ROSETTA PROBE MISSION:
AdminCadet: Europe’s Rosetta probe is reaching it’s comet destination after approximately ten years. The first image below is a view of the comet 67P/Churyumov-Gerasimenko taken on June 28, 2014, at a distance of about 86,000 km (approx 53,000 miles) between the probe and the comet. The second image is a Rosetta navigation camera (NavCam) view of the comet Churyumov-Gerasimenko, taken one month later on August 3, 2013, at a distance of approximately 300 km (186 miles).
An nbcnews.com discussion of the ESA (European Space Agency) mission, published August 3, 2014, is available at the following link:
Image of Comet 67P/Churyumov-Gerasimenko on 28 June 2014 (approx 86,000 km / 53,000 miles):
Image of Comet 67P/Churyumov-Gerasimenko on 3 August 2014 (approx 300 km / 186 miles):
Further images and information on the Rosetta mission can be found at the following ESA sites:
OPINION: AdminCadet: On a separate discussion more related to our US NASA program, note the non-spherical shape of the comet in the second image compared to the fuzzy round shape that appears in the first image. As the two images show, it is very difficult to ascertain the real shape of the comet depending on distance from the object. The comet’s real shape and characteristics are much more evident when taken from a closer distance, as would be expected. However, the differences between the two images demonstrate pretty clearly how difficult it will be for NASA to select an asteroid from a great distance for the Asteroid Retrieval/Redirect Mission (ARM) currently in planning. NASA management has mandated the ARM as NASA’s new human space exploration mission. It entails robotically retrieving an asteroid and returning it to Earth-Moon space to allow astronauts to physically sample and retrieve material from the asteroid. Some space cadets worry that the inability to accurately determine the shape and make up of an asteroid from a distance will make designing the initial robotic retrieval portion of the mission very difficult, if not impossible. [On a side note: It will be interesting to see what detection methods will be developed to select the right asteroid target for the ARM].
Another issue of the ARM mission concerns the delays this would establish in human exploration activities. Once the asteroid is brought to Earth-Moon space, the astronauts would utilize the in-design / build Orion capsule and Space Launch System Rocket (SLS) to reach the retrieved asteroid. Unfortunately, the retrieval portion of the mission could take as long as seven to ten years due to the propulsion systems required for the robotic vehicle, resulting in no human space operations until potentially the late 2020s or early 2030s (depending when the mission was initiated). This would mean further postponement of US human exploration activities (and potential loss of skills) in the meantime except for those related to the international space station.
Per Wikipedia: “As of June 2014 more than 1,000 new near-Earth asteroids have been discovered by various search teams and catalogued by NASA’s Near-Earth Object Observation Program. Twenty of those identified so far could be good candidates for ARM. On June 19, 2014, NASA reported that asteroid 2011 MD was a prime candidate for capture… perhaps in the early 2020s… 2011 MD is an… asteroid that passed relatively close to Earth’s surface – at a distance of about 12,000 kilometers (7500 miles), roughly the diameter of the Earth… on June 27, 2011… 2011 MD was observed by the Spitzer Space Telescope in February 2014 and estimated to be 6 meters (20 ft) in diameter. The asteroid is a porous rubble pile with a density similar to water…”
The third image below shows 2011 MD viewed in February 2014 by the Spitzer Space Telescope, IRAC.
Image of 2011 MD Asteroid in February, 2014:
IN CONCLUSION: Perhaps going back to the Moon, a well mapped Near-Earth Object, would make more sense instead of chasing after an asteroid of imperfectly determined size and composition in a mission that could take up to two decades to initiate and complete. Planning and conducting robotic and human missions to the Moon are sensible and well-advised first steps toward future Mars and outer planetary human exploration missions. The ARM mission, except for enabling improvements in long distance detection sensors (admittedly a worthy goal), does not seem to provide a reasonable stepping stone toward direct human exploration of our solar system.
Rosetta Article credit: nbcnews.com – Mike Wall – August 3, 2014
Photo Imagery Credits:
Images 1 and 2 (and accompanying information): Comet 67P/Churyumov-Gerasimenko, ESA/Rosetta/MPS for OSIRIS Team MPS/UPD/LAM/IAA/SSO/INTA/UPM/DASP/IDA, June 28, 2014 and August 4, 2014 [taken from ESA site: blogs.esa.int/rosetta/]
Image 3: Asteroid 2011MD, Spitzer Space Telescope, IRAC, February 2014.
2011 MD Asteroid Information Credit: Wikipedia.