The Canadian Space Agency (CSA) hosted a briefing with reporters yesterday going over the NASA-led OSIRIS-REx mission which is retuning samples on September 24. Canada will receive a sample where it will be housed in a curation facility which will be the first of its kind in the country
The panelists included:
- John Moores, Science Advisor to the President (CSA)
- Timothy Haltigin, Planetary Senior Mission Scientist (CSA)
- Caroline-Emmanuelle Morisset, Program Scientist, Space Exploration Development (CSA)
- Mike Daly, OLA lead instrument scientist (York University)
- Cameron Dickinson, Staff Engineer (MDA)
The following is a summary of the discussion and other mission details.
OSIRIS-REx, which stands for Origins, Spectral Interpretation, Resource Identification, Security-Regolith Explorer, has been in space since 2016 and successfully touched down on asteroid Bennu on Oct. 20, 2020, collecting dust from the surface using a robotic arm during the touch-and-go maneuver. The overall goals of the mission, according to CSA, are:
- Map asteroid Bennu
- Document the sample site
- Measure the asteroid’s orbit, and factors which influence it
- Compare observations at the asteroid to those made from Earth
- Return a sample of Bennu’s surface to Earth for analysis
Scientists study asteroids to learn more about the early solar system, and Bennu is precious in that respect as it has a rare carbon-rich composition.ย Bennu is a near-Earth asteroid, making it relatively easy to access from our planet, and has an elliptical, 436-day orbit that crosses over Earth’s orbit every six years. The spacecraft also required an asteroid at least 200 m (656 feet) in diameter for safe landing operations, making Bennu plenty large as its diameter is 0.5 km (0.3 miles).
On Sept. 24, the expected landing day, OSIRIS-REx will release its landing capsule at roughly a third of the distance to the moon at 63,000 miles (or 102,000 kilometers) above Earth’s surface. The main spacecraft will then redirect itself towards an asteroid called Apophis, which approaches Earth closely on occasion, for a new mission known as OSIRIS-APEX (OSIRIS-Apophis Explorer).
The drop-off capsule is bearing an estimated 250 grams or 8.8 ounces of material from Bennu. It will fly independently in space for four hours, before reaching the Earth’s atmosphere at 10:42 a.m. EDT. It will fly through the atmosphere and then come down to Earth under parachutes. First will be a drogue parachute (two minutes after the spacecraft enters the atmosphere), then the main chute (six minutes after the spacecraft enters the atmosphere).
While the capsule is still in mid-air, a recovery team will use four helicopters to go to its expected landing zone in the desert: a zone at Utah Test and Training Range, southwest of Salt Lake City. The landing zone is a roughly 58 by 14 km (36 by 8.5 mile) area on a military range and its estimated touchdown speed, 13 minutes after launch, will be roughly 18 km/h (11 mph). Engineers will be able to track the capsule’s progress through the atmosphere using thermal instruments, and then optical instruments.
The recovery team plans to arrive on site as quickly as possible to retrieve the capsule from the ground, before Earth’s microbes can contaminate it. They will prepare the capsule for travel to a temporary clean room, where it will be processed, disassembled, and sent on by aircraft to NASA’s Johnson Space Center in Houston. Canada’s sample will be available in a few more months after that.
From Johnson, the sample will be brought to Canada’s own curation facility which will be the first of its kind in the country. The facility will allow for the study of the sample using nitrogen atmosphere, which is less corrosive than the typical oxygen and nitrogen mix found in the births atmosphere. The CSA has established cleaning procedures for all of the tools that will be used to analyze the sample, and monitoring protocols will also be put in place to ensure a lack of contamination and excellent archival knowledge procedures. Loans will be made to the scientific community, with a portion of the sample as well.
Canada will receive four percent of the sample from its $61 million contribution of the OSIRIS-REx Laser Altimeter (OLA) instrument. The instrument has two parts: an electronics box, and a sensor head with two lasers. The lasers include a high-energy laser transmitter (HELT) and a low-energy laser transmitter (LELT).
OLA’s goals, according to CSA, were:
- Scan and measure the surface of the asteroid
- Create a highly accurate 3D model
- Provide scientists with detailed information about Bennu’s shape, distribution of boulders, craters, slopes, and other surface features
- Help researchers and mission planners select the best location from which to gather a sample of the asteroid
The lasers were designed to send short pulses towards the asteroid, and then to recapture the beam bounced off the surface using a receiver. HELT focused on higher altitudes (1 to 7.5 km, or 0.6 miles to 4.7 miles) and LELT on lower altitudes (0.22 km to 1 km, or 0.1 miles to 0.6 miles).
At the time OLA’s contribution was announced in 2014, Canadian government officials stated the lasers would boost lidar know-how, specifically “Canada’s leadership in the niche technologies” associated with lidar. They also said Canada would benefit from “developing cutting-edge Canadian industrial capabilities in optics, and maintaining the global competitiveness of our domestic space industry.”
Both of the laser transmitters operated beyond their expected lifetime. LELT failed before the landing, but collected all of the data that was required for the spacecraft to safely touch down. HELT successfully acquired ranging data throughout the entire mission.
MDA built OLA with large contributions from a subcontractor, Optech, using $8.84 million of Canadian government funding. The technology was based on other flown missions, including a lidar on the CSA’s weather station on the NASA Phoenix Mars lander, and an instrument that flew on the 2005 U.S. Air Force eXperimental Satellite System-11. The lead instrument scientist was Daly, who is both an expert on lidar and who was part of the Canadian Phoenix lander team.
Aside from the instrument itself, Canada provided scientists and engineers on OLA’s development and operations team, as well as scientists from Canadian institutions who were part of the broader OSIRIS-REx science team.