. After the Challenger disaster, Reagan, rather than deliver a coup de grace, threw another log on the flames (we’ll get back to this). NASA was now mandated with a space station (which couldn’t possibly fly in Reagan’s term). This mandate would go on to threaten Cassini.

The ’90s, then, was the decade asteroids were actually considered- i. e., with a budget line, resulting in actual hardware. That budget was military, not NASA; that asteroid, Geographos.

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