Legacy of NASA's Dawn, Near the End of its Mission
NASA's Dawn mission is drawing to a close after 11 years of breaking new ground in planetary science, gathering breathtaking imagery, and performing unprecedented feats of spacecraft engineering.
Dawn's mission was extended several times, outperforming scientists' expectations in its exploration of two planet-like bodies, Ceres and Vesta, that make up 45 percent of the mass of the main asteroid belt. Now the spacecraft is about to run out of a key fuel, hydrazine. When that happens, most likely between mid-September and mid-October, Dawn will lose its ability to communicate with Earth. It will remain in a silent orbit around Ceres for decades.
[...] Because Ceres has conditions of interest to scientists who study chemistry that leads to the development of life, NASA follows strict planetary protection protocols for the disposal of the Dawn spacecraft. Unlike Cassini, which deliberately plunged into Saturn's atmosphere to protect the system from contamination -- Dawn will remain in orbit around Ceres, which has no atmosphere.
Engineers designed Dawn's final orbit to ensure it will not crash for at least 20 years -- and likely decades longer.
Previously: Dawn's Orbit Around Ceres: A New Low
Dawn Spacecraft Captures Closest-Ever Images of Ceres' Shiny Occator Crater
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Previously, NASA planned to lower the closest approach to Ceres of the Dawn spacecraft to around 120 miles (200 km) from 239 miles (385 km). Now, the XMO7 orbit will reach an altitude of just 22 miles (35 km) above Ceres. The images returned should be over 9000 times better than what Hubble can capture. This is the final orbit planned:
NASA's Dawn spacecraft is maneuvering to its lowest-ever orbit for a close-up examination of the inner solar system's only dwarf planet.
In early June, Dawn will reach its new, final orbit above Ceres. Soon after, it will begin collecting images and other science data from an unprecedented vantage point. This orbit will be less than 30 miles (50 kilometers) above the surface of Ceres -- 10 times closer than the spacecraft has ever been.
Dawn will collect gamma ray and neutron spectra, which help scientists understand variations in the chemical makeup of Ceres' uppermost layer. That very low orbit also will garner some of Dawn's closest images yet.
The transfer from Dawn's previous orbit to its final one is not as simple as making a lane change. Dawn's operations team worked for months to plot the course for this second extended mission of the veteran spacecraft, which is propelled by an ion engine. Engineers mapped out more than 45,000 possible trajectories before devising a plan that will allow the best science observations.
Previously: Dawn Mission Extended at Ceres
Related: Ceres May Have Had a Global Surface Ocean in the Past
Evidence of a Seasonal Water Cycle and Surface Changes Found on Ceres
Dawn spacecraft captures new images of Ceres' Occator Crater
NASA's Dawn spacecraft has entered into its final planned orbital position from which it will study the dwarf planet Ceres, the lowest the probe has descended to the tiny world since it arrived in orbit on March 6, 2015.
The probe is powered by three xenon ion thrusters and it enter[ed] into its new orbit around the dwarf planet on June 6, 2018. Since then, the spacecraft has begun beaming back to Earth stunning new and closer images of this tiny worldlet.
One of Dawn's targets is Occator Crater. While the name might not ring a bell even among space enthusiasts, the "bright spots" contained within the crater should. These deposits are thought to be salt from briny water that erupted from the dwarf planet's surface before sublimating. It was found that the bright regions were comprised of sodium carbonate. On Earth, these salts are left behind when water evaporates.
Dawn was instructed to fire its ion engine—for what could be the last time—last week. By carrying out this maneuver, the probe flew closer to the dwarf planet's Cerealia Facula. This is the region of Occator Crater that contains a large deposit of sodium carbonate.
Perhaps more important than the cool photographs will be the data collected by the spacecraft's two other instruments, and particularly the Gamma Ray and Neutron Detector (GRaND).
Previously: Ceres Bright Spots Seen Closer Than Ever
Life On Ceres? Mysterious Changes in the Bright Spots Still Baffle Scientists
Bright Areas on Ceres Suggest Geologic Activity
Evidence of a Seasonal Water Cycle and Surface Changes Found on Ceres
Dawn's Orbit Around Ceres: A New Low
Dawn's Orbit Around Ceres: First Images
NASA Retires Kepler Space Telescope
After nine years in deep space collecting data that indicate our sky to be filled with billions of hidden planets - more planets even than stars - NASA's Kepler space telescope has run out of fuel needed for further science operations. NASA has decided to retire the spacecraft within its current, safe orbit, away from Earth. Kepler leaves a legacy of more than 2,600 planet discoveries from outside our solar system, many of which could be promising places for life.
"As NASA's first planet-hunting mission, Kepler has wildly exceeded all our expectations and paved the way for our exploration and search for life in the solar system and beyond," said Thomas Zurbuchen, associate administrator of NASA's Science Mission Directorate in Washington. "Not only did it show us how many planets could be out there, it sparked an entirely new and robust field of research that has taken the science community by storm. Its discoveries have shed a new light on our place in the universe, and illuminated the tantalizing mysteries and possibilities among the stars."
NASA's Dawn Mission to Asteroid Belt Comes to End
NASA's Dawn spacecraft has gone silent, ending a historic mission that studied time capsules from the solar system's earliest chapter.
Dawn missed scheduled communications sessions with NASA's Deep Space Network on Wednesday, Oct. 31, and Thursday, Nov. 1. After the flight team eliminated other possible causes for the missed communications, mission managers concluded that the spacecraft finally ran out of hydrazine, the fuel that enables the spacecraft to control its pointing. Dawn can no longer keep its antennae trained on Earth to communicate with mission control or turn its solar panels to the Sun to recharge.
The Dawn spacecraft launched 11 years ago to visit the two largest objects in the main asteroid belt. Currently, it's in orbit around the dwarf planet Ceres, where it will remain for decades.
Also at Ars Technica, The Verge, and Science News.
Previously: NASA's Dawn Spacecraft Nears the End of its Mission
NASA Retires the Kepler Space Telescope after It Runs Out of Hydrazine
Related:
Pluto and Ceres
After Eight Years, NASA's Dawn Probe Brings Dwarf Planet Ceres Into Closest Focus
NASA's Dawn Orbiter Finds a Mountain on Ceres
Dawn Spies Magnesium Sulphate and Possible Geological Activity on Ceres
Ceres' Cryovolcano Ahuna Mons Formed in the Geologically Recent Past
Ceres's Cryovolcanoes Viscously Relax Into Nothingness
Organic Molecules Found on Ceres
Early Asteroids May Have Been Made of Mud Rather Than Rock
Dawn Mission Extended at Ceres
Ceres May Have Had a Global Surface Ocean in the Past
Bright Areas on Ceres Suggest Geologic Activity
Dawn's Orbit Around Ceres: A New Low
Dawn's Orbit Around Ceres: First Images
Dawn Spacecraft Captures Closest-Ever Images of Ceres' Shiny Occator Crater
(Score: 0) by Anonymous Coward on Tuesday September 11 2018, @08:19AM (1 child)
Silent orbit around an asteroid, a body devoid of life. No data to collect, or send. Or stranded on a Red Planet, mired in sand, or with your solar panels permanently buried. This is what will happen to you if you work for NASA! Bots be forewarned!
(Score: 2) by bob_super on Tuesday September 11 2018, @05:14PM
Sure, but in how many other places does a 90-day gig turn into 14 years with full executive and team support, and people sad that you may be gone ?
(Score: 0) by Anonymous Coward on Tuesday September 11 2018, @08:19AM (3 children)
What ever happened to that wall they discovered surrounding the solar system? IIRC it was made of crystalline hydrogen and the voyager spacecraft hit it, then they saw it coming into view with the craft that just imaged pluto.
(Score: 3, Informative) by takyon on Tuesday September 11 2018, @10:08AM
https://en.wikipedia.org/wiki/Heliosphere#Hydrogen_wall [wikipedia.org]
[SIG] 10/28/2017: Soylent Upgrade v14 [soylentnews.org]
(Score: 1) by khallow on Tuesday September 11 2018, @11:47AM (1 child)
Apparently, there's "metallic" hydrogen [wikipedia.org] which is thought to have a crystalline structure, but that has a density somewhere around 800 kg per cubic meter and requires a pressure of around 4 million atmospheres to exist. It's not going to exist in a rarefied space environment (with a pressure of almost 0 atmospheres) and any spacecraft hitting it at Voyager speeds would disintegrate. Finally, it's conductive, so it would act as a crude mirror, meaning we'd see a lot of sunlight coming back at us, while simultaneously not seeing stars beyond the wall.
(Score: 0) by Anonymous Coward on Tuesday September 11 2018, @11:47PM
You are saying it must be artificial then? My best bet is it was created by the Pleiadians to keep humanity quarantined until it is safe to let us out. Voyager was like the baby bird's beak cracking open the egg and new horizons is the claw coming to tear open the first piece.