Lessons learned from the impressive Entry Descent and Landing (EDL) of the Mars Science Laboratory (MSL) are set to provide the next NASA Rover with improved landing skills. Although the 2020 Mars Rover will have a similar appearance to Curiosity, she will sport new scientific payloads and additional capabilities – not least the potential to “pinpoint” a landing at a high priority target.
NASA isn’t resting on its laurels when it comes its dominance in successfully landing spacecraft on the surface of the Red Planet.
The stunning success of Curiosity’s touchdown on August 6, 2012 not only begun another Martian adventure, it also increased the knowledge base on the requirements and potential improvements for safely landing on Mars.
The data was collated by the Mars Science Laboratory Entry Descent and Landing Instrument (MEDLI).
MEDLI was provided to Curiosity’s mission by NASA’s Langley and Ames Research Centers. Consisting of two instruments, each with seven sensors, the data during the spacecraft’s high-speed entry into the Martian atmosphere was collected from 14 locations on the spacecraft’s heat shield.
Per the recent HEO (Human Exploration and Operations Mission Directorate and SMD (Science Mission Directorate) Joint Activities presentation to the NASA Advisory Council (NAC), the data provided a wealth of information that will be fed into the development of the 2020 Rover.
“MEDLI consisted of 7 heat shield pressure ports, 7 integrated sensor plugs, and support electronics. MEDLI gathered engineering data during MSL’s entry and descent for future Mars missions. (This included) aerothermal, aerodynamic, and thermal protection system performance, atmospheric density and winds,” noted the overview.
“The MEDLI suite made MSL the first extensively instrumented heat shield ever sent to Mars.”
Although extensive evaluations took place via computational models and ground testing ahead of the mission, only a real life Martian entry could provide the required updates to the knowledge base.
The results from Curiosity’s dive towards the Martian surface show the 2020 Rover will enjoy the allowance of a lighter Thermal Protection System (TPS).
“Reduced required aerothermal environment and TPS design margins Potential 40 percent to 50 percent reduction in forebody TPS thickness, resulting in around 100 kg mass saving. Eliminated unknown unknowns that could not be addressed by ground testing,” the overview listed.
“Improved reconstruction of guided hypersonic entry. Separated capsule aerodynamics from atmospheric contributions to deceleration. Independent pressure measurements provided a density profile to both engineers and scientists.
“Validated pre-flight predicted Aerodynamics. Measured trim angle agrees to within 0.5 deg. Measured drag agrees to within 1-2 percent.”
Thanks to Curiosity’s data, the team’s presentation to the NAC outlined some of the improved knowledge they can employ on the 2020 Rover.
This includes improved supersonic aerodynamics resolution and backshell measurement, improved near-surface thermal resolution and improved spatial thermal resolution.
However, it is the 2020 Rover’s EDL refinements that could allow for a “precision” landing on the Red Planet.
Any potential increase in the landing site accuracy will be some feat, given Curiosity successfully targeted a landing ellipse area at Gale Crater that was just 25km by 20km, refined down to 20km by 7km.
This is in striking contrast to the much larger 150 by 20km (93 by 12mile) landing ellipses used for the Mars Exploration Rovers Spirit and Opportunity back in 2004.
To accomplish such a feat, Mars Science Laboratory engineers designed a new high-precision EDL system.
This consisted of six different spacecraft configurations, 76 pyrotechnic devices, the largest supersonic parachute ever designed and manufactured, and more than 500,000 lines of code to execute the required maneuvers to safely ease Curiosity on to the surface.
For the 2020 Rover, the path toward touchdown will be similar, employing the four main phases of EDL: Guided Entry, Parachute Descent, Powered Descent, and Sky Crane landing.
However, per the presentation to the NAC, the team for the next Rover is studying the inclusion of improved Terrain Relative Navigation (TRN).
This works by taking images during parachute descent & matching them to an onboard map, using a dedicated compute element, camera and an inertial measurement unit.
This will “yield a position solution and performs terrain relative navigation while the spacecraft is priming the descent engines. Operating during priming imposes no altitude cost”.
Also listed is the Multi-Point Divert (MPD) technique, which uses position solutions and a list of safe landing locations to select a landing target.
This “augments original MSL backshell avoidance divert and uses original divert distance capability (no additional fuel or altitude needed).”
The refinements hold the potential “to land on high priority scientific targets previously out of reach, shorten drive,” as some of the examples as to why the 2020 Mars Rover mission “offers many important advances relative to MER and MSL”.
The ability to ever-increase precision touchdowns on Mars has a path toward the eventual human landings on the Red Planet, as previously highlighted by John Grunsfeld, Associate Administrator of NASA’s Science Mission Directorate.
“Looking down the road, there’s a whole list of topics in technology and precision landing. You would like future crews to say ‘we’re going to land right next to the cargo ship that I landed to previously’. If you’re many kilometers away, that’s not right next to it. You want to be meters away,” noted Dr. Grunsfeld.
The synergy between the Rovers and the eventual crewed missions to Mars are a key element of the NASA roadmap, as much as the human element remains highly undefined.
“If we think of the 2030s as the potential for human exploration of Mars, I think this 2020 rover – and the other things we might be able to do in the 2020s – will provide a synergistic collaboration between science and human space flight,” added Dr. Grunsfeld.
“There’s a lot of cool things we can do with advancements, both in science and exploration.”
(Images: Via NASA, NASA JPL and L2).
(L2 is – as it has been for the past several years – providing full exclusive SLS and Exploration Planning coverage. To join L2, click here: http://www.nasaspaceflight.com/l2/)