CONDENSED STATEMENTS OF CASH FLOWS - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019
Operating activities
Net loss	$ (12,884)	$ (8,276)
Adjustments to reconcile net loss to net cash used in operating activities
Depreciation and amortization expense	248	673
Stock-based compensation	1,452	1,278
Gain on reduction of lease liability	0	1,839
Other	143	151
Change in operating assets and liabilities:
Contracts and other receivables	467	(305)
Prepaid materials	0	368
Prepaid expenses and other assets	748	883
Accounts payable	(297)	(112)
Accrued liabilities	165	(478)
Accrued compensation	(738)	(772)
Contract liabilities	(6)	(2,536)
Other liabilities	(526)	(2,837)
Net cash used in operating activities	(11,228)	(10,124)
Investing activities
Sales of property and equipment	0	282
Acquisition of intangibles	0	(8)
Net cash provided by investing activities	0	274
Financing activities
Proceeds from borrowing under Paycheck Protection Program	662	0
Proceeds from issuance of securities through private placement, net of issuance costs	0	15,505
Proceeds from issuance of common stock, net	1	2,086
Proceeds from exercise of common stock options	0	2
Principal payments on term loan	0	(1,977)
Payments on financing leases	(137)	(130)
Net cash (used in) provided by financing activities	526	15,486
Net decrease in cash and cash equivalents	(10,702)	5,636
Cash and cash equivalents at beginning of period	34,121	13,935
Cash and cash equivalents at end of period	23,419	19,571
Supplemental disclosure of cash flow information
Interest paid	(728)	(854)
Income taxes refunded (paid)	8	(1)
Supplemental disclosure of non-cash investing and financing activities
Non-cash acquisition of property and equipment	$ 0	$ 6