Dawn New Horizons

Pluto 2015

Vesta2011

Ceres2015

Waiting for their spaceships to come in…

…with help from Hubble in the meanwhile

Citation from IAU Minor Planet Circular 56612 on the naming of

Asteroid “6815 Mutchler”

Asteroids“ready for their close-up”

Max MutchlerHead, Research & Instrument Analysis Branch

Space Telescope Science InstitutePublic Lecture, 1 March 2011

Asteroids“ready for their close-up”

Max MutchlerHead, Research & Instrument Analysis Branch

Space Telescope Science InstitutePublic Lecture, 1 March 2011

“I’m ready for my close-up, Mr. DeVille”

"I am big, it's the pictures that got small!"- Gloria Swanson

“I’m ready for my close-up, Dawn”

"I am small, it's the pictures that got big!"- Asteroid Vesta

Asteroid history and mystery

• Ceres, Vesta, Pallas, discovered in early 1800s

• Called planets for 50 years, then re-classified: any déjà vu ?

• Key to understanding Solar System formation …and us

• Giveth: our oceans?• Taketh away: Killed the

dinosaurs? Still a threat?• Exploration with Hubble,

Dawn…and astronauts?

The largest Kuiper Belt Objects, and asteroids (or “protoplanets”)

Are they planets?

Ceres Vesta

Ceres

Asteroid Belt Kuiper Belt Discovered 1801-1851 Discovered in 1992

Ceres and Pluto: The “ugly duckling”problem of being the first of an entire class

Asteroids: typically rocky, with

circular orbits between Mars

and Jupiter…

…but there are someicy “Main Belt Comets”,and Near-Earth Objects

Main Asteroid Belt

Hubble images of Ceres reveal roundness, surface features, and colors

Hubble WFPC2 images of asteroid Vesta in May 2007: color composite movie

Hubble WFC3 images of asteroid Vesta in 2010: color composite movie

Dawn will spend several months in polar orbit around Vesta, before leaving for Ceres.

Over the last 16 years, Hubble observations have helped refine Vesta’s pole position, which can give Dawn extra time to do science, rather than making orbit adjustments.

A more accurate knowledge of the pole position will also help identify when the extreme latitudes will have the best possible solar illumination, and are “ready for their close-up” .

Improved Measurement of asteroid 4 Vesta’s rotational axis orientationJian-Yang Li,, Peter C. Thomas, Brian Carcich, Max J. Mutchler, Lucy A. McFadden, Christopher T. Russell, Stacy S. Weinstein-Weiss, Marc D. Rayman, Carol A. Raymond , 2010, Icarus

Dawn mission overview

• “Star Wars” ion propulsion allows for asteroid-hopping

• Launch 27 Sep 2007

• Mars boost 2009

• Orbit Vesta 2011-12

• Orbit Ceres 2015

• Pallas: can’t get there from here (anymore)

• Note: New Horizons Pluto flyby July 2015

So…why care about rocks in space?

We shall not cease from exploration and the end of all our exploring will be to arrive where we started and know the place for the first time.

-- T. S. Eliot

We see evidence of ongoing star formation in our own galaxy and other galaxies

These jets indicate a star forming inside this cloud

Our Sun forming from the collapse of a cloud of gas and dust, forms a rotating disk

Asteroids and comets are some of the best-preserved “fossils” from the early Solar System

Further collapse within the disk form the icy gas giant planets further out, beyond the “snow line”

The rocky terrestrial planets form closer in

There is evidence on Earth that planet formation involved violent collisions and impacts

Since the moon has no weather (erosion), the impact history is preserved much better

So we can surmise that the early Earth had no oceans, and was not hospitable to life

After the heaviest bombardment was over, later asteroid and comet impacts may have delivered water and organic material to Earth – the stuff of life

Water Ice Discovered on Asteroid for First Time By Clara MoskowitzSPACE.com Senior Writer28 April 2010

Water ice has been found on the surface of a nearby asteroid for the first time – a discovery that could help explain how Earth got its oceans.

Two teams of researchers independently verified that the asteroid 24 Themis – a large rock hurtling through space in the asteroid belt between Mars and Jupiter – is coated in a layer of frost. They also found that the asteroid contains organic material, including some molecules that might be ingredients for life.

The discovery might even provide clues about the origin of water on Earth. "Our data are certainly at least consistent with the idea that you could bring in plenty of water from impacts,“ said Andrew Rivkin of Johns Hopkins University.

Asteroid Scheila: a “Main Belt Comet”

In the wee hours of December 11th, University of Arizona astronomer Steve Larson was on cosmic patrol with the Catalina Sky Survey's Schmidt telescope. That's when he noticed something odd about the appearance of the main-belt asteroid 596 Scheila. The asteroid was clearly fuzzy, with a soft glow extending a few arcminutes to the west and north. Other astronomers quickly confirmed the cometary appearance. If Scheila is truly a long-dormant comet, then it's a big one: current estimates put its diameter at 70 miles (113 km).

"It's a main-belt comet, although I don't know what type yet," Dave Jewitt explains. He says it could have resulted from an impact (as occurred earlier this year with P/2010 A2) or outgassing (as occurs on 133P/Elst-Pizarro).

The Whole Shebang

The Earth (and life on it) has always been directly influenced by events in the larger universe…and always will be

Uh oh! You might want to pay more attention to those space rocks than we did !!!

Research by Dr. William F. Bottke, Dr. David Vokrouhlicky and Dr. David Nesvorny suggests that the impactor believed to have wiped out the dinosaurs and other life forms on Earth 65 million years ago can been traced back to a breakup event in the main asteroid belt.

The dinosaurs got a warning shot….

…before they met their fate

A main-belt comet?No, an asteroid collision…

“A recent disruption of the main-belt asteroid P/2010 A2”David Jewitt, Harold Weaver, Jessica Agarwal,Max Mutchler & Michal Drahus, Nature, Volume 467, 14 October 2010

Illustration by Anne Feild, STScI

• Earth-Moon formation

• Pluto and moons

• Vesta impact: created 50 smaller asteroids, 20% of meteorites… and any moons?

Big collisions in the early Solar System

Hubble reveals two new Pluto moons in 2005

Charon, Nix, and Hydra likely formed by collision…so Vesta should have moons too?

dwarf planet asteroid (small solar system body)

Hey, no fair!

But they are both “proto-planets”

Vesta’s impact crater,volcanic maria, dry?

Same initial conditions, but different subsequent evolutions

Thomas, P. et al., 2005, “Differentiation of the asteroid Ceres as revealed by its shape”, Nature Letters, Vol 437

Thomas, P. et al., 1997, “Impact excavation on asteroid 4 Vesta: Hubble Space Telescope results”, Science, Vol 277

So Vesta should have moons, right?

Satellite searchwith Hubble’s

WFPC2 camera,and with Dawn

as it approachesin July

Hill sphere(orbital stability zone)

Rosetta flyby of asteroid 21 Lutetia on 7 July 2010

An optical “ghost”… not a moon!

Hubble moon search for asteroid 21 Lutetia: a cautionary tale

Ongoing impacts and near-misses

Comet Shoemaker-Levy 9 impacts Jupiter in July 1994, shortly after the 1st Hubble servicing mission

What if Comet SL9 hit Earth instead of Jupiter?

Much less likely, but maybe we should try to understand these events?

Our fears (fueled by sci-fi)

This week’s New Yorker magazine

Fireball over Wisconsin on 14 April 2010: caused by an object only ~1 meter in diameter

About 100 tons per day impacts the Earth, in small pieces

The animation consists of 34 radar images of near-Earth asteroid 2010 JL33 taken by the Goldstone radio telescope on December 11 and 12, 2011. According to the JPL website, the radar observations reveal that "2010 JL33 is an irregular, elongated object roughly 1.8 kilometers wide that rotates once every nine hours."

To alter the orbit of a killer asteroid, we’d need to discover it decades before impact, not days

This kinda stuff takes serious time and money…

…gee, almost as much as a Hollywood movie budget!

Apophis

The 2029 “doomsday” asteroid you may have heard of

Near Earth Objects (NEOs) are ideal for

study and exploration

…as long as they don’t get too near!

Discovering NEOs….from space?

NASA's New Asteroid Mission Could Save the Planet By Tariq Malik SPACE.com Managing Editor16 April 2010

President Barack Obama set a lofty next goal this week for Americans in space: Visiting an asteroid by 2025. But reaching a space rock in a mere 15 years is a daunting mission, and one that might also carry the ultimate safety of the planet on its shoulders. "By 2025, we expect new spacecraft designed for long journeys to allow us to begin the first-ever crewed missions beyond the moon into deep space," Obama said. "We'll start we'll start by sending astronauts to an asteroid for the first time in history.“

Astrophysicist John Grunsfeld – a former NASA astronaut who three shuttle missions to fix the Hubble Space Telescope – suggested sending humans to purposely move an asteroid, to nudge the space rock to change its trajectory. Such a feat, he said, would show that humanity could deflect a space rock if one threatened to crash into the planet.

Scientists estimate there are about 100,000 asteroids and comets near Earth, but only about 20,000 are expected to pose any risk of impact. NASA has found about 7,000 of those objects, 1,000 of them flying in orbits that could potentially threaten the Earth in the future, NASA scientists have said. Astronomer Donald Yeomans, head of NASA's Near-Earth Object program office at NASA's Jet Propulsion Laboratory in Pasadena, Calif., said there are about a dozen near-Earth asteroids that could be within reach of manned spacecraft, but most of those are relatively small. To make a crewed mission worth it, the target space rock would likely have to be at least 300 feet (100 meters) wide. For comparison, the space rock that exploded in a magnificent fireball over Wisconsin this week was just 3 feet (1 meter) wide, Yeomans said.

But there are secrets locked away on asteroids that may hold the key to understanding the formation of the solar system. Asteroids are the thought to be the leftover remnants of the solar system's buildings blocks. The organic molecules and compounds on them may offer clues on how life began on Earth, and if it's possible elsewhere in the universe.

August 2, 2010

Apply Flexible Path to Near-Earth ObjectsDaniel R. Adamo

• Mandates to catalog NEOs in 1998 and 2005

• IR space telescope in Venus-like orbit to discover most NEOs

• 2010 Presidential endorsement for a mission in 2025 – but don’t pick a date!

• Asteroid within 0.1 AU > 50 m (only 3% of known), duration < 180 days, minimize delta-V (velocity changes)

• Asteroid 1999 AO10 example…try Space Game (citizen science)

• Precursor “scout” missions to characterize object, and manage potential hazards for astronauts:

• Mass, gravity field, spin: complicated orbit and approach?

• Moons or debris ring: spacecraft hazard?

• Volatiles beneath the surface (dormant comet)? No jets please!

Deep Impact / EPOXI flyby of Comet Hartley on Nov 4

Closest near-Earth comet in decades!

Robotic precursor missions needed to identify suitable NEOs for humans to visit

Hayabusa visits asteroid Itokawa

Asteroids and comets visited by spacecraft

Space Station compared to Comet Hartley 2

We don’t want to send astronauts to asteroids that might be dormant comets!

What might a human mission to a near-Earth asteroid

look like?

Illustration: IHMC

An “easy” 2025 destination:

Near-Earth asteroid 1999 AO10 “co-orbiting” with Earth

Profile of a 6-month mission to a near-Earth asteroid