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Two out of three missions to the red planet have failed. One reason there have been so many losses is that there have been so many attempts. “Mars is a favorite target,” says Dr. Firouz Naderi, manager of the Mars Program Office at the Jet Propulsion Laboratory. To get there, Spirit and Opportunity, the two Mars Exploration Rovers launched this past June and July, will have to fly through about 483 million kilometers (300 million miles) of deep space and target a very precise spot to land. Adjustments to their flight paths can be made along the way, but a small trajectory error can result in a big detour and or even missing the planet completely.
If getting to Mars is hard, landing there is even harder. “One colleague describes the entry, descent and landing as six minutes of terror,” says Naderi. So, the challenge of entry, descent and landing is how to get something that massive traveling at 19,300 kilometers per hour (12,000 miles per hour) slowed down in six minutes to have a chance of survival.”
Satellites also face many Challenges of Space environment such as vacuum, high-temperature changes regarding nonconductive thermal feature of vacuum typically between −150 and 150°C, outgassing or material sublimation which can create contamination for payloads especially on lens of cameras, ionizing or cosmic radiation (beta, gamma, and X-rays), solar radiation, atomic oxygen oxidation or erosion due to the atmospheric effect of low earth orbiting.
The first hurdle for space systems to overcome is the vibration imposed by the launch vehicle. Rocket launchers generate extreme noise and vibration. When a satellite separates from the rocket in space, large shocks occur in the satellite’s body structure. Satellite must survive the extreme vibrations and acoustic levels of the launch. Pyrotechnic shock is the dynamic structural shock that occurs when an explosion occurs on a structure. Pyroshock is the response of the structure to high frequency, high magnitude stress waves that propagate throughout the structure as a result of an explosive charge, like the ones used in a satellite ejection or the separation of two stages of a multistage rocket. Pyroshock exposure can damage circuit boards, short electrical components, or cause all sorts of other issues.
Another obstacle is the very high temperature fluctuations encountered by a spacecraft. Because it is closer to the Sun, the temperature fluctuations on a satellite in GEO stationary orbit will be much greater than the temperature variations on a satellite in LEO. Thermal cycling occurs as the spacecraft moves through sunlight and shadow while in orbit that can cause cracking, crazing, delamination, and other mechanical problems, particularly in assemblies where there is mismatch in the coefficient of thermal expansion.
Radiation effects (total dose, latchup, single event upsets) are one of the main concerns for space microelectronics. The design of radiation-hardened integrated circuits ( RHlCs ) involves four primary efforts. First is the selection of a technology and process which are relatively insensitive to the projected application environment of the IC.
Whether the satellite is for the government, the military or private industry, the need for rigorous testing remains the same. If a private company is going to build satellites for the government or a commercial concern, they won’t retain that business for very long if the satellites they build don’t operate appropriately after launching into orbit — all of which means anyone involved in the satellite industry, the government or private, needs satellite testing.
NASA Flight Opportunities program
Flight Opportunities facilitates rapid demonstration of promising technologies for space exploration and the expansion of space commerce through suborbital testing with industry flight providers. The program matures capabilities needed for NASA missions while strategically investing in the growth of the U.S. commercial spaceflight industry. Flight Opportunities is funded by NASA’s Space Technology Mission Directorate (STMD).
Technology Readiness Levels (TRL) are a type of measurement system used to assess the maturity level of a particular technology. Each technology project is evaluated against the parameters for each technology level and is then assigned a TRL rating based on the projects progress. There are nine technology readiness levels. TRL 1 is the lowest and TRL 9 is the highest.
Technology Readiness Level (TRL) is a measure used to assess the maturity of evolving technologies (materials, components, devices, etc.) prior to incorporating that technology into a system or subsystem. TRL 6 means that System/subsystem model or prototype demonstration in a relevant environment. (ground or space) while TRL 7 means System prototype has been demonstrated in an operational (space) environment. TRL 8 technology has been tested and “flight qualified” and it’s ready for implementation into an already existing technology or technology system. Once a technology has been “flight proven” during a successful mission, it can be called TRL 9.
Flight Opportunities focuses on technologies that fall between 4 and 7 on NASA’s Technology Readiness Level
What is a “relevant environment”?
Flight Opportunities provides access to relevant testing environments up to the edge of space (approximately 80–100 km above sea level). These environments are relevant because they replicate some of the conditions encountered on orbital missions and beyond, such as extreme temperatures, microgravity conditions, radiation, and other factors. These conditions are difficult, and in some
cases impossible, to replicate in ground-based laboratory testing.
Flight testing on suborbital vehicles takes technologies from ground-based laboratories into relevant space-like environments to increase technology readiness and validate feasibility while reducing costs and technical risks of future missions. For the purposes of maturing technologies for future space exploration, a relevant environment typically means exposure to suborbital space. Often referred to as “the edge of space,” this environment is usually at an altitude at least 50 miles above sea level and/or replicates some of the conditions encountered in space, such as:
• Microgravity conditions, including weightlessness
• Limited re-entry conditions
• Challenging landing conditions
• High-altitude solar exposure
• Radiation
• Extreme temperatures and vacuum
• Intense spacecraft vibrations
By understanding how their payloads respond to these conditions, researchers are able to confirm their designs or make necessary refinements and improvements to mature their experiments before moving on to much more expensive orbital deployments, such as small satellites or lunar missions
Leveraging commercial vehicles
Flight Opportunities facilitates the purchase of commercial flight services for the demonstration of qualified technologies on rocket-powered suborbital vehicles, high-altitude balloons, and parabolic aircraft.
Between December 2018 and February 2019, 17 Flight Opportunities supported payloads were tested on three flights conducted by Virgin Galactic and Blue Origin. The flights carried a series of space exploration and utilization technologies, including research that could aid the ability of future missions to mitigate the impact of lunar surface dust on humans and equipment, separate gas and
liquid for in situ resource processing and on-orbit fuel transfer, and understand how to help plants thrive in space as a resource for sustained human activity on the Moon and beyond. Many of the payloads were flown multiple times and on both vehicles, underscoring the benefit of gathering data on different flight platforms and exhibiting the potential for rapid testing and reflight of technologies.
The vehicles are generally grouped into three categories:
• Parabolic aircraft –
Rocket-powered vehicles
These platforms include both suborbital reusable launch vehicles (sRLVs) that reach high altitudes and lander vehicles that specialize in entry, descent, and landing (EDL) technologies closer to the ground. Both of these classes of vehicles are typically recoverable and reusable after launch.
High-altitude balloons
Large balloon systems reach a minimum altitude of 16.5 miles and can typically sustain the longest duration of the suborbital platforms—hours, days, or even weeks at a time. This makes them ideal for payloads that benefit from extended periods of data collection.
Parabolic aircraft
These specialized airplanes achieve brief periods of variable gravity through a series of maneuvers called parabolas. They can be used for demonstrating technologies that need to operate in a specific gravity environment (e.g., lunar, Mars). These aircraft are ideal for demonstrating technologies that need to operate in zero gravity
Vertical Takeoff Vertical Landing (VTVL) Rockets
The vertical landing capability of these vehicles make them ideal for evaluating entry, descent, and landing systems.
• Evaluate planetary surface exploration methods
• Test landing vehicle and navigation capabilities
• Demonstrate hazard avoidance methods
Often, technologies matured through Flight Opportunities transition to missions in LEO that allow further validation of technical readiness beyond the threshold of suborbital demonstration.
The type of vehicle selected for testing depends on the required test conditions (e.g., gravity level needs, length of microgravity period). Figure 3 highlights the breakdown of flight vehicle types requested by researchers. In some cases, multiple flights on a combination of vehicle types were requested.
Many investigators leverage the ability to cost-effectively and rapidly access suborbital flights to test their technology multiple times on the same vehicle, making adjustments to the technology between flights. Others take advantage of the variety of suborbital vehicles offered by the commercial providers to test on multiple platforms, enabling investigation of technology performance in various environmental conditions.
In many cases, several technology payloads are carried on a single suborbital flight, enabling simultaneous technology tests with a single launch. As a result, through the 193 successful Flight Opportunities-supported flights, a total of 689 payloads tests have been conducted. These tests have played a significant role in advancing technologies that have been selected to provide critical capabilities for NASA missions.
Flight Opportunities program impact
Since 2011, Flight Opportunities has, as of June 30, 2020:
• Selected 262 technologies into the portfolio, approximately one-third of which have transitioned to missions, programs, commercial partners, or further testing
• Supported 193 successful flights
• Enabled 689 tests of payloads
• Worked with 12 active commercial flight providers
Over the course of ten years, a number of the flight-test proposals selected by Flight Opportunities have been evolutionary iterations of an initial innovation, resulting in a portfolio of approximately 160 distinct technologies that are of interest to NASA.
Current flight providers active with the program include:
• Angstrom Designs
• BlackSky Aerospace
• Blue Origin
• EXOS Aerospace Systems and Technologies
• Masten Space Systems
• Near Space Corporation
• Raven Aerostar
• Stratodynamics
• Virgin Galactic
• UP Aerospace
• World View Enterprises
• Zero Gravity Corporation
Facilitating in-space manufacturing
An additive manufacturing (3D printing) facility designed by Made In Space was matured through Flight Opportunities and is now installed on the International Space Station. Manufacturing of critical components in space can reduce operational costs and improve on-site repair capabilities for long-duration human exploration missions.
Testing a mechanically deployable heat shield
NASA’s Ames Research Center successfully demonstrated its Adaptable Deployable Entry and Placement Technology (ADEPT) through suborbital testing with Flight Opportunities. The foldable, umbrella-like heat shield opens to make a round, rigid structure with a diameter larger than the rocket it fits into. ADEPT could enable future NASA missions that require extra-large aeroshells to protect spacecraft destined to land on the surface of other planets—without requiring larger rocket fairings.
Enabling simpler planetary sample collection
Flight Opportunities facilitated a successful demonstration by Honeybee Robotics of its PlanetVac planetary sample collection system in the Mojave Desert, where ground conditions resemble those that researchers expect to encounter on planetary bodies. PlanetVac successfully collected more than 300 grams of simulated regolith and NASA is now considering its feasibility for a future Mars sample return mission.
Conclusion
What began as an adventure into unchartered territory ten years ago has evolved into a robust program that is having significant impact for NASA’s missions as well as missions being pursued by the commercial space industry. Technologies tested with support of the program are slated for missions to the Moon, Mars, and beyond, write John W. Kelly and others from NASA.
“Suborbital flights enable researchers to quickly and iteratively test technologies with the opportunity to make adjustments between flights. The ultimate goal is to change the pace of technology development and drastically shorten the time it takes to bring an idea from the lab to orbit or to the Moon.” — Christopher Baker, Program Executive, Flight Opportunities
References and Resources also include:
https://www.nasa.gov/sites/default/files/atoms/files/jw-kelly-ascend-2020-article.pdf
