Mark C. Ivanov

Overview of the NASA Entry, Descent and Landing Systems Analysis Study

NASA senior management commissioned the Entry, Descent and Landing Systems Analysis (EDL-SA) Study in 2008 to identify and roadmap the Entry, Descent and Landing (EDL) technology investments that the agency needed to make in order to successfully land large payloads at Mars for both robotic and human-scale missions. This paper summarizes the approach and top-level results from Year 1 of the Study, which focused on landing 10–50 mt on Mars, but also included a trade study of the best advanced parachute design for increasing the landed payloads within the EDL architecture of the Mars Science Laboratory (MSL) mission.

Toward improved landing precision on Mars

Mars landers to date have flown ballistic entry trajectories with no trajectory control after the final maneuver before entry. 12Improvements in landing accuracies (from ∼150 km from the target for Mars Pathfinder to ∼30–40 km for MER and Phoenix) have been driven by approach navigation improvements. MSL will fly the first guided-entry trajectory to Mars, further improving accuracy to ∼10–12 km from the target. For future missions, landing within ∼100m is desired to assure landing safety close to a target of high scientific interest in irregular terrain, or to land near a previously landed asset. Improvements in approach navigation alone are not sufficient to achieve this requirement. If approach navigation error and IMU error are eliminated, the dominant error source is wind drift on the parachute, with map-tie error also significant. Correcting these errors requires terrain-relative navigation (TRN), which can be accomplished with passive imaging supplemented by radar for terrain sensing (with onboard navigation capable of processing measurements from IMU, imaging, and radar). Additionally, near-optimal-ΔV powered descent guidance is needed to minimize the amount of propellant required to reach the target. The capability to land within 100m can be applied in different landing modes depending on how much fuel is carried.

Mars Science Laboratory entry guidance improvements study for the Mars 2018 mission

In 2011, the Mars Science Laboratory (MSL) was launched in a mission to deliver the largest and most capable rover to date to the surface of Mars. A follow on MSL-derived mission, referred to as Mars 2018, is being proposed to launch in 2018. Mars 2018 is investigating performance enhancements of the Entry, Descent and Landing (EDL) system over that of its predecessor MSL mission of 2011. This paper will discuss the main elements of the proposed Mars 2018 EDL preliminary design that are being considered to increase performance on the entry phase of the mission. In particular, these elements are discussed with the goals of increasing the parachute deploy altitude to allow for more time margin during the subsequent descent and landing phases, increasing the entry mass, and reducing the delivery ellipse size at parachute deploy, through modifications in the entry reference trajectory design, vehicles lift to drag ratio, parachute deploy trigger logic design, and the effect of additional navigation hardware.

Overview of the NASA Entry, Descent and Landing Systems Analysis Studies for Large Robotic-class Missions

NASA senior management commissioned the Entry, Descent and Landing Systems Analysis Study in 2008 to identify and roadmap the Entry, Descent and Landing technology investments that the agency needed to make in order to successfully land large payloads at Mars for both robotic and human-scale missions. This paper summarizes the approach and top-level results from Year 2 of the Study, which focused on landing 1‐4 mt on Mars for robotic missions. Two separate studies were conducted in Year 2: the Mars Science Laboratory Improvement Study, which determined technology development program needs to support increases in landed payload and landed altitude beyond the Mars Science Laboratory capability using an Atlas V launch vehicle and the Exploration Feed-Forward Study, which examined a potential precursor mission using a Delta IV-H launch vehicle with landed payload in the 2‐4 mt range that would demonstrate key technologies needed for later human missions.

LDSD supersonic Flight Dynamics Test 1: Post-flight reconstruction

The Low Density Supersonic Decelerator projects first Supersonic Flight Dynamics Test (SFDT) occurred on June 28, 2014, off the west coast of Kauai, Hawaii, over the Pacific Ocean. The test vehicle traveled to speeds above Mach 4 and to an altitude of over 200,000 feet. This flight, although classified as a test architecture shake-out flight, tested two technologies: a robotic class Supersonic Inflatable Aerodynamic Decelerator and a Supersonic Disksail Parachute. The reconstruction team was tasked with collecting all relevant pre-flight and flight data to accurately reconstruct the trajectory and technology performance during the science phase of the flight. Furthermore, the reconstruction team has been involved with reconstructing and exploring all aerodynamic and test vehicle properties that affected the entire flight phase. This reconstruction provided insight into the technology performance, which is a key deliverable for the LDSD project, as well as provided insight into lessons learned for subsequent SFDT flights, in the fields of data recovery, reconstruction, and pre-flight trajectory simulations.

SuperSmart Parachute Deployment Algorithm for Mars Pinpoint Landing

An algorithm for choosing the parachute deployment point has been developed which is designed to reduce delivery errors at powered descent ignition during Entry / Descent / Landing (EDL) on a body with an atmosphere (e.g. Mars), consequently reducing the propellant required to achieve precise landing at a preselected target. This algorithm is designed to improve on the previously developed “Smart Chute” deployment algorithm by modeling the lander’s trajectory during the parachute phase for improved targeting. Performance benefits are influenced by environmental factors, principally winds between chute deployment and ignition, which cause the lander to drift on the parachute.