Planets Mars InSight Mission Cleared for 2018 Launch The spacecraft missed its launch opportunity this month due to a small leak in its primary science instrument.

NASA has decided to proceed with the InSight mission to Mars, with launch now targeted for May 2018. The spacecraft missed its launch opportunity this month due to a small leak in its primary science instrument, a seismometer that is designed to study the deep interior of Mars. Photos: 12 Years On Mars: Rover Opportunity's First Sols NASA grounded the mission for review in late December after a vacuum chamber housing the seismometer's sensors failed a leak test. "The quest to understand the interior of Mars has been a longstanding goal of planetary scientists," John Grunsfeld, NASA's associate administrator for science, said in a statement. "We're excited to be back on the path for a launch." The agency said it was reviewing how much the repair and launch delay would cost, but the project scientist estimates it will be about $150 million. The Dust Devils of Mars Could Pack a Seismic Punch NASA said it should know the final tab in August after it selects a new launch vehicle. The Atlas 5 rocket that was being prepared to fly Insight was re-assigned to another spacecraft. InSight will be put into storage near Denver while the seismometer's vacuum chamber is re-designed, said spacecraft builder Lockheed-Martin.

Mars is the target for the revamped InSight mission that will study the planet’s interior.

Scientists are meeting this week to discuss landing sites for NASA’s next Mars rover, an ambitious mission that not only will attempt to look for past life on Mars, but also stash samples drilled out from rocks for a future rover to retrieve and fly back to Earth for analysis. The point of the meeting is to discuss the current top candidate landing sites, though the list likely will change as new images and science data come in from satellites orbiting Mars and from NASA’s ongoing Curiosity and Opportunity rover missions. MORE: Watching the Sunsets of Mars Through Robot Eyes The new mission, still generically referred to as Mars 2020, is due to blast off in July or August 2020 and land itself in February 2021 using a heat shield, parachutes and Curiosity’s “skycrane” tethered descent system (pictured here). Engineers also are working to develop a “terrain recognition navigation” system that would allow the descending spacecraft to take pictures and match them with imagery stored in its computer for more precise steering. That system could make many more potential landing sites safe for touchdown. Another concern is how fast the rover could traverse the surface so that it can meet its mission goals, including drilling and cache 20 samples, in one Martian year, or 668 Earth days.) Here’s a look at some of the leading landing site contenders.

Tucked between a large volcano and an ancient impact basin is a region known as Nili Fossae, which is marked by wide, curved troughs cutting about 1,600 feet into the Martian crust. Nili Fossae is replete with clay-rich rocks, which form in the presence of water and which may be key to finding preserved organics. Nili Fossae was a top candidate for NASA’s ongoing Curiosity mission, but the site was cut due to engineering concerns. MORE: Top 10 Space Robot 'Selfies'

Scientists believe water once flowed and pooled inside an ancient crater known as Jezero, located near the Martian equator. The water streamed in from the northern and western sides of the crater, now marked by dried out channels, and eventually overflowed the crater’s southern wall, creating a third channel. Scientists do not know how long the water existed, though they do think there were at least two separate water events before the area dried out between 3.5 billion and 3.8 billion years ago. Chemical data collected by Mars orbiters show Jezero has clay and carbonate minerals that were altered by water. If life evolved during the time when Jezero was flush with water, it may be preserved in the sediments. MORE: NASA Injects New Funds Into Search for Origins of Life

Ancient exposed bedrock and a diverse collection of hydratated minerals got this site a spot on the Mars 2020 candidate landing list. The targeted zone is located in the northeast part of Syrtis Major, a huge shield volcano and near the northwest rim of the giant impact basin Isidis Planitia. MORE: Alien Robots That Left Their Mark on Mars

Scientists took a long, hard look at 100-mile wide Holden Crater before deciding to send the Curiosity rover to Gale Crater instead for a mission to assess if Mars ever had all the ingredients necessary for life. That goal was met less than seven months after the rover’s Aug. 3, 2012, touchdown. Holden, along with Eberswalde Crater and Mawrth Vallis, made to the short list of Curiosity candidate landing sites and remains of interest to scientists on the follow-on Mars 2020 mission to actually look for signs of ancient life and cache samples for an eventual return to Earth. MORE: NASA Plans 'Curiosity Twin' Rover Mission in 2020 Holden Crater was once believed to have been “Holden Lake.” It contains two layers of sediments, the lower of which is believed to have formed in a large lake. The upper layer likely formed when water pooled in an area to the south known as Uzboi Vallis broke through Holdin’s rim. The current must have been strong, capable of transporting boulders dozens of feet in diameter. Within Holden’s ancient basin are numerous smaller craters, many of which are filled with sediments.