NASA explores the solar system through remnants on Comets

On November 4, 2010, NASA's EPOXI spacecraft, about 450 miles from Comet Hartley 2. This is a small Comet with a diameter of less than a mile, and needs about six and a half years to orbit the sun. Comet is officially called 103P / Hartley 2 , this is the 5th Comet that scientists have collected close-up images.

On September 30, 2010, the amount of hydrogen increased by 2.5 times a day.Look at the hydrogen clouds around Comet.Comet and the size of the cloud is quite small.

However this Comet was observed from the SOHO spacecraft, known for its remarkable performance in observing the sun. Together, both spacecraft will return to Earth data on what is unusual on Hartley Comet 2, ice blocks that burst out and evaporate quickly at a surprising speed.

" By combining analysis of images taken directly by the EPOXI spacecraft and the data collected for several months by the SOHO spacecraft, we had a rare opportunity to see Hartley Comet. 2 in the process of releasing a significant amount of water, "said Michael Combi, a space scientist, working at the University of Michigan, at Ann Arbor, Michigan, USA.

The results of this study were published in the Astrophysical Journal Letters , issue June 10, 2011.

"Comets are always dehydrated when they are warmed by sun exposure , but this is quite impressive, there are many unusual and happening for weeks. "

The need to understand the composition and behavior of Comet Hartley 2 has prompted scientists to continue their work because Comet Hartley 2 is one of the first objects to form around the solar system of we were about 4.5 billion years ago and they have grown little since then. Frozen blocks of ice, ice and air block keep clues about what existed in the early days of the solar system. Therefore, Professor Michael Combi used a SOHO ship tool called SWAN - using anisotropic energy of the solar wind to observe the waterways of Comet.

The main work of SWAN is to map the distribution of hydrogen atoms across the entire sky. This helps those who study the solar magnetic environment, tracking the magnetic winds that contain particles moving through the space between the planets. But the SWAN device can also help track Comet Hartley 2, which is generally surrounded by extremely thin vapor-containing air. Under ultraviolet light from the sun, hydrogen atoms fly away from the water molecule at great speed and create a hydrogen cloud. The sunlight absorbs this cloud and then returns it, making the cloud cloud identifiable by the SWAN device. Observing the hydrogen cloud will help determine how much water is evaporating from Comet over time.

SWAN has collected data of nearly 100 Comets, so Combi and his colleagues at the University of Michigan, USA, have planned ahead to have access to Sao's high-resolution images. broom Hartley 2. Researchers have a better understanding of the old Comet Hartley 2 data from 1997 until 2004. Unfortunately, the vision of SOHO is shrouded in sunshine in 2004, but the data in 1997 can be used for research. They compare these data with the data collected by SWAN tool between September 14 and December 15, 2010.

Surprisingly, the melting process of Comet Hartley 2 in 1997, produced three times the amount of water in 2010. " We analyzed many Comets with repetitive cycles in orbit. around the sun for a short time like Comet Hartley 2 above, '" Combi said . "But none of these Comets show such a dramatic change from one cycle to another across the sun."

The data that the SWAN tool obtained shows another surprise. On September 30, 2010, the amount of hydrogen increased by 2.5 times a day, and then halved again in about six weeks.

The standard model of how comets work helped the Combi team confirm the correlation of the amount of hydrogen generated, with the amount of water being removed from the surface of the Comet, the process called ' sublimation , 'because water directly changes from ice to gas without going through the liquid phase. The amount of surface area predicted did not go hand in hand with the data obtained from the EPOXI spacecraft, what we see is a Comet whose water forms half of its shape. But the EPOXI spacecraft also captured the image of an expanding halo of ice fragments of Comet, most likely thrown into space by CO ₂ emissions on the surface of Comet Hartley 2. These Ice blocks have freed more water, making hydrogen clouds sublimated.

" The much higher rate of water generated in 1997 implies that ice fragments are even more serious then ," said Joe Gurman, solar physicist and project scientist for the ship. SOHO universe at NASA's Goddard Space Center in Greenbelt, Md, USA. " For me, this means we are watching Comet Hartley 2 being 'dried up' and become less active inside the solar system ."

Data of the spacecraft EPOXI always go hand in hand with the current understanding of Comet. EPOXI measures cyanide output - a factor that tends to be quite small in Comet, but it's very bright, easy to measure and actually one of the first elements identified in Hartley 2. Cyanide output usually related to water production, but in this case EPOXI saw cyanide boom - up 7 times on September 17, 2010 - at a time when water only increased slightly.

Analysis of all this data on Hartley 2 has just begun, Combi said, " So it will take some time before we discover all that is happening. This is another Comet. We don't know if this is a single act or of some kind of Comet that has a different composition - but maybe we'll start to see things like this, even if it's late Other Comets. "

Spacecraft only approaches 5 Comets at close range, new data can help increase our understanding of Comet's composition. Comets are still an interesting scientific debate, because unusual Comets like Hartley 2 will have different expressions, because they were originally formed from different materials or because They have experienced different environmental conditions over time. When analyzing the data of the EPOXI spacecraft and future SWAN instruments will provide insight into the remnants from the early days of solar system formation.