Featured Research

from universities, journals, and other organizations

Rosetta takes comet’s temperature

Date:
August 1, 2014
Source:
European Space Agency
Summary:
ESA's Rosetta spacecraft has made its first temperature measurements of its target comet, finding that it is too hot to be covered in ice and must instead have a dark, dusty crust.

The first temperature measurements of comet 67P/Churyumov–Gerasimenko were made between 13 and 21 July, when Rosetta closed in from 14 000 km to the comet to just over 5000 km. The observations were made by the spacecraft’s visible, infrared and thermal imaging spectrometer, VIRTIS, and revealed an average surface temperature of –70ΊC. This implies the surface is predominantly covered in dust rather than ice, which would yield a lower temperature. The finding does not exclude localised patches of ice. The observations were made when the comet was roughly 555 million kilometres from the Sun.
Credit: ESA

ESA's Rosetta spacecraft has made its first temperature measurements of its target comet, finding that it is too hot to be covered in ice and must instead have a dark, dusty crust.

The observations of comet 67P/Churyumov-Gerasimenko were made by Rosetta's visible, infrared and thermal imaging spectrometer, VIRTIS, between 13 and 21 July, when Rosetta closed in from 14,000 km to the comet to just over 5000 km.

At these distances, the comet covered only a few pixels in the field of view and so it was not possible to determine the temperatures of individual features. But, using the sensor to collect infrared light emitted by the whole comet, scientists determined that its average surface temperature is about -70ΊC.

The comet was roughly 555 million kilometres from the Sun at the time -- more than three times further away than Earth, meaning that sunlight is only about a tenth as bright.

Although -70ΊC may seem rather cold, importantly, it is some 20-30ΊC warmer than predicted for a comet at that distance covered exclusively in ice.

"This result is very interesting, since it gives us the first clues on the composition and physical properties of the comet's surface," says VIRTIS principal investigator Fabrizio Capaccioni from INAF-IAPS, Rome, Italy.

Indeed, other comets such as 1P/Halley are known to have very dark surfaces owing to a covering of dust, and Rosetta's comet was already known to have a low reflectance from ground-based observations, excluding an entirely 'clean' icy surface.

The temperature measurements provide direct confirmation that much of the surface must be dusty, because darker material heats up and emits heat more readily than ice when it is exposed to sunlight.

"This doesn't exclude the presence of patches of relatively clean ice, however, and very soon, VIRTIS will be able to start generating maps showing the temperature of individual features," adds Dr Capaccioni.

In addition to global measurements, the sensor will study the variation of the daily surface temperature of specific areas of the comet, in order to understand how quickly the surface reacts to solar illumination.

In turn, this will provide insight into the thermal conductivity, density and porosity of the top tens of centimetres of the surface. This information will be important in selecting a target site for Rosetta's lander, Philae.

It will also measure the changes in temperature as the comet flies closer to the Sun along its orbit, providing substantially more heating of the surface.

"Combined with observations from the other 10 science experiments on Rosetta and those on the lander, VIRTIS will provide a thorough description of the surface physical properties and the gases in the comet's coma, watching as conditions change on a daily basis and as the comet loops around the Sun over the course of the next year," says Matt Taylor, ESA's Rosetta project scientist.

"With only a few days until we arrive at just 100 km distance from the comet, we are excited to start analysing this fascinating little world in more and more detail."

More about Rosetta

Rosetta is an ESA mission with contributions from its member states and NASA. Rosetta's Philae lander is provided by a consortium led by DLR, MPS, CNES and ASI. Rosetta will be the first mission in history to rendezvous with a comet, escort it as it orbits the Sun, and deploy a lander.

Comets are time capsules containing primitive material left over from the epoch when the Sun and its planets formed. By studying the gas, dust and structure of the nucleus and organic materials associated with the comet, via both remote and in-situ observations, the Rosetta mission should become the key to unlocking the history and evolution of our Solar System, as well as answering questions regarding the origin of Earth's water and perhaps even life.


Story Source:

The above story is based on materials provided by European Space Agency. Note: Materials may be edited for content and length.


Cite This Page:

European Space Agency. "Rosetta takes comet’s temperature." ScienceDaily. ScienceDaily, 1 August 2014. <www.sciencedaily.com/releases/2014/08/140801111111.htm>.
European Space Agency. (2014, August 1). Rosetta takes comet’s temperature. ScienceDaily. Retrieved September 19, 2014 from www.sciencedaily.com/releases/2014/08/140801111111.htm
European Space Agency. "Rosetta takes comet’s temperature." ScienceDaily. www.sciencedaily.com/releases/2014/08/140801111111.htm (accessed September 19, 2014).

Share This



More Space & Time News

Friday, September 19, 2014

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

Boeing, SpaceX to Send Astronauts to Space Station

Boeing, SpaceX to Send Astronauts to Space Station

AFP (Sep. 17, 2014) — NASA selected Boeing and SpaceX on Tuesday to build America's next spacecraft to carry astronauts to the International Space Station (ISS) by 2017, opening the way to a new chapter in human spaceflight. Duration: 01:13 Video provided by AFP
Powered by NewsLook.com
East Coast Treated To Rare Meteor Sighting

East Coast Treated To Rare Meteor Sighting

Newsy (Sep. 16, 2014) — Numerous residents along the East Coast reported seeing a bright meteor flash through the sky Sunday night. Video provided by Newsy
Powered by NewsLook.com
Space Race Pits Bezos Vs Musk

Space Race Pits Bezos Vs Musk

Reuters - Business Video Online (Sep. 16, 2014) — Amazon CEO Jeff Bezos' startup will team up with Boeing and Lockheed to develop rocket engines as Elon Musk races to have his rockets certified. Fred Katayama reports. Video provided by Reuters
Powered by NewsLook.com
NASA Picks Boeing and SpaceX to Ferry Astronauts

NASA Picks Boeing and SpaceX to Ferry Astronauts

AP (Sep. 16, 2014) — NASA is a giant step closer to launching Americans again from U.S. soil. It has announced it has picked Boeing and SpaceX to transport astronauts to the International Space Station in the next few years. (Sept. 16) Video provided by AP
Powered by NewsLook.com

Search ScienceDaily

Number of stories in archives: 140,361

Find with keyword(s):
 
Enter a keyword or phrase to search ScienceDaily for related topics and research stories.

Save/Print:
Share:  

Breaking News:
from the past week

In Other News

... from NewsDaily.com

Science News

Health News

Environment News

Technology News



Save/Print:
Share:  

Free Subscriptions


Get the latest science news with ScienceDaily's free email newsletters, updated daily and weekly. Or view hourly updated newsfeeds in your RSS reader:

Get Social & Mobile


Keep up to date with the latest news from ScienceDaily via social networks and mobile apps:

Have Feedback?


Tell us what you think of ScienceDaily -- we welcome both positive and negative comments. Have any problems using the site? Questions?
Mobile iPhone Android Web
Follow Facebook Twitter Google+
Subscribe RSS Feeds Email Newsletters
Latest Headlines Health & Medicine Mind & Brain Space & Time Matter & Energy Computers & Math Plants & Animals Earth & Climate Fossils & Ruins