NASA achieves another milestone. Its Dawn spacecraft has become the first to orbit a dwarf planet. Ceres’ gravity grabbed ahold of Dawn at 7:39 am EST on Friday.
“Since its discovery in 1801, Ceres was known as a planet, then an asteroid and later a dwarf planet,” said Marc Rayman, Dawn’s chief engineer and mission director. “Now, after a journey of 3.1 billion miles and 7.5 years, Dawn calls Ceres, home.”
The latest image of Ceres can be seen above. Right now, Dawn is on the dark side of Ceres. By mid-April, Dawn will emerge from the dark side and give us the best images of Ceres ever taken.
“We feel exhilarated,” said Chris Russell, the principal investigator of the Dawn mission. “We have much to do over the next year and a half, but we are now on station with ample reserves, and a robust plan to obtain our science objectives.”
Dawn also notched another milestone on Friday. It has become the first spacecraft to orbit two extraterrestrial targets. In 2011-2012, Dawn surveyed the asteroid Vesta and snapped thousands of pictures. Vesta, along with Ceres, are two of the biggest objects in our solar system’s main asteroid belt between Mars and Jupiter.
The four largest objects in the asteroid belt – Ceres, Vesta, Pallas and Hygiea – make up nearly half the mass of the entire asteroid belt. You might imagine the asteroid belt between Mars and Jupiter is dense and full of asteroids. But, several spacecraft have made the journey through the asteroid belt without any problems.
What Should We Expect from Dawn Now?
According to NASA, Dawn will conduct a “prime science phase” from April 2015 through June 2016. The Dawn spacecraft will go through several phases during this prime science phase. In April and May, Dawn will be within about 8,400 miles of Ceres.
In June, the spacecraft will dive to around 2,730 miles. For 22 days in June, Dawn will use its camera and the visible and infrared mapping spectrometer (VIR) to get a global view of Ceres.
Dawn will dive even further towards Ceres in August where it will be 910 miles above the dwarf planet’s surface. This phase is called high-altitude mapping orbit (HAMO). It will continue to observe Ceres with its camera and VIR, and it will also image Ceres’ surface in ‘stereo’ for 3-D imaging.
Dawn will reach its closest point to Ceres in December. On December 15th, Dawn will be just 230 miles above Ceres’ surface. Dawn’s gamma ray and neutron detector (GRaND) will look for signatures of elements on Ceres’ surface.
Dawn’s mission will eventually come to an end sometime in June 2016. The spacecraft will continue orbiting Ceres, but it will no longer be operating. Since Ceres may have water ice on its surface, the NASA Planetary Protection Office requires Dawn not hit Ceres for at least 20 years. Dawn’s project team decided to choose a final orbit that will not impact the dwarf planet for at least 50 years.
As for those mysterious bright spots on Ceres? Hopefully, we will know more by June.