Is the amazing 20th century NASA innovation, Landsat, which has now monitored the Earth’s land areas for over 30 years, about to end? As the former team leader for the Landsat Science Team, I once again am seriously concerned about the future of Landsat in the United States.
Just last August, a major breakthrough in the Landsat saga occurred when the White House declared Landsat operational. The steps outlined in a memo from John H. Marburger , director of the White House Office of Science and Technology Policy, included the transition to the National Polar Orbiting Environmental Satellite System (NPOESS), the initial deployment of NPOESS C-1 in December 2009 and the possible development of a so-called bridge mission to fill the time between now and the C-1 launch. Since that time we have not heard anything but rumors, including:
The bridge mission has been removed from consideration.
C-1 will be delayed until 2010 and probably 2011.
The AM NPOESS will not be launched first in 2009 as planned, but could be delayed to as late as 2015.
Other agencies involved with NPOESS have caused the operational status of Landsat (OLI) to be downgraded to a flight of opportunity so that OLI operations do not interfere with other critical operational responsibilities.
The NPOESS platform is not particularly well suited to Landsat-type observations because of such problems as platform flexing, multiple vibration sources and more.
In general, t he land science community responded to the original Marburger memo with considerable enthusiasm believing t he U.S. government was finally recognizing the operational need for Landsat-type data. However, as time passed, with no open dialogue on the plan, the community has become increasingly concerned that we have returned to business-as-usual, with the data users held at arms length, while critical decisions are made without the benefit of user community input.
Of most immediate concern for the user community, is the apparent dismissal of a bridge mission. Landsat 7 is currently disabled and unlikely to remain functional past early 2008. Landsat 5, having worked for over 20 years, is close to its end. Why a bridge mission could not be procured on an emergency basis and be in orbit in less that four years is hard to understand.
Even if the bridge mission is not deployed until spring 2008, that would cover up to seven years of potentially missed observations depending on when NPOESS C-1 is launched. For many of the evolving applications of Landsat data, such a disruption in the chronological sequence would be severe. It would mean losing track of evolving land cover conditions.
In fact, if C-1 was launched earlier, it would give the community at least a few years of ~8-day repeat coverage between the bridge and NPOESS. Perhaps this could even be used as an opportunity to evaluate how increased temporal repeat coverage could be continued into the future at relatively moderate costs.
The rest of the world is becoming increasingly interested in microsatellite technologies. The recently deployed Disaster Monitoring System developed by Surrey Satellites, the German Rapid Eye systems, under development by MacDonald Dettwiler and activities of SpaceDev are examples. Perhaps the bridge mission provides an opportunity not only to fill a potentially major data gap but also gives us the opportunity to explore new microsatellite technologies for land observations at the same time.
Actions Needed Now
There are some clear and obvious steps that need to be taken today to get the Landsat mission back on track.
Re-engage the user community in discussions on the requirements for an operational Landsat mission;
Develop an advisory process for the NPOESS deployment of the OLI (a.k.a., Landsat) Observatory;
Define and procure a quick, bridge solution to cover the time period between 2008 and 2015; and,
Ensure that Landsat is given proper visibility in the GEO/GEOSS and related NRC activities currently underway.
Samuel N. Goward is a professor in the Department of Geography at the University of Maryland, College Park, Md.