# Presentation: 856535

## Stardust@home

**Dr. Bryan Méndez**Center for Science EducationUC Berkeley Space Sciences Laboratory

- Stardust@home is a UC Berkeley project funded by NASA

## Interstellar Dust

- The space between the stars is vast, but not empty. It is filled with gas and dust:
- The Interstellar Medium (ISM): stuff between the stars.

- The density of the Interstellar Medium is extremely low:
- 1 gas atom per cubic centimeter
- 1 dust particle per 1 cubic kilometer

- (one dust particle inside a volume equivalent to 250 football stadiums)

**Notes:**
To understand how low the density of the ISM is, consider that on Earth 1 cc of air contains 2.7x10^19 gas particles. 
IS dust is composed of microscopic particles of silicates, carbon, ice, and iron.
IS dust typical size is 0.1 microns 

## Interstellar Dust

**Interstellar Dust**

- Interstellar dust particles are created in many different environments:

- New stars and planets are formed from interstellar dust and gas.
**We are quite literally stardust!**

- Supernova Remnants

- Outflows from dying stars

- Atmospheres of Red Giant stars

## Interstellar Dust

- The Ulysses and Galileo spacecrafts detected a flow of interstellar dust through the Solar System coming from the direction of the constellation Ophiuchus

## Stardust Mission

- NASA’s Stardust mission launched in 1999 to collect dust from comet Wild 2 and return the samples to Earth.
- The first ever comet sample return mission.
- Science objective: to understand the materials and conditions that went into the formation of the Solar System.
- A very special material was used to collect the dust.

## Aerogel

**Aerogel**

## Stardust Mission

**Stardust Mission**

- Stardust made 3 orbits around the Sun to encounter Wild 2 and then returned home.
- Along the way, the aerogel collector was opened up into the interstellar dust stream to collect samples of dust coming from outside the Solar System.
- Stardust collected interstellar dust twice for a total of 6.5 months

## Stardust Mission

- Aerogel Collection Grid

- Sample
- Return
- Capsule

**Stardust Mission**

- Direction of Interstellar Dust

- The first time interstellar dust such as this was ever collected for return!

## Dust in the Aerogel

- With masses in the *pico*gram regime, the particles should only penetrate about 100 microns into the surface of the 3cm thick aerogel tiles, leaving behind tracks in the aerogel.

**Dust in the Aerogel**

- The particles are sub-micron in size and will be few in number, maybe 45 in the entire collector.
- The collector itself is about 1,000 cm2 in area.

**Notes:**
Picogram = trillionth of a gram

## Ants in a football field

- An automated microscope at JSC will scan through the grid taking digital “focus movies”. The field of view is about 0.5mm on a side. There will be over 1.6 million of these.
- Finding the interstellar dust particles will be like searching for 45 ants in a football field looking one 5cmx5cm square at a time.

## Finding the dust

- How do we find 45 microscopic particles somewhere within 1.6 million focus movies? The particles themselves are not visible in the movies, only the tracks they leave in the aerogel.
- We considered using pattern recognition software. But, because we have no knowledge of the condition of the aerogel until we look at it, nor do we really know what the particle tracks will look like, we would have to first teach the software to recognize particle tracks and differentiate them from other possible features. To do that we would need to *find* a dozen or so particles!
- People need to look through the movies.

## Stardust@home

- The task of manually searching through the 1.6 million focus movies would be overwhelming for a small research group...but not for an army of enthusiastic volunteers.
- The focus movies will be placed online for volunteers to examine.
- We estimate that it will take 30,000 person-hours to complete the task. We now have over 100,000 people pre-registered to participate.
- It will take several months for the automated microscope to complete the scan of the collector, that will be limiting time factor.

- http://stardustathome.ssl.berkeley.edu

## Virtual Microscope

- Volunteers will use a Virtual Microscope (VM) to examine focus movies.
- The VM will work directly within a web browser, no special software needed, simply an internet connection and a fair amount of RAM.
- A simple online training session and test will be required for volunteers to learn how to use the VM.
- The first focus movies will be made available online in April and the project will continue through November.

## How It Will Work

- Calibration movies will be placed into the data stream (movies known to have no particles, etc.) to gauge each volunteer’s sensitivity (find tracks when they are there) and specificity (find no tracks when they are absent). Each user receives an overall score.
- Each movie receives a score weighted by the score of the volunteer who flags it as either containing a track or not
- Scientists at UC Berkeley will follow up on all movies that receive a high enough score.

**How It Will Work**

**Notes:**
Minimum # of people: 4, Maximum: 10

## Recognition

- Website will feature a list of the volunteers with the top scores.
- Users achieving a high score will receive a certificate of participation.
- The first to find a track will have the privilege of naming the dust particle.
- Will also be given co-authorship of scientific papers about the discovery
- On average, a particle will be discovered every 4 days!

**Recognition**

## Educational Resources

- We will be developing lessons for students using the Virtual Microscope.
- We also provide professional development for educators about ISM, planetary system formation, and comets.

- Website will also contain educational materials developed by the Stardust mission E/PO team
- Will do professional development on these materials as well
- Stardust@home E/PO will last 3 years while the search will only last 6 months. E/PO will focus on the science, technology, engineering, and mathematics standards of the project.

**Notes:**
E/PO = Education and Public Outreach