Dawn’s voyage of discovery comes to a close
After more than a decade traveling through space and exploring asteroids and dwarf planets, NASA’s Dawn mission has come to a close. The most likely reason the probe ceased communicating with mission managers on the ground is that it has run out of fuel.
The spacecraft utilizes hydrazine, a highly-toxic fuel source that Soviet rocket engineers referred to as “the devil’s venom.” In the case of Dawn however, this “venom” enabled one of the most successful exploration missions of the past decade.
Between Oct. 31 and Nov. 1, mission managers attempted to contact the spacecraft during regularly scheduled communication sessions. NASA utilized the agency’s Deep Space Network to reach out to Dawn, which is orbit above the dwarf planet Ceres.
“The fact that my car’s license plate frame proclaims, ‘My other vehicle is in the main asteroid belt,’ shows how much pride I take in Dawn,” said Mission Director and Chief Engineer Marc Rayman at NASA’s Jet Propulsion Laboratory. “The demands we put on Dawn were tremendous, but it met the challenge every time. It’s hard to say goodbye to this amazing spaceship, but it’s time.”
Since its mission began in 2007, the spacecraft has traveled approximately 4.3 billion miles (6.9 billion kilometers).
“In many ways, Dawn’s legacy is just beginning,” said Principal Investigator Carol Raymond at JPL. “Dawn’s data sets will be deeply mined by scientists working on how planets grow and differentiate, and when and where life could have formed in our solar system. Ceres and Vesta are important to the study of distant planetary systems, too, as they provide a glimpse of the conditions that may exist around young stars.”
Members of the Dawn team concluded that the most likely cause of its silence was that it had run out of fuel. With its inability to point its antenna back to Earth or to turn its solar arrays toward the Sun – the spacecraft has fallen silent without the ability to recharge.
Following the protocols that the Planetary Protection Office has laid out, the spacecraft is in an orbit that should see it orbit the tiny world for at least 20 years (some estimates place it as long as 50 years).
Dawn is a project of the directorate’s Discovery Program, managed by NASA’s Marshall Space Flight Center in Huntsville, Alabama. The Northrop Grumman-built spacecraft was launched on the Delta II 7925H rocket tapped to send the spacecraft on the first leg of its voyage by United Launch Alliance. Lifting off from Cape Canaveral Air Force Station’s Space Launch Complex 17B located in Florida on September 27, 2007.
The spacecraft carries four science experiments that studied the geology of its two targets, providing scientists with a better understanding as to how they and other bodies in the asteroid belt formed. Strange formations on Ceres suggested that some of these worlds might have once held oceans.
Using ion engines, Dawn was able to circle the asteroid Vesta before breaking orbit and moving on to Ceres. In so doing it made history—Dawn was the first spacecraft to visit a dwarf planet and the first to orbit two worlds.
“Today, we celebrate the end of our Dawn mission – its incredible technical achievements, the vital science it gave us, and the entire team who enabled the spacecraft to make these discoveries,” said Thomas Zurbuchen, associate administrator of NASA’s Science Mission Directorate in Washington. “The astounding images and data that Dawn collected from Vesta and Ceres are critical to understanding the history and evolution of our solar system.”
Jason Rhian spent several years honing his skills with internships at NASA, the National Space Society and other organizations. He has provided content for outlets such as: Aviation Week & Space Technology, Space.com, The Mars Society and Universe Today.
“Using ion engines, Dawn was able to circle the asteroid Vesta before breaking orbit and moving on to Ceres. In so doing it made history—Dawn was the first spacecraft to visit a dwarf planet and the first to orbit two worlds.”
– Jason Rhian
Electric propulsion systems with high 3,000 Isp to 14,000+ Isp (that are similar to the Electric Propulsion system used by the Dawn spacecraft) combined with Nuclear Thermal Propulsion, or NTP, rocket engines with an Isp of 900+ could probably provide the transportation efficiency and high delta-v needed for mining asteroids.
Chemical rocket engines with a 360 Isp to 465 Isp are most likely far too inefficient to enable sustainable, cost effective, and robust human missions across our Solar System.
“UK’s first electric propulsion system for satellites to leave Belfast factory” By Ben Sampson 11/1/2018
“Nuclear Thermal Propulsion: Game Changing Technology for Deep Space Exploration” Editor: Loura Hall May 25, 2018