The first object was spotted by the Lincoln Near-Earth Asteroid Research (LINEAR) sky survey. This project was set up by the United States Air Force, NASA and MIT’s Lincoln Laboratory with the aim of discovering and tracking near-Earth asteroids and it has had much success over the years. Observations are carried out by a pair of Ground Based Electro-Optical Deep Space Surveillance (GEODESS) telescopes which are located in Socorro, New Mexico. On January 6 the telescopes achieved their latest success when they observed a new object in the asteroid belt which is a region of the solar system located between the orbits of Mars and Jupiter. This new object was named P/2010 A2 and its appearance has caused some excitement in the astronomical community.

While it is not uncommon that a new object should be identified in the asteroid belt the unusual thing about P/2010 A2 is its appearance. Generally asteroids have a relatively circular orbit and are not volatile in nature. These show up as a speck of light on pictures taken from telescopes. Comets on the other hand tend to have an elliptical orbit around the Sun and exhibit a visible tail due to the effects of solar radiation on their nuclei. These tend to have a fuzzy appearance in pictures. The mystery with P2010 A2 is that it exhibits the traits of both an asteroid and a comet. While it has an orbit which is consistent with an asteroid the picture taken of the object appeared fuzzy which gives it the appearance of a comet. This came as a surprise in that comets do not normally reside in the asteroid belt and scientist have been working to come up with an explanation of why this should be.

Initial observations indicated that the aphelion (furthest distance from the Sun) of the object is only 2.6 Astronomical Units (AU). This would mean that it remains within the warmer inner regions of the asteroid belt where ice is less likely to form. The frost line is located at 2.7 AU and it is beyond this that more volatile ices are expected to form which are typical of a comet. With ice probably not forming on its surface, this has led to the theory that the unusual appearance may be as a result of a recent asteroid collision which exposed ice that had been originally trapped beneath the surface of the object. Melting of this ice and the resulting gas and dust which would be released would help to explain the tail of the object.

If this explanation is indeed true then it would be the first confirmed collision event between two asteroids. Although a similar event has probably occurred in the past, this would be the first time observations of the phenomenon had been made. Monitoring of the object is expected to continue in the near future to try and establish more details. Specialists hope that either the Hubble or Spitzer Space Telescopes can be brought to bear on the puzzle although this has yet to be confirmed.

In future another space telescope which may view the object is the WISE Telescope. This was launched into space at the end of 2009 and only a few weeks after the lens cover was removed from the instrument it is already starting to produce results. The official start of the WISE mission to map the entire night sky was January 14. However in tests prior to this the telescope showed why it will be an important part of detecting near-Earth asteroids in future. Two days before the official mission was to begin it was reported that WISE had already sighted its first asteroid. The sighting was confirmed by the University of Hawaii’s 2.2m visible light telescope and the asteroid was named 2010 SB78. Initial estimates indicate that the asteroid is around 1 kilometer in diameter and is currently at a distance of 158 million kilometers from Earth. It is not considered that the orbit of the asteroid will bring it near to Earth and while it is not considered to be a danger it will continue to be monitored.

With two new objects being discovered in a relatively short time period it is to be hoped that the pace at which asteroids are detected will accelerate in the future. The work of the many existing projects which detect and track near-Earth objects will be enhanced by the capabilities of the WISE telescope and this should mean our knowledge of asteroids in the vicinity of Earth should be greatly increased in the coming years.

WISE was launched on a Delta rocket on December 14, and after a few weeks of prepping the satellite, NASA jettisoned the cover that had kept the sensitive instrument cold. Since WISE sees in the infrared, it could pick up its own heat, which would ruin the data being collected. To guard against this, it was cooled with frozen hydrogen and sealed in a vacuum container similar in principal to a Thermos bottle. Now that it is in orbit and without its cover, the vacuum of space will serve the same purpose, but even better. At the moment, the instruments on the satellite are being calibrated, and observations will begin shortly. WISE will spend eighteen months surveying the sky, at which time it should have exhausted its supply of internal coolant. At that time, the mission will be over.

What are some of the things that WISE might find? Scientists have high expectations. This mission will build on the findings of two earlier infrared missions, COBE and IRAS. To get an idea of how big an improvement WISE is over its predecessors, consider this: while IRAS, which went up in the 1980′s, had only 62 pixels in its cameras, each of WISE’s four cameras has over a million. With eyes like that, it should be able to see a lot.

You can get an idea of the kind of science that will be done with WISE by considering the things it can see. The wavelengths that the satellite can detect fall into four bands:

Band 1: 3.4 microns- This is a broad filter to detect stars and galaxies.

Band 2: 4.6 microns- This is radiation from things that are too cool to be stars, but have some internal heat- in other words, brown dwarfs.

Band 3: 12 microns- This is the wavelength at which asteroids radiate in the infrared.

Band 4: 22 microns- At this wavelength, relatively cold things will be revealed, such as the dust of star-forming regions.

WISE will orbit Earth from pole to pole, surveying strips of the sky with each passage. This will allow each spot in the sky to be imaged many times, and by comparing the images, NASA scientists will be able to detect any that show visible movement over a short period of time. By doing, this, they will identify asteroids within the solar system, most of which are in the main asteroid belt between Mars and Jupiter. This will give us our first really accurate map of the asteroids in our system.

In addition to these nearer objects, WISE will be able to pick up the faint warmth of brown dwarfs. As stated above, these are bodies that are almost massive enough to become stars, but not quite. They never achieve nuclear fusion, the fundamental characteristic of stars, but they do emit some infrared radiation. It is possible that one or more brown dwarfs exist close to the solar system, but have remained undetected before now. WISE will find these objects, if they’re out there, and should even be able to pick up the glow from any planets that orbit them. (There is no reason why a brown dwarf should not have planets, though it is unclear whether they could support life.)

It is also hoped that WISE will show us the brightest galaxies in the universe. In addition to the faint objects that it will detect, the telescope will pick up infrared radiation from brighter sources, such as galaxies bursting with the heat of trillions of suns. These ultraluminous infrared galaxies, or ULIRGs, are almost undetectable in visible light surveys, and may not have been found before.

Other things that WISE is expected to see include young stars and the discs of planetary debris that surround them, clusters of galaxies in the distant, early universe, and a detailed view of our own Milky Way galaxy. In doing this, it will give the best view yet of the evolution of stars, protoplanetary discs, galaxies and clusters of galaxies- in other words, the universe from the bottom up.

The WISE mission promises to be a gold mine, providing enough data to keep the worthy scientists of NASA working for years. Unfortunately, we will have to wait a little while to see any results. The WISE data will be released in two stages. A preliminary release is scheduled to take place six months after the end of the mission, or about 16 months after launch, and a final release is scheduled for 17 months after mission’s end, or about 27 months after launch.

Watch for future articles about WISE at this website.

Sources:

WISE mission page at NASA website: wise.ssl.berkeley.edu/

Ten Things You Should Know About WISE at website of the Jet Propulsion Laboratory: jpl.nasa.gov/wise/facts.cfm

WISE Overview at website of the Jet Propulsion Laboratory: jpl.nasa.gov/wise/overview.cfm

WISE public website: astro.ucla.edu/~wright/WISE/

Lakdawalla, Emily: WISE Guys, at the Planetary Society Blog, August 27, 2009: planetary.org/blog/article/00002070/

The WISE Telescope is the latest in a long line of instruments that have been launched into space as part of NASA’s Explorer Missions. The instrument was designed, fabricated and tested by the Space Dynamics Laboratory in Logan, Utah and includes a 16 inch diameter telescope and four infrared detectors.

It has been launched into an orbit 525 kilometers above the Earth and will circle the planet 15 times a day, during which it will capture images of the night sky on an infrared sensitive digital camera. An image will be captured every 11 seconds with each picture covering an area of the sky around 3 times the size of the moon.

The operational phase of the mission is planned to last for 10 months and during the first 6 months of this the telescope will scan and map the entire night sky. Each position in the sky will be mapped at least eight times during this process and following its completion the telescope will begin a second scan which will continue for the remainder of the mission. The second scan will be used to try and identify further objects in the night sky and also to check if any changes have occurred since the first scan.

The mission has a number of objectives which include finding and studying asteroids and comets in our solar system, identifying the nearest and coolest stars which are know as brown dwarfs and to find the most luminous galaxies in the universe. It is expected that the mission will capture the images of hundreds of millions of objects in the night sky and the sensitivity of the infrared equipment is such that it will discover many objects that have previously gone unseen.
The finds that the telescope will make closest to our own planet will be near-Earth objects such as asteroids and comets which have orbits that bring them close to us. It is expected that hundreds of previously undetected dark asteroids will be identified by the mission and this will help in the search for potentially dangerous near-Earth objects which may be on a collision course with our planet.

The mission will also identify most of the asteroids with a size of 3 kilometers or greater in the main asteroid belt of our solar system and by measuring the infrared light from these will provide a good estimate of the size distribution of the asteroid population. Scientists should be able to use this information to make an estimation of how often it is likely that the Earth will have an encounter with a potentially dangerous object. The data collected should also provide an insight into the composition of asteroids and give clues as to whether they are solid or more like giant snowballs. Both the size and composition of an asteroid are important in determining its threat to our planet. The information from the mission will therefore assist future studies of potentially dangerous asteroids and also help in formulating a strategy for any that are found to be heading towards Earth and need to be dealt with.

The WISE Telescope will also be sensitive enough to identify brown dwarfs which form like stars but do not pick up enough mass to ignite nuclear fusion at their cores. It is suspected that around 1000 of these objects lie within 25 light years of planet Earth and the telescope should be able to provide confirmation of this. It has also been speculated that WISE may identify a ninth planet in our own solar system. The pattern of comet orbits around the Sun suggest that there may be a giant gas planet on the outskirts of our solar system about 25,000 times as far from the Sun as planet Earth and if this is the case then WISE should be able to confirm its existence.

Other finds are expected to include millions of energetic galaxies which are known as ultra-luminous infrared galaxies, newborn stars and disks of planetary debris around young stars. The most interesting finds that the WISE Telescope makes will be followed up by other missions including the Hubble Space Telescope, the Spitzer Space Telescope and ground based observatories. Information from the mission will also be used to target interesting areas of the universe by the James Webb Space Telescope when it is launched in 2014.

Data from the mission will be released in two stages. A preliminary release is scheduled for 6 months after completion of the mission and the final release will follow on 11 months after this. The results will be eagerly awaited by the scientific community and hopefully the mission will be a stunning success, providing new and exciting information that will broaden our knowledge of the solar system and universe in which we live.